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Silva Fennica 1926-1997
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Acta Forestalia Fennica
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Articles containing the keyword 'boreal'.

Category: Commentary

article id 547, category Commentary
Timo Kuuluvainen. (2002). Introduction. Disturbance dynamics in boreal forests: defining the ecological basis of restoration and management of biodiversity. Silva Fennica vol. 36 no. 1 article id 547. https://doi.org/10.14214/sf.547
  • Kuuluvainen, Department of Forest Ecology, P.O. Box 27, FIN-00014 University of Helsinki, Finland ORCID ID:E-mail: timo.kuuluvainen@helsinki.fi (email)

Category: Research article

article id 10016, category Research article
Ivars Kļaviņš, Arta Bārdule, Zane Lībiete, Dagnija Lazdiņa, Andis Lazdiņš. (2019). Impact of biomass harvesting on nitrogen concentration in the soil solution in hemiboreal woody ecosystems. Silva Fennica vol. 53 no. 4 article id 10016. https://doi.org/10.14214/sf.10016
Highlights: Soil solution nitrogen concentrations in whole-tree harvesting sites are higher in sites of medium to high fertility than in sites of low fertility; In whole-tree harvesting and stem-only harvesting sites, soil solution nitrogen concentrations are highest 2 to 3 years after harvesting; The risks of nitrogen leaching immediately after harvesting are higher in traditional forestry systems compared to short-rotation cropping.

Considering the increasing use of wood biomass for energy and the related intensification of forest management, the impacts of different intensities of biomass harvesting on nutrient leaching risks must be better understood. Different nitrogen forms in the soil solution were monitored for 3 to 6 years after harvesting in hemiboreal forests in Latvia to evaluate the impacts of different biomass harvesting regimes on local nitrogen leaching risks, which potentially increase eutrophication in surface waters. In forestland dominated by Scots pine Pinus sylvestris L. or Norway spruce Picea abies L. (Karst.), the soil solution was sampled in: (i) stem-only harvesting (SOH), (ii) whole‐tree harvesting, with only slash removed (WTH), and (iii) whole‐tree harvesting, with both slash and stumps harvested (WTH + SB), subplots. In agricultural land, sampling was performed in an initially fertilised hybrid aspen (Populus tremula L.× P. tremuloides Michx.) short-rotation coppice (SRC), where above-ground biomass was harvested. In forestland, soil solution N (nitrogen) concentrations were highest in the second and third year after harvesting. Mean annual values in WTH subplots of medium to high fertility sites exceeded the mean values in SOH subplots and control subplots (mature stand where no harvesting was performed) for the entire study period; the opposite trend was observed for the low-fertility site. Biomass harvesting in the hybrid aspen SRC only slightly affected NO3-N (nitrate nitrogen) and NH4+-N (ammonium nitrogen) concentrations in the soil solution within 3 years after harvesting, but a significant decrease in the TN (total nitrogen) concentration in the soil solution was found in plots with additional N fertilisation performed once initially.

  • Kļaviņš, Latvian State Forest Research Institute “Silava”, 111 Rigas Str., LV 2169, Salaspils, Latvia; University of Latvia, Raiņa blvd 19-125, LV 1586, Riga, Latvia ORCID ID:E-mail: ivars.klavins@silava.lv (email)
  • Bārdule, Latvian State Forest Research Institute “Silava”, 111 Rigas Str., LV 2169, Salaspils, Latvia; University of Latvia, Raiņa blvd 19-125, LV 1586, Riga, Latvia ORCID ID:E-mail: arta.bardule@silava.lv
  • Lībiete, Latvian State Forest Research Institute “Silava”, 111 Rigas Str., LV 2169, Salaspils, Latvia ORCID ID:E-mail: zane.libiete@silava.lv
  • Lazdiņa, Latvian State Forest Research Institute “Silava”, 111 Rigas Str., LV 2169, Salaspils, Latvia ORCID ID:E-mail: dagnija.lazdina@silava.lv
  • Lazdiņš, Latvian State Forest Research Institute “Silava”, 111 Rigas Str., LV 2169, Salaspils, Latvia ORCID ID:E-mail: andis.lazdins@silava.lv
article id 10150, category Research article
Petri Forsström, Jouni Peltoniemi, Miina Rautiainen. (2019). Seasonal dynamics of lingonberry and blueberry spectra. Silva Fennica vol. 53 no. 2 article id 10150. https://doi.org/10.14214/sf.10150
Highlights: Seasonal series of multiangular spectra for lingonberry (Vaccinium vitis-idaea L.) and blueberry (Vaccinium myrtillus L.); Decidous blueberry has strong seasonal pattern while temporal variations of evergreen lingonberry were linked to phenological stages of flowering and berrying; Detection of flowers and berries from shrub spectra was possible; Collected spectral data are openly available through SPECCHIO Spectral Information System.

Accurate mapping of the spatial distribution of understory species from spectral images requires ground reference data which represent the prevailing phenological stage at the time of image acquisition. We measured the spectral bidirectional reflectance factors (BRFs, 350–2500 nm) at varying view angles for lingonberry (Vaccinium vitis-idaea L.) and blueberry (Vaccinium myrtillus L.) throughout the growing season of 2017 using Finnish Geospatial Research Institute’s FIGIFIGO field goniometer. Additionally, we measured spectra of leaves and berries of both species, and flowers of lingonberry. Both lingonberry and blueberry showed seasonality in visible and near-infrared spectral regions which was linked to occurrences of leaf growth, flowering, berrying, and leaf senescence. The seasonality of spectra differed between species due to different phenologies (evergreen vs. deciduous). Vegetation indices, normalized difference vegetation index (NDVI), moisture stress index (MSI), plant senescence reflectance index (PSRI), and red-edge inflection point (REIP2), showed characteristic seasonal trends. NDVI and PSRI were sensitive to the presence of flowers and berries of lingonberry, while with blueberry the effects were less evident. Off-nadir observations supported differentiating the dwarf shrub species from each other but showed little improvement for detection of flowers and berries. Lingonberry and blueberry can be identified by their spectral signatures if ground reference data are available over the entire growing season. The spectral data measured in this study are reposited in the publicly open SPECCHIO Spectral Information System.

  • Forsström, Aalto University, School of Engineering, Department of Built Environment, FI-00076 Aalto, Finland ORCID ID: https://orcid.org/0000-0002-2357-2517 E-mail: petri.forsstrom@aalto.fi (email)
  • Peltoniemi, Finnish Geospatial Research Institute (FGI), Department of Geodesy and Geodynamics, Geodeetinrinne 2, FI-02430 Masala, Finland ORCID ID: https://orcid.org/0000-0002-4701-128X E-mail: jouni.peltoniemi@nls.fi
  • Rautiainen, Aalto University, School of Engineering, Department of Built Environment, FI-00076 Aalto, Finland; Aalto University, Department of Electronics and Nanoengineering, FI-00076 Aalto, Finland ORCID ID: https://orcid.org/0000-0002-6568-3258 E-mail: miina.a.rautiainen@aalto.fi
article id 1665, category Research article
Lauri Haataja, Ville Kankaanhuhta, Timo Saksa. (2018). Reliability of self-control method in the management of non-industrial private forests. Silva Fennica vol. 52 no. 1 article id 1665. https://doi.org/10.14214/sf.1665
Highlights: Self-control method was found reliable at the main stages of the forest regeneration process; Only slight overestimation was found in self-control results of soil preparation and planting and small underestimation in self-control of young stand management; Diverse utilizing of self-control data is possible in support of service providers operations.
This study seeks to determine the extent to which self-control data can be relied upon in the management of private forests. Self-control (SC) requires the forest workers to evaluate their own work quality to ensure the clients’ needs are met in terms of soil preparation, planting and young stand management. Self-control data were compared to an independent evaluation of the same worksites. Each dataset had a hierarchical structure (e.g., sample plot, regeneration area and contractor), and key quality indicators (i.e., number of prepared mounds, planted seedlings or crop trees) were measured for each plot.  Self-control and independent-assessments (IA) were analyzed by fitting a multi-level multivariate model containing explanatory variables. No significant differences were observed in terms of soil preparation (number of mounds) or young stand management (number of crop trees) between self-control and independent-assessments. However, the self-control planting data included a slight but significant overestimation of the number of planted seedlings. Discrepancies are discussed in terms of sampling error and other explanatory factors. According to overall results, self-control methods are reliable at every stage of the forest regeneration process. As such, the diverse utilizing of self-control data is possible in support of service providers operations.
  • Haataja, Natural Resources Institute Finland (Luke), Natural resources, Juntintie 154, FI-77600 Suonenjoki, Finland ORCID ID:E-mail: lauritapiohaataja@gmail.com (email)
  • Kankaanhuhta, Natural Resources Institute Finland (Luke), Natural resources, Juntintie 154, FI-77600 Suonenjoki, Finland ORCID ID:E-mail: ville.kankaanhuhta@luke.fi
  • Saksa, Natural Resources Institute Finland (Luke), Natural resources, Juntintie 154, FI-77600 Suonenjoki, Finland ORCID ID:E-mail: timo.saksa@luke.fi
article id 7746, category Research article
Jānis Donis, Māra Kitenberga, Guntars Šņepsts, Roberts Matisons, Juris Zariņš, Āris Jansons. (2017). The forest fire regime in Latvia during 1922–2014. Silva Fennica vol. 51 no. 5 article id 7746. https://doi.org/10.14214/sf.7746
Highlights: Climate effects and human influence on forest fire activity in Latvia was assessed using time-series analysis; Drought conditions during summer season had the strongest effect on fire activity of tested climatic variables; Negative trends and spatial distribution pattern of fire activity suggests of prevailing human influence on forest fire regime over the 20th century.

Fire as disturbance of forests has an important ecological and economical role in boreal and hemiboreal forests. The occurrence of forest fires is both climatically and anthropogenically determined and shifts in fire regimes are expected due to climate change. Although fire histories have been well documented in boreal regions, there is still insufficient information about fire occurrence in the Baltic States. In this study, spatio-temporal patterns and climatic drivers of forest fires were assessed by means of spatial and time-series analysis. The efficiency of Canadian Fire Weather (FWI) indices as indicators for fire activity was tested. The study was based on data from the literature, archives, and the Latvian State Forest service database. During the period 1922–2014, the occurrence and area affected by forest fires has decreased although the total area of forest land has nearly doubled, suggesting improvement of the fire suppression system as well as changes in socioeconomic situation. The geographical distribution of forest fires revealed two pronounced clusters near the largest cities of Riga and Daugavpils, suggesting dominance of human causes of ignitions. The occurrence of fires was mainly influenced by drought. FWI appeared to be efficient in predicting the fire occurrence: 23–34% of fires occurred on days with a high or extremely high fire danger class, which overall had a relative occurrence of only 4.3–4.6%. During the 20th century, the peak of fire activity shifted from May to April, probably due to global warming and socioeconomic reasons. The results of this study are relevant for forest hazard mitigation and development of fire activity prediction system in Latvia.

  • Donis, LSFRI “Silava”, Rigas str. 111, Salaspils, Latvia, LV2169 ORCID ID:E-mail: janis.donis@silava.lv
  • Kitenberga, LSFRI “Silava”, Rigas str. 111, Salaspils, Latvia, LV2169 ORCID ID:E-mail: mara.kitenberga@gmail.com (email)
  • Šņepsts, LSFRI “Silava”, Rigas str. 111, Salaspils, Latvia, LV2169 ORCID ID:E-mail: guntars.snepsts@silava.lv
  • Matisons, LSFRI “Silava”, Rigas str. 111, Salaspils, Latvia, LV2169 ORCID ID:E-mail: robism@inbox.lv
  • Zariņš, LSFRI “Silava”, Rigas str. 111, Salaspils, Latvia, LV2169 ORCID ID:E-mail: juris.zarins@silava.lv
  • Jansons, LSFRI “Silava”, Rigas str. 111, Salaspils, Latvia, LV2169 ORCID ID:E-mail: aris.jansons@silava.lv
article id 1323, category Research article
Tiina Laine, Kalle Kärhä, Antti Hynönen. (2016). A survey of the Finnish mechanized tree-planting industry in 2013 and its success factors. Silva Fennica vol. 50 no. 2 article id 1323. https://doi.org/10.14214/sf.1323
Highlights: In 2013, 31 planting machines were operated by 22 businesses and planted 4.7 million seedlings on 2663 hectares in Finland; Critical success factors included expertise of planting machine operators, high quality planting, adequate amount of work, stoniness, and removal of slash; Growth of the industry will depend on improved cost-efficiency, appropriate worksites, marketing, development of planting machines.

The aim of the study was to update the information pertaining to mechanized tree-planting activity in Finland in 2013 and its success factors. All businesses providing a mechanized tree-planting service were interviewed and asked to describe their equipment and activities, identify critical success factors (CSFs), and suggest areas for improvement. In 2013, 31 planting machines (18 Bracke P11.a, 11 M-Planter and 2 Risutec) operated by 22 businesses planted approximately 4.7 million seedlings on 2663 hectares. CSFs included expertise of planting machine operators, high quality planting, adequate amount of work, stoniness, and removal of slash. Based on the survey, some recommendations for improving mechanized planting work can be made. Firstly, improving the cost-efficiency of mechanized planting is necessary to enhance businesses’ profitability. Secondly, worksite selection is crucial as stoniness, stumps and slash debris diminish productivity. Lastly, the popularity of mechanized planting in the future will benefit from more marketing. Many businesses were unwilling to increase the area of service, invest in new equipment, or increase the volume of planting work but they believed that mechanized planting will become more popular in the near future.

  • Laine, Natural Resources Institute Finland (Luke), Management and Production of Renewable Resources, Juntintie 154, FI-77600 Suonenjoki, Finland ORCID ID:E-mail: tiina.laine@luke.fi (email)
  • Kärhä, Stora Enso Wood Supply Finland, P.O. Box 309, FI-00101 Helsinki, Finland ORCID ID:E-mail: kalle.karha@storaenso.com
  • Hynönen, University of Eastern Finland, Faculty of Science and Forestry, P.O. Box 111, FI-80101 Joensuu, Finland ORCID ID:E-mail: hynonena@gmail.com
article id 1403, category Research article
Kristina Mjöfors, Monika Strömgren, Hans-Örjan Nohrstedt, Annemieke Ingrid Gärdenäs. (2015). Impact of site-preparation on soil-surface CO2 fluxes and litter decomposition in a clear-cut in Sweden. Silva Fennica vol. 49 no. 5 article id 1403. https://doi.org/10.14214/sf.1403
Highlights: Disturbances of the soil did not lead to higher CO2 emissions from the soil; Heavy mixing of the soil lead to lower CO2 emissions from the soil; Buried needles and coarse roots decomposed faster than those on the surface; Abundance of δ15N decreased in needles and roots after site preparation.

Boreal forest soil contains significant amounts of organic carbon. Soil disturbance, caused for example by site preparation or stump extraction, may increase decomposition and thus lead to higher CO2 emissions, contributing to global warming. The aim of this study was to quantify responses of soil-surface CO2 fluxes (Rs) and litter (needle and root) decomposition rates following various kinds of soil disturbance commonly caused by mechanical site preparation and stump harvest. For this purpose four treatments were applied in a clear-cut site in central Sweden: i) removal of the humus layer and top 2 cm of mineral soil, ii) placement of a humus layer and 2 cm of mineral soil upside down on top of undisturbed soil, forming a double humus layer buried under mineral soil, iii) heavy mixing of the humus layer and mineral soil, and iv) no disturbance (control). Rs measurements were acquired with a portable respiration system during two growing seasons. To assess the treatments’ effects on litter decomposition rates, needles or coarse roots (Ø = 6 mm) were incubated in litterbags at positions they would be located after the treatments (buried, or on top of the soil). The results indicate that site preparation-simulating treatments have no effect or may significantly reduce, rather than increase, CO2 emissions during the following two years. They also show that buried litter decomposes more rapidly than litter on the surface, but in other respects the treatments have little effect on litter decomposition rates.

  • Mjöfors, Swedish University of Agricultural Sciences (SLU), Department of Soil and Environment, P.O. Box 7014, 150 07 Uppsala, Sweden ORCID ID:E-mail: kristina.mjofors@slu.se (email)
  • Strömgren, Swedish University of Agricultural Sciences (SLU), Department of Soil and Environment, P.O. Box 7014, 150 07 Uppsala, Sweden ORCID ID:E-mail: Monika.stromgren@slu.se
  • Nohrstedt, Swedish University of Agricultural Sciences (SLU), Department of Soil and Environment, P.O. Box 7014, 150 07 Uppsala, Sweden ORCID ID:E-mail: Hans-orjan.nohrstedt@slu.se
  • Gärdenäs, Swedish University of Agricultural Sciences (SLU), Department of Soil and Environment, P.O. Box 7014, 150 07 Uppsala, Sweden ORCID ID:E-mail: Annemieke.gardenas@slu.se
article id 1279, category Research article
Andreas Kreutz, Tuomas Aakala, Russell Grenfell, Timo Kuuluvainen. (2015). Spatial tree community structure in three stands across a forest succession gradient in northern boreal Fennoscandia. Silva Fennica vol. 49 no. 2 article id 1279. https://doi.org/10.14214/sf.1279
Highlights: We studied the tree community spatial structure in three 1.2-ha plots representing naturally developed northern boreal forests of varying ages; Spatial structure showed little differences between the mid-successional, late-successional and old-growth stands; The occurrence of Picea abies relative to Betula spp. indicated a mosaic-like spatial assembly; Mosaics are likely maintained by species-specific replacement, not reciprocal replacement as thought earlier.
Development of species composition during succession is well studied in natural boreal forests, but empirical assessments of how within-stand spatial structure develops in late-successional stages are few. Here, we quantified spatial patterns in three unmanaged stands consisting of Picea abies (L.) Karst. and Betula pubescens Ehrh. and Betula pendula Roth (hereafter Betula spp.) in northern boreal Fennoscandia. We conducted a comprehensive analysis of small-scale spatial point patterns in three fully mapped 1.2-ha sample plots, representing different forest developmental stages: mid-successional, late-successional and old-growth forest. We used several variants of Ripley’s K-function to analyze the spatial point patterns along the successional gradient. Univariate analyses showed that mature trees of both species were either randomly distributed or clumped. P. abies saplings were clumped, and Betula spp. saplings occurred in a random or clumped manner. In the bivariate analyses, saplings were more likely to be found in the surroundings of mature trees of the same species, but occurred independent of the individuals of other tree species. Mature trees showed interspecific repulsion. Only modest differences occurred in the univariate patterns between the three successional stages, but in the bivariate analyses the most evident patterns, i.e. intraspecific attraction and interspecific repulsion, were stronger in the older successional stages. Overall, the studied stands appear structured as species-specific mosaics. These mosaics, along with mixed species composition, seem to be maintained by species self-replacement, which contrasts with findings from earlier studies.
  • Kreutz, Department of Forest Sciences, University of Helsinki, P.O. Box 27, FI-00014 University of Helsinki, Finland ORCID ID:E-mail: andreas.kreutz@wald-rpl.de
  • Aakala, Department of Forest Sciences, University of Helsinki, P.O. Box 27, FI-00014 University of Helsinki, Finland ORCID ID: http://orcid.org/0000-0003-0160-6410 E-mail: tuomas.aakala@helsinki.fi (email)
  • Grenfell, Department of Forest Sciences, University of Helsinki, P.O. Box 27, FI-00014 University of Helsinki, Finland ORCID ID:E-mail: russell.grenfell@gmail.com
  • Kuuluvainen, Department of Forest Sciences, University of Helsinki, P.O. Box 27, FI-00014 University of Helsinki, Finland ORCID ID:E-mail: timo.kuuluvainen@helsinki.fi
article id 1190, category Research article
Jaakko Repola, Kristina Ahnlund Ulvcrona. (2014). Modelling biomass of young and dense Scots pine (Pinus sylvestris L.) dominated mixed forests in northern Sweden. Silva Fennica vol. 48 no. 5 article id 1190. https://doi.org/10.14214/sf.1190
Highlights: The biomass allocation to tree components is different in unmanaged and managed young stands; Higher foliage biomass and lower stem and branch biomass were detected in the unmanaged stands; Models for trees from young and dense stands provide better estimates of biomass in such stands than those based on data from managed stands.
Biomass models for the biomass of above-ground tree components of Scots pine (Pinus sylvestris L.), Norway spruce (Picea abies [L.] Karst.) and birch (Betula pendula Roth and Betula pubescens Ehrh.) in young dense Scots pine dominated forest stands in northern Sweden were constructed. Destructive above-ground biomass sampling was conducted in naturally generated young, dense, Scots pine dominated mixed stands. Three sampling campaigns were undertaken, the first in 1997 and 1998. The second was six years later (2003), and the last 13 years after the first (2010). In total, 280 trees (126 Scots pine, 68 Norway spruce and 86 birches) were sampled from six different stands in northern Sweden. The sampled trees’ diameter at breast height (dbh) was in the range 1–22 cm (Scots pine), 1–21 cm (Norway spruce) and 1–11 cm (birch). Biomass predictions were tested using our models and the widely used biomass models originally constructed for managed stands. The results showed that the biomass allocation to tree components is different in unmanaged and managed young stands; higher foliage biomass and lower stem and branch biomass were detected in the unmanaged stands. The overall conclusion is that the biomass models for managed stands did not produce satisfactory biomass estimates in unthinned, dense, young stands.
  • Repola, Finnish Forest Research Institute, Rovaniemi Research Unit, P.O. Box 16, FI-96301 Rovaniemi, Finland ORCID ID:E-mail: jaakko.repola@metla.fi (email)
  • Ahnlund Ulvcrona, SLU, Forest Biomaterials and Technology, Skogsmarksgränd, SE-901 83 Umeå, Sweden ORCID ID:E-mail: kristina.ulvcrona@slu.se
article id 1207, category Research article
Olli-Pekka Tikkanen, Irina A. Chernyakova. (2014). Past human population history affects current forest landscape structure of Vodlozero National Park, Northwest Russia. Silva Fennica vol. 48 no. 4 article id 1207. https://doi.org/10.14214/sf.1207
Highlights: In large scale (0–20 km), the proportion of spruce in forest stands was positively affected by distance from old villages. This relationship was non-linear with a threshold distance of 15 km; In small scale (0–5 km), old villages affected tree species composition and age structure of forests. Effect on age structure was the strongest on stands growing on mineral soils.
The information about location and size of past human settlements can give new insights into the analysis of landscape structures. Vodlozero National Park (NP) is one the largest strictly protected areas in Northwestern Europe. We mapped the location of historic villages, which were abandoned in 1958, and studied the effect of past human activity in the forest landscape in two different scales using forest survey data. We assessed the possible change in age, volume and tree species composition from the edge of open fields up to the distance of 5 km from villages. We made a larger landscape analysis using a grid of forest stands covering the whole northern part of the NP. The past human activity was clearly visible in the present forest landscape. Distance from villages affected age, volume and tree species composition of the forest stands. This effect was the strongest within the first two kilometers from the villages. At the level of whole northern NP, the proportion of spruce markedly increased after approximately 15 km from the nearest old village. The changes in the forests surrounding the villages were most likely the result of the intensive use of wood for different commodities needed in households and farming, in addition to short rotation slash and burn agriculture. If the occurrence of forest fires was more frequent closer to villages than in more remote areas, it can well explain the observed pattern in the abundance of spruce in the larger landscape that is less tolerant to fire than pine.
  • Tikkanen, Department of Biology, University of Eastern Finland, P.O. Box 111, FI-80101 Joensuu, Finland (Current: School of Forest Sciences, University of Eastern Finland, P.O. Box 111, FI-80101 Joensuu, Finland) & Interdisciplinary Research and Educational Center of Cross-border Communication CARELICA, Institute of History, Political and Social Sciences, Petrozavodsk State University, 33 Lenin Prospectus, 185910 Petrozavodsk, Republic of Karelia, Russia ORCID ID:E-mail: Olli-Pekka.Tikkanen@uef.fi (email)
  • Chernyakova, Interdisciplinary Research and Educational Center of Cross-border Communication CARELICA, Institute of History, Political and Social Sciences, Petrozavodsk State University, 33 Lenin Prospectus, 185910 Petrozavodsk, Republic of Karelia, Russia ORCID ID:E-mail: irina.chernyakova@onego.ru
article id 989, category Research article
Anna Saarsalmi, Pekka Tamminen, Mikko Kukkola. (2014). Effects of long-term fertilisation on soil properties in Scots pine and Norway spruce stands. Silva Fennica vol. 48 no. 1 article id 989. https://doi.org/10.14214/sf.989
Highlights: N fertilisation increased the amount of carbon in the organic layer; N fertilisation decreased the C/N ratio in the surface soil; N addition increased the amount of most nutrients in the organic layer; N fertilisation tended to lower pH, although only slightly.
The response of surface soil after 45- to 52-years to repeated nitrogen and phosphorus fertilisation was studied. This study included 30 factorial experiments established in young (5- to 30-year-old) stands using plots of 900 m2, on average, and by randomising treatments within each experiment. Total amount of N added varied from 534 to 1908 kg ha–1 and that of P from 69 to 193 kg ha–1, repeated at every second N fertilisation. Liming was performed twice; in total, 6000 kg ha–1 of dolomite was applied. Nitrogen fertilisation increased the mass of the organic layer and the amount of carbon and consequently the amounts of most of the elements in the organic layer. In both the organic layer and the 0–10 cm layer of mineral soil, nitrogen fertilisation decreased the C/N ratio and tended to lower pH, although only slightly. Phosphorus fertilisation increased the amounts of P and Ca. Liming increased the total amounts of most elements in the organic layer, except for C and N. We were able to derive models to describe how changes in the chemical properties of the surface soil depended on doses of elements and on site and stand properties.
  • Saarsalmi, Finnish Forest Research Institute, P.O. Box 18, FI-01301 Vantaa, Finland ORCID ID:E-mail: anna.saarsalmi@metla.fi (email)
  • Tamminen, Finnish Forest Research Institute, P.O. Box 18, FI-01301 Vantaa, Finland ORCID ID:E-mail: pekka.tamminen@metla.fi
  • Kukkola, Finnish Forest Research Institute, P.O. Box 18, FI-01301 Vantaa, Finland ORCID ID:E-mail: mikko.kukkola@metla.fi
article id 980, category Research article
Atte Komonen, Panu Halme, Mari Jäntti, Tuuli Koskela, Janne S. Kotiaho, Tero Toivanen. (2014). Created substrates do not fully mimic natural substrates in restoration: the occurrence of polypores on spruce logs. Silva Fennica vol. 48 no. 1 article id 980. https://doi.org/10.14214/sf.980
Highlights: Polypore communities were more homogeneous among created than among natural logs; The old-growth forest indicator Phellinus ferrugineofuscus occurred frequently on natural logs, but occupied only a few created logs; Results show that created logs do not fully mimic natural logs.
Many protected areas have been under intensive forest management prior to protection and thus lack natural ecosystem structures and dynamics. Dead wood is a key structure in forests harboring hundreds of threatened species. We investigated the ecological success of dead wood creation as a boreal forest restoration measure. We analysed whether the polypore communities of chain-saw felled and girdled (subsequently fallen) Norway spruce (Picea abies (L.) H. Karst.) logs differ from naturally formed spruce logs of similar decay stage and size. The study was conducted in Leivonmäki National Park in central Finland 8 years after the restoration measures. The average number of polypore species was highest on the chain-saw felled logs and most of the common polypore species were most frequent on this substrate. However, among the natural logs, number of species increased more steeply with increasing number of logs, suggesting greater variation in community composition on this substrate. The old-growth forest indicator Phellinus ferrugineofuscus occurred frequently on natural logs, occupied a few girdled logs but was absent from chain-saw felled logs. Our results show that from the polypore perspective created logs do not fully mimic natural logs, suggesting that creating substrates for species may pose a challenge for restoration.
  • Komonen, Department of Biological and Environmental Science, P.O. Box 35, FI-40014, University of Jyväskylä, Finland ORCID ID:E-mail: atte.komonen@jyu.fi (email)
  • Halme, Department of Biological and Environmental Science, P.O. Box 35, FI-40014, University of Jyväskylä, Finland ORCID ID:E-mail: panu.halme@jyu.fi
  • Jäntti, Department of Biological and Environmental Science, P.O. Box 35, FI-40014, University of Jyväskylä, Finland ORCID ID:E-mail: mari.j.jantti@student.jyu.fi
  • Koskela, Department of Biological and Environmental Science, P.O. Box 35, FI-40014, University of Jyväskylä, Finland ORCID ID:E-mail: tuuli.e.koskela@student.jyu.fi
  • Kotiaho, Department of Biological and Environmental Science, P.O. Box 35, FI-40014, University of Jyväskylä, Finland ORCID ID:E-mail: janne.kotiaho@jyu.fi
  • Toivanen, Department of Biological and Environmental Science, P.O. Box 35, FI-40014, University of Jyväskylä, Finland; Current: Birdlife Finland, Annankatu 29 A 16, FI-00100 Helsinki, Finland ORCID ID:E-mail: tero.toivanen@birdlife.fi
article id 949, category Research article
Ken Olaf Storaunet, Jørund Rolstad, Erlend Rolstad. (2014). Effects of logging on the threatened epiphytic lichen Usnea longissima: an experimental approach. Silva Fennica vol. 48 no. 1 article id 949. https://doi.org/10.14214/sf.949
Highlights: A re-inventory of the threatened lichen Usnea longissima in ten Norway spruce forest stands where experimental selective loggings had been conducted 5 to 8 years before revealed that the number of lichen thalli had increased with 34%; The number of thalli increased more where the forest was open whether or not the low tree density was caused by the loggings.
Usnea longissima Ach. is a circumboreal epiphytic lichen draping tree canopies in moist coastal and mountainous forests. It is extinct from many European and North-American localities, presumably due to industrial forestry and air pollution, but still has a stronghold in parts of Scandinavia and U.S. and Canadian Pacific Northwest. In 2005/06 we used a comparative and retrospective approach to evaluate how present and historic tree and stand characteristics influenced the occurrence and abundance of the lichen (Storaunet et al. 2008). In 2012, we re-inventoried ten Norway spruce forest stands with 401 U. longissima-bearing trees and recorded changes in the number of U. longissima thalli. Seven of the stands had been experimentally, selectively logged 5–8 years before, where the lichen-bearing trees had been marked in the field and were avoided during the logging operation. Total number of lichen-bearing trees decreased slightly (2.9%), whereas the number of thalli had increased with 34%. Number of thalli increased more where the forest was open (low basal area, m2ha-1) whether or not the low tree density was caused by the logging events. At high tree densities the change in number of thalli was negligible. We suggest that selective logging, securing lichen-bearing trees, may be a viable management option to keep tree density from becoming too dense, thereby enhancing growth and establishment of U. longissima.
  • Storaunet, Norwegian Forest and Landscape Institute, P.O. Box 115, NO-1431 Ås, Norway ORCID ID:E-mail: stk@skogoglandskap.no (email)
  • Rolstad, Norwegian Forest and Landscape Institute, P.O. Box 115, NO-1431 Ås, Norway ORCID ID:E-mail: roj@skogoglandskap.no
  • Rolstad, Skogfaglig Rådgivning, Holmsida 126, NO-1488 Hakadal, Norway ORCID ID:E-mail: roe@skogoglandskap.no
article id 973, category Research article
Sergio Rossi, Hubert Morin, François Gionest, Danielle Laprise. (2013). Spatially explicit structure of natural stands dominated by black spruce. Silva Fennica vol. 47 no. 3 article id 973. https://doi.org/10.14214/sf.973
Black spruce [Picea mariana (Mill.) BSP] regeneration emerges in clusters near the pre-existing boles within a few years after the passage of fire. This paper tested the hypothesis that black spruce forests still maintain the spatial structure deriving from postfire stand initiation. Trees and saplings were monitored during 2000-2007 and the horizontal and vertical structure of the stands were investigated on four permanent plots in the boreal forest of Quebec, Canada. Plots showed 1300-2150 trees ha-1, and were composed of trees with homogeneous sizes and a very small proportion of saplings. These characteristics identify single cohorts generated by complete, or almost-complete, stand replacement by fire. Ripley’s L(r) functions showed that the spatial pattern of trees and saplings ranged from random to aggregated, thus demonstrating that the clustering distribution of the individuals in black spruce forests can be maintained even after 80-120 years from stand initiation. These findings could results from incomplete self-thinning or from an environment with heterogeneous distribution of resources. The practices of ecosystem management recently developed in Eastern Canada should take into account both the horizontal and vertical structure to better modulate the competition among individuals during partial harvesting.
  • Rossi, Département des Sciences Fondamentales, Université du Québec à Chicoutimi, 555 boulevard de l’Université, Chicoutimi (QC), G7H2B1, Canada ORCID ID:E-mail: sergio.rossi@uqac.ca (email)
  • Morin, Département des Sciences Fondamentales, Université du Québec à Chicoutimi, 555 boulevard de l’Université, Chicoutimi (QC), G7H2B1, Canada ORCID ID:E-mail: hubert_morin@uqac.ca
  • Gionest, Département des Sciences Fondamentales, Université du Québec à Chicoutimi, 555 boulevard de l’Université, Chicoutimi (QC), G7H2B1, Canada ORCID ID:E-mail: francois_gionest@uqac.ca
  • Laprise, Département des Sciences Fondamentales, Université du Québec à Chicoutimi, 555 boulevard de l’Université, Chicoutimi (QC), G7H2B1, Canada ORCID ID:E-mail: danielle_laprise@uqac.ca
article id 47, category Research article
Iulian Dragotescu, Daniel D. Kneeshaw. (2012). A comparison of residual forest following fires and harvesting in boreal forests in Quebec, Canada. Silva Fennica vol. 46 no. 3 article id 47. https://doi.org/10.14214/sf.47
Residual forests are a key component of post-burned areas creating structure within burns and providing habitat and seed sources. Yet, despite their importance to biodiversity and ecosystem processes there is little information on how similar or different residuals in burned landscape are to harvested landscapes. Our goal was to examine and compare the density, size, shape, and spatial arrangement of residual forest vegetation after fire and clearcutting. We evaluated residual forest in two locations within the boreal mixedwood region of Quebec, Canada using aerial photo interpretation and ArcGIS 9.1 software. We found residual stands to be larger and more abundant in harvested zones relative to sites affected by fire. Differences with respect to shape and spatial arrangement of residual forest were also observed among disturbance types. Factors such as proximity to watercourses, watercourse shape, and physiography affected residual abundance and spatial distribution. Residual forest in harvested zones tended to be more elongated with greater edge due to rules governing forest operations. Despite greater quantity of residual forest in harvested areas than fires, managers should still be prudent as the surrounding forest matrix is reduced in many managed landscapes.
  • Dragotescu, Université du Québec à Montréal, Centre d’Étude de la Forêt (CEF), Montreal, Quebec, Canada ORCID ID:E-mail: idragot@hotmail.com (email)
  • Kneeshaw, Université du Québec à Montréal, Centre d’Étude de la Forêt (CEF), Montreal, Quebec, Canada ORCID ID:E-mail:
article id 53, category Research article
Saana Kataja-aho, Aino Smolander, Hannu Fritze, Sini Norrgård, Jari Haimi. (2012). Responses of soil carbon and nitrogen transformations to stump removal. Silva Fennica vol. 46 no. 2 article id 53. https://doi.org/10.14214/sf.53
We studied in central Finland whether stump harvesting after clear felling of coniferous forest poses further short-term changes in soil carbon and nitrogen dynamics when compared to the traditional site preparation method, mounding. Exposed mineral soil patches in Norway spruce (Picea abies) dominated clear-cut stands were sampled 1–5 years after the treatments. The extent of the exposed mineral soil surface was significantly larger at the stump removal sites when compared to the mounding sites. No differences were found in soil pH, organic matter content or total concentration of soil C between the treatments or treatment years. Total concentration of soil N was consistently higher and C:N ratio lower in the stump removal plots than in the mounded plots. Further, both net N mineralisation and nitrification were clearly increased in the stump removal plots one year after the treatments. Soil microbial activity (CO2 production) was higher in the stump removal plots but similar difference was not found in sieved soil samples incubated in the laboratory. Fluxes of other important greenhouse gases (CH4 and N2O) did not seem to be affected by stump removal. The differences between the stump removal and mounding procedures were most obviously attributed to more substantial soil disturbance by stump pulling and/or differences in the microbial communities and quality of soil organic matter in the differently treated soil.
  • Kataja-aho, University of Jyväskylä, Dept. of Biological and Environmental Science, Jyväskylä, Finland ORCID ID:E-mail: saana.m.kataja-aho@jyu.fi (email)
  • Smolander, Finnish Forest Research Institute, Vantaa, Finland ORCID ID:E-mail:
  • Fritze, Finnish Forest Research Institute, Vantaa, Finland ORCID ID:E-mail:
  • Norrgård, University of Jyväskylä, Dept. of Biological and Environmental Science, Jyväskylä, Finland ORCID ID:E-mail:
  • Haimi, University of Jyväskylä, Dept. of Biological and Environmental Science, Jyväskylä, Finland ORCID ID:E-mail:
article id 89, category Research article
Russell Grenfell, Tuomas Aakala, Timo Kuuluvainen. (2011). Microsite occupancy and the spatial structure of understorey regeneration in three late-successional Norway spruce forests in northern Europe. Silva Fennica vol. 45 no. 5 article id 89. https://doi.org/10.14214/sf.89
We compared microsite occupancy and three spatial structure of regeneration in three primeval late-successional Norway spruce dominated forests. One area lay in the middle boreal zone in Russia (Dvina-Pinega) where larger-scale disturbance from bark beetles and drought had occurred; the other areas lay in the northern boreal zone, one in Finland (Pallas-Ylläs) had encountered only small-scale disturbance, and one in Russia (Kazkim) had been influenced by fire. We mapped all spruce (Picea abies) and birch (Betula pendula and Betula pubescens) trees with diameter at breast height (DBH) ≥ 10 cm on 40 m 400 m plots, and those with DBH < 10 cm on 2 m or 4 m 400 m subplots. On the subplots we also recorded microsite occupancy and estimated microsite availability. At all study areas small seedlings (h < 0.3 m) of both spruce and birch were found largely on disturbance-related microsites. Birch saplings (h ≥ 1.3 m, DBH < 10 cm) disproportionately occupied deadwood-related microsites at Dvina-Pinega. In contrast, spruce saplings at all study areas, and birch saplings at Kazkim and Pallas-Ylläs, showed less, or no, preference. Our results thus confirm the importance of disturbance-related microsites for regeneration establishment, but not necessarily for long-term survival. No spatial segregation between the overstorey (DBH ≥ 10 cm) and saplings (h ≥ 1.3 m, DBH < 10 cm) or seedlings (h < 1.3 m) was found at Pallas-Ylläs or Kazkim, and only three instances of very weak segregation were found at Dvina-Pinega. This suggests that the regeneration gap concept may not be useful for describing the regeneration dynamics of primeval boreal forests.
  • Grenfell, University of Helsinki, Dept of Forest Sciences, Helsinki, Finland ORCID ID:E-mail: russell.grenfell@helsinki.fi (email)
  • Aakala, University of Helsinki, Dept of Forest Sciences, Helsinki, Finland ORCID ID:E-mail:
  • Kuuluvainen, University of Helsinki, Dept of Forest Sciences, Helsinki, Finland ORCID ID:E-mail:
article id 82, category Research article
Nicole J. Fenton, Yves Bergeron. (2011). Dynamic old-growth forests? A case study of boreal black spruce forest bryophytes. Silva Fennica vol. 45 no. 5 article id 82. https://doi.org/10.14214/sf.82
Old-growth forests have sparked significant interest over the last twenty years and definitions have evolved from structure based to process based, acknowledging the diversity of forests that could be considered old growth. However studies frequently group all forests over a certain age into a single type, negating the dynamic processes that create old growth. In this study we examine a 2350-year chronosequence in boreal black spruce forests in northwestern Quebec to determine whether continued community change can be observed in the bryophyte layer. Bryophytes dominate the understory of boreal forests and influence ecosystem functioning, particularly in paludified forests where production exceeds decomposition in the organic layer. Community composition and richness changed throughout the chronosequence with no evidence of a steady state associated with an old-growth phase. In contrast the bryophyte community continued to evolve with multiple phases being evident. These results suggest that old-growth forests on the Clay Belt of northwestern Quebec and northeastern Ontario, Canada, should be regarded as part of the continuous gradient in forest development rather than a single state. This complicates conservation of these forests as multiple phases should be considered when planning forest reserves.
  • Fenton, Université du Québec en Abitibi-Témiscamingue, 445 Boulevard de l’Université, Rouyn-Noranda, Québec, Canada J9X 4E5 ORCID ID:E-mail: nicole.fenton@uqat.ca (email)
  • Bergeron, Université du Québec en Abitibi-Témiscamingue, 445 Boulevard de l’Université, Rouyn-Noranda, Québec, Canada J9X 4E5 ORCID ID:E-mail:
article id 80, category Research article
Mari T. Jönsson, Shawn Fraver, Bengt Gunnar Jonsson. (2011). Spatio-temporal variation of coarse woody debris input in woodland key habitats in central Sweden. Silva Fennica vol. 45 no. 5 article id 80. https://doi.org/10.14214/sf.80
The persistence of many saproxylic (wood-living) species depends on a readily available supply of coarse woody debris (CWD). Most studies of CWD inputs address stand-level patterns, despite the fact that many saproxylic species depend on landscape-level supplies of CWD. In the present study we used dated CWD inputs (tree mortality events) at each of 14 Norway spruce (Picea abies) dominated woodland key habitat sites to analyze the spatial and temporal patterns of CWD additions between 1950 and 2002 within a small landscape in central Sweden. We found that inputs were episodic within sites, where local windstorms created pulses in CWD input. Pulses occurred simultaneously in many sites, yielding landscape-level synchrony of CWD input. These synchronous pulses, and importantly, the breaks between pulses, may have negative implications for saproxylic species that are dependent on large volume inputs of freshly killed Norway spruce. In addition, the inherent small size and relative isolation of these sites may further increase extinction risks due to stochastic events. However, background CWD input rates occurring between pulses varied substantially among sites, presumably the result of the sites’ varied histories and structural characteristics. This finding suggests that the different sites have varied abilities to provide habitat for saproxylic species during periods with low landscape-level input of CWD.
  • Jönsson, Department of Ecology, SLU, P.O. Box 7044, SE-750 07 Uppsala, Sweden (current); Department of Natural Sciences, Engineering and Mathematics, Mid Sweden University, Sundsvall, Sweden ORCID ID:E-mail: mari.jonsson@slu.se (email)
  • Fraver, U.S. Forest Service, Northern Research Station, Grand Rapids, Minnesota, USA (current); Department of Natural Sciences, Engineering and Mathematics, Mid Sweden University, Sundsvall, Sweden ORCID ID:E-mail:
  • Jonsson, Department of Natural Sciences, Engineering and Mathematics, Mid Sweden University, Sundsvall, Sweden ORCID ID:E-mail:
article id 31, category Research article
Jeovanna Lowe, David Pothier, Jean-Pierre L. Savard, Ghislain Rompré, Mathieu Bouchard. (2011). Snag characteristics and cavity-nesting birds in the unmanaged post-fire northeastern Canadian boreal forest. Silva Fennica vol. 45 no. 1 article id 31. https://doi.org/10.14214/sf.31
We studied the availability and characteristics of snags and their use by cavity-nesting birds in the northeastern part of the Canadian boreal forest. We built up two long-term (> 200 years) chronosequences following time since the last fire in the unmanaged boreal forest of northeastern Québec, one in the balsam fir-white birch domain (southern region) and one in the spruce-mosses domain (northern region). We then sampled and characterized snags and live trees in 30 stands from each of these two chronosequences. We also looked for nest cavities on all sampled snags, performed bird inventories by point counts, and calculated tree mortality rate from permanent sample plots. Results show that mortality rates follow a U-shaped pattern, with more snags of large diameter (> 20 cm DBH) in young (< 50 years) and in old (> 200 years) forests. In the latter, we also found more nest cavities than in any other age classes. Although abundance of primary cavity nesters (excavating species) did not vary among age classes, secondary cavity nesters (using cavities already available) tend to be more numerous in older forests. Our results highlight the capacity for young and old-growth forests to provide quality habitat for species that are dependent on large snags. Proper forest management should maintain a mosaic of different age forest stands, including snags, to promote biodiversity and provide important resources for resident bird species.
  • Lowe, Centre d’étude de la foret, Département des sciences du bois et de la foret, Pavillon Abitibi-Price, 2405 rue de la Terrasse, Université Laval, Québec, Québec, G1V 0A6, Canada ORCID ID:E-mail: jeovannalowe@gmail.com (email)
  • Pothier, Centre d’étude de la foret, Département des sciences du bois et de la foret, Pavillon Abitibi-Price, 2405 rue de la Terrasse, Université Laval, Québec, Québec, G1V 0A6, Canada ORCID ID:E-mail:
  • Savard, Wildlife Research, Science and Technology, Québec Region, 1141 Route de l’Église, P.O. Box 10100, Québec, Québec, G1V 4H5, Canada ORCID ID:E-mail:
  • Rompré, Centre d’étude de la foret, Département des sciences du bois et de la foret, Pavillon Abitibi-Price, 2405 rue de la Terrasse, Université Laval, Québec, Québec, G1V 0A6, Canada & Department of Biology and Health Sciences, 84 West South Street, Wilkes University, PA 18766, USA ORCID ID:E-mail:
  • Bouchard, Ministère des Ressources naturelles et de la Faune, Direction de l’Environnement et de la Protection des Forets, 880 Chemin Ste-Foy, Quebec, Québec, G1S 4X4, Canada ORCID ID:E-mail:
article id 123, category Research article
Staffan Jacobson, Folke Pettersson. (2010). An assessment of different fertilization regimes in three boreal coniferous stands. Silva Fennica vol. 44 no. 5 article id 123. https://doi.org/10.14214/sf.123
In 1981–82 three field experiments were established with the aim of elucidating (i) the growth response of middle-aged coniferous stands at different fertilization intensities and, hence, the economic outcomes; and (ii) the need to add nutrients other than nitrogen (N). Nutrient additions were performed at intervals of two, four, six and eight years. The experiments were established on typical podzolized and N-limited mor-humus sites, two in Scots pine (Pinus sylvestris L.) stands and one in a Norway spruce (Picea abies (L.) Karst.) stand, at three different locations in Sweden. The ages of the stands were 65–70 years at the time of establishment. Growth responses were calculated after a 22-year study period. The growth responses were significant in all treatments. The addition of nutrients other than N did not affect stem growth at any of the sites. The growth response tended to increase with decreasing application interval. The results also revealed that the efficiency of fertilization is reduced as the interval between fertilizations is shortened. Accordingly, the growth effect per kg of added N was negatively correlated to fertilization intensity. The least intensive fertilization regime (an eight-year interval) resulted in an average net increase in C sequestration of 35 kg per kg N added. The profitability, in terms of internal rate of return, the present net value at different interest rates and the cost of production, i.e. the cost to produce one extra m3 under the different N regimes, are presented and discussed.
  • Jacobson, Skogforsk, Uppsala Science Park, SE-75183 Uppsala, Sweden ORCID ID:E-mail: staffan.jacobson@skogforsk.se (email)
  • Pettersson, Skogforsk, Uppsala Science Park, SE-75183 Uppsala, Sweden ORCID ID:E-mail:
article id 128, category Research article
Shelley L. Hunt, Andrew M. Gordon, Dave M. Morris. (2010). Carbon stocks in managed conifer forests in northern Ontario, Canada. Silva Fennica vol. 44 no. 4 article id 128. https://doi.org/10.14214/sf.128
Carbon pools and net primary productivity (aboveground) were measured in managed stands of jack pine (Pinus banksiana Lamb.) and black spruce (Picea mariana [Mill.] B.S.P.), ranging in age from 10 to 53 years, in the Lake Nipigon area of northern Ontario. Organic carbon in the forest floor and surface mineral soil (top 15 cm) ranged from 13 to 46 Mg C ha-1 and 10 to 29 Mg C ha-1, respectively. Carbon in aboveground tree biomass ranged from 11 to 74 Mg C ha-1 in crop trees, and 0 to 11 Mg C ha-1 in non-crop trees. Coarse woody debris (downed woody debris and snags) contained between 1 and 17 Mg C ha-1. Understory vegetation rarely represented more than 1% of total ecosystem carbon accumulation, but was responsible for a larger proportion of aboveground net primary productivity (ANPP). Rates of ANPP (expressed as carbon) ranged from 0.8 to 3.5 Mg C ha-1 y-1. Carbon stocks in managed stands were compared with published values from similarly aged fire-origin stands in the North American boreal region. Carbon stocks in our study stands generally exceeded those in unmanaged fire-origin stands of the same age, due to larger tree and forest floor carbon pools.
  • Hunt, University of Guelph, School of Environmental Sciences, 50 Stone Road East, Guelph, Ontario, Canada N1G 2W1 ORCID ID:E-mail: shunt@uoguelph.ca (email)
  • Gordon, University of Guelph, School of Environmental Sciences, 50 Stone Road East, Guelph, Ontario, Canada N1G 2W1 ORCID ID:E-mail:
  • Morris, Ontario Ministry of Natural Resources, Centre for Northern Forest Ecosystem Research, 955 Oliver Rd., Thunder Bay, Ontario, Canada P7B 5E1 ORCID ID:E-mail:
article id 168, category Research article
Saila Varis, Anne Pakkanen, Aina Galofré, Pertti Pulkkinen. (2009). The extent of south-north pollen transfer in Finnish Scots pine. Silva Fennica vol. 43 no. 5 article id 168. https://doi.org/10.14214/sf.168
In order to evaluate the possibility of long distance gene flow in Scots pine (Pinus sylvestris L.), we measured the amount and germinability of airborne pollen and flowering phenology in central, northern, and northernmost Finland during 1997–2000. Totally 2.3% of the detected germinable pollen grains were in the air prior to local pollen shedding. The mean number of germinable pollen grains m–3 air per day was lower prior to local pollen shedding, but in the year 2000 there were more germinable pollen grains in the air of central study site prior to local pollen shedding. Prior to the onset of pollen shedding, 7.5% of female strobili which we observed were receptive. On average female strobili became receptive three days earlier than local pollen shedding started. During the period of pollen shedding in the central study site, we detected germinable airborne pollen in the northern site in years 1997, 1999 and 2000. At the northermost site, we detected germinable airborne pollen during the pollen-shedding period of the northern site in 2000. Our detection of germinable airborne pollen and synchrony of strobili maturation from south to north suggest that populations of Scots pine in central and northern Finland may provide genetic material to populations in northern and northernmost Finland, respectively.
  • Varis, Finnish Forest Research Institute, Vantaa Research Unit, P.O. Box 18, FI-01301 Vantaa, Finland ORCID ID:E-mail: saila.varis@metla.fi (email)
  • Pakkanen, Finnish Forest Research Institute, Vantaa Research Unit, P.O. Box 18, FI-01301 Vantaa, Finland ORCID ID:E-mail:
  • Galofré, Passeig de l’estació 21, 5-1, 43800 Valls, Tarragona, Spain ORCID ID:E-mail:
  • Pulkkinen, Finnish Forest Research Institute, Haapastensyrjä Breeding Station, Karkkilantie 247, FI-12600 Läyliäinen, Finland ORCID ID:E-mail:
article id 225, category Research article
Johan Bergh, Urban Nilsson, Harald Grip, Per-Ola Hedwall, Tomas Lundmark. (2008). Effects of frequency of fertilisation on production, foliar chemistry and nutrient leaching in young Norway spruce stands in Sweden. Silva Fennica vol. 42 no. 5 article id 225. https://doi.org/10.14214/sf.225
Keywords: sludge; wood-ash; boreal; N; P; K
There is a great need to increase the production in Swedish forests to meet future demand from the forest industry and the bio-energy sector. One option to increase the production is to supply nutrients to young stands of Norway spruce. For the practical application it is important to develop and optimise fertilisation regimes in terms of production, economy and leaching of nutrients. The frequency of fertilisation is one important variable in the fertilisation regime, and this study aimed to study effects of different fertilisation frequencies on production and leaching of nitrogen. In 2001, five field experiments were established in southern, central and northern Sweden. Young stands of Norway spruce were fertilised every year, every second year and every third year. In addition, fertilisation with sludge pellets and wood-ash combined with nitrogen was investigated. The current annual increment after five years of treatment was significantly larger in fertilised than in unfertilised treatments. The difference in production between fertilisation every year and every second year was insignificant, while fertilisation every third year resulted in lower production. Sludge pellets and wood-ash fertilisation gave significantly lower production than fertilisation every second year even though approximately the same amount of nitrogen was applied. There was relatively little leaching of nitrate to ground water in all treatments; 0.6–1 kg N ha–1 a–1 from plots with fertilisation every year or every second year; and 2.7 kg N ha–1 a–1 from plots with fertilisation every third year. Most of the leaching was after the first fertilisation, in all treatments at all sites.
  • Bergh, Swedish University of Agricultural Sciences, Southern Swedish Forest Research Centre, P.O. Box 49, SE-230 53 Alnarp, Sweden ORCID ID:E-mail: johan.bergh@ess.slu.se (email)
  • Nilsson, Swedish University of Agricultural Sciences, Southern Swedish Forest Research Centre, P.O. Box 49, SE-230 53 Alnarp, Sweden ORCID ID:E-mail:
  • Grip, Swedish University of Agricultural Sciences, Southern Swedish Forest Research Centre, P.O. Box 49, SE-230 53 Alnarp, Sweden ORCID ID:E-mail:
  • Hedwall, Swedish University of Agricultural Sciences, Southern Swedish Forest Research Centre, P.O. Box 49, SE-230 53 Alnarp, Sweden ORCID ID:E-mail:
  • Lundmark, Swedish University of Agricultural Sciences, Southern Swedish Forest Research Centre, P.O. Box 49, SE-230 53 Alnarp, Sweden ORCID ID:E-mail:
article id 235, category Research article
Ari Nikula, Ville Hallikainen, Risto Jalkanen, Mikko Hyppönen, Kari Mäkitalo. (2008). Modelling the factors predisposing Scots pine to moose damage in artificially regenerated sapling stands in Finnish Lapland. Silva Fennica vol. 42 no. 4 article id 235. https://doi.org/10.14214/sf.235
Moose (Alces alces) damage in forest plantations have been at a high level in Finland in recent decades. Nowadays, moose is the most severe pest in Scots pine plantations also in Finnish Lapland. So far, despite the high level of damage and different bio-geographical conditions in Northern Finland, most of the moose-damage research has been carried out in Southern Finland. A number of research have also been performed to analyse factors affecting browsing but predictive models are rare. Data from 123 randomly selected and artificially regenerated pine plantations in Northern Finland were used in modelling the risk of moose browsing. The stands had been regenerated during 1984–1995. A total of 508 sample plots (range 2–8 plots per stand) were measured. Hierarchical logistic regression models with a random factor were constructed to predict the probability of leader-shoot browsing of pine on a plot. The number of planted pines and deciduous trees overtopping the pines were the most important predictors increasing the browsing probability. The results support earlier findings that deciduous trees overtopping or reaching the height of the pines should be cleaned from the immediate vicinity of the pines. Seedlings with a height ranging from 75 to 299 centimetres were more susceptible to browsing. Heavy soil scarification, such as ploughing or mounding, increased the browsing probability compared with lighter scarification methods. Soil type did not affect the browsing probability, but paludification decreased it. The within-stand variation in deciduous trees density and height should be taken into account in future moose browsing risk assessments. In Lapland, high moose damage risk areas are characterized by a low elevation and higher temperature sum.
  • Nikula, Finnish Forest Research Institute, Rovaniemi Research Unit, Eteläranta 55, FI-96300 Rovaniemi, Finland ORCID ID:E-mail: ari.nikula@metla.fi (email)
  • Hallikainen, Finnish Forest Research Institute, Rovaniemi Research Unit, Eteläranta 55, FI-96300 Rovaniemi, Finland ORCID ID:E-mail:
  • Jalkanen, Finnish Forest Research Institute, Rovaniemi Research Unit, Eteläranta 55, FI-96300 Rovaniemi, Finland ORCID ID:E-mail:
  • Hyppönen, Finnish Forest Research Institute, Rovaniemi Research Unit, Eteläranta 55, FI-96300 Rovaniemi, Finland ORCID ID:E-mail:
  • Mäkitalo, Finnish Forest Research Institute, Rovaniemi Research Unit, Eteläranta 55, FI-96300 Rovaniemi, Finland ORCID ID:E-mail:
article id 250, category Research article
Saara Lilja-Rothsten, Michelle de Chantal, Chris Peterson, Timo Kuuluvainen, Ilkka Vanha-Majamaa, Pasi Puttonen. (2008). Microsites before and after restoration in managed Picea abies stands in southern Finland: effects of fire and partial cutting with dead wood creation. Silva Fennica vol. 42 no. 2 article id 250. https://doi.org/10.14214/sf.250
Different types of microsites, e.g. CWD (coarse woody debris), mounds, and uprooting pits, are important for tree regeneration and biodiversity. However, microsite diversity is greatly reduced in managed stands. We studied how restoration treatments changed microsite distribution in mature managed Picea abies stands. Four cutting treatments were used: uncut, low-CWD (5 m3 ha–1 of down retention trees, DRT, and 50 m3 ha–1 of standing retention trees), intermediate-CWD (as previous but leaving 30 m3 ha–1 of DRT), and high-CWD (as previous but with 60 m3 ha–1 of DRT). Timber harvested from stands ranged from 108–168 m3 ha–1. Half of the stands were burned, and half remained unburned. Sampling was stratified into upland and paludified biotopes within each stand. The pre-treatment microsite distributions were dominated by level ground in both biotopes; mounds and microsites on or next to CWD or a stump were slightly more abundant in the paludified than in the upland biotopes. Microsites were more diverse after cutting, with and without fire. The cutting treatment increased the relative abundances of microsites on or next to CWD. Fire consumed small diameter dead wood and flattened mounds. Microsites were more diverse in paludified than in upland biotopes. The results demonstrate that microsite diversity can rapidly be restored to structurally impoverished managed Picea stands despite a large portion of wood volume being harvested.
  • Lilja-Rothsten, University of Helsinki, Dept. of Forest Ecology, Finland ORCID ID:E-mail: saara.lilja@helsinki.fi (email)
  • Chantal, University of Helsinki, Dept. of Forest Ecology, Finland ORCID ID:E-mail:
  • Peterson, Dept. of Plant Biology, University of Georgia, Athens, GA, USA ORCID ID:E-mail:
  • Kuuluvainen, University of Helsinki, Dept. of Forest Ecology, Finland ORCID ID:E-mail:
  • Vanha-Majamaa, The Finnish Forest Research Institute, Vantaa Unit, Finland ORCID ID:E-mail:
  • Puttonen, The Finnish Forest Research Institute, Vantaa Unit, Finland ORCID ID:E-mail:
article id 318, category Research article
Sofia Backéus, Peder Wikström, Tomas Lämås. (2006). Modeling carbon sequestration and timber production in a regional case study. Silva Fennica vol. 40 no. 4 article id 318. https://doi.org/10.14214/sf.318
Forests make up large ecosystems and by the uptake of carbon dioxide can play an important role in mitigating the greenhouse effect. In this study, mitigation of carbon emissions through carbon uptake and storage in forest biomass and the use of forest biofuel for fossil fuel substitution were considered. The analysis was performed for a 3.2 million hectare region in northern Sweden. The objective was to maximize net present value for harvested timber, biofuel production and carbon sequestration. A carbon price for build-up of carbon storage and for emissions from harvested forest products was introduced to achieve an economic value for carbon sequestration. Forest development was simulated using an optimizing stand-level planning model, and the solution for the whole region was found using linear programming. A range of carbon prices was used to study the effect on harvest levels and carbon sequestration. At a zero carbon price, the mean annual harvest level was 5.4 million m3, the mean annual carbon sequestration in forest biomass was 1.48 million tonnes and the mean annual replacement of carbon from fossil fuel with forest biofuel was 61 000 tonnes. Increasing the carbon price led to decreasing harvest levels of timber and decreasing harvest levels of forest biofuel. Also, thinning activities decreased more than clear-cut activities when the carbon prices increased. The level of carbon sequestration was governed by the harvest level and the site productivity. This led to varying results for different parts of the region.
  • Backéus, SLU, Dept. of Forest Resource Management and Geomatics, SE-901 83 Umeå, Sweden ORCID ID:E-mail: sofia.backeus@resgeom.slu.se (email)
  • Wikström, SLU, Dept. of Forest Resource Management and Geomatics, SE-901 83 Umeå, Sweden ORCID ID:E-mail:
  • Lämås, SLU, Dept. of Forest Resource Management and Geomatics, SE-901 83 Umeå, Sweden ORCID ID:E-mail:
article id 339, category Research article
John W. McCarthy, Gordon Weetman. (2006). Age and size structure of gap-dynamic, old-growth boreal forest stands in Newfoundland. Silva Fennica vol. 40 no. 2 article id 339. https://doi.org/10.14214/sf.339
The age and size structure of trees in old Abies-Picea-Betula forests on Newfoundland’s Great Northern Peninsula were examined. It was hypothesized that the size and age structure of both the tree and regeneration “strata” of these stands display the complex structural heterogeneity characteristic of classic, self-regenerating, uneven-aged old-growth stands, and that the development and dynamics of such structures occur over long periods of time. With all tree species combined, dbh (diameter at breast height) and height distributions exhibited a strong reverse-J character, with well-defined, semi-logarithmic rotated sigmoid height and size frequencies. Seedling height and basal diameter frequency distributions were reverse-J in character. Live tree ages for all species, except white birch (Betula papyrifera Marsh), ranged from 25 to 269 years, and were characterized by all-age frequency distributions. Tree age and size were poorly correlated. On average, balsam fir (Abies balsamea (L.) Mill.) required 62 years to reach breast height (1.3 m), with black spruce (Picea mariana (Mill.) B.S.P.) and white spruce (Picea glauca (Moench) Voss) requiring 40 and 48 years, respectively. Total age of dead standing trees ranged from 45 to 232 years. Reverse-J age frequencies characterized the seedling bank, with balsam fir seedlings present in nearly all age classes up to 110, 120 and 85 years in three sample stands. Seedling size (height and basal diameter)-age relationships were characteristic of decades-long suppression. The combination of tree and seedling bank size and age structure provide strong evidence of quasi-equilibrium, small-scale, gap dynamic old-growth boreal forest stands.
  • McCarthy, University of British Columbia, Forest Sciences Department, 2424 Main Mall, Vancouver, B.C., Canada V6T 1Z4 ORCID ID:E-mail: jmccarthy@jesuits.ca (email)
  • Weetman, University of British Columbia, Forest Sciences Department, 2424 Main Mall, Vancouver, B.C., Canada V6T 1Z4 ORCID ID:E-mail: gw@n.ca
article id 479, category Research article
Ken Olaf Storaunet, Jørund Rolstad, Ivar Gjerde, Vegard S. Gundersen. (2005). Historical logging, productivity, and structural characteristics of boreal coniferous forests in Norway. Silva Fennica vol. 39 no. 3 article id 479. https://doi.org/10.14214/sf.479
Conservation of forest biodiversity has brought about an interest in evaluating the naturalness of forests, and to locate and protect semi-natural and old-growth forests in the Fennoscandian countries. However, it is not always clear how natural these forests really are, and how the past management history has affected their present structural composition. We studied the relationships between cut stumps from historical logging activity (50–100 years ago) and forest structural characteristics of today in a total of 385 0.25 ha plots in three boreal coniferous forests which are parts of National Nature Reserves in Norway. We also studied how forest productivity influenced these relationships. In plots with negligible logging impact we found the amount of living trees, dead wood, and size of the oldest trees mainly to increase with increasing productivity, whereas the age of the oldest trees decreased. The amount of deciduous trees was generally low irrespective of productivity. The intensity of logging did not consistently influence most of these forest structural variables, neither at low- nor at high-productive sites. The only consistent relationship in all study areas was a decreasing amount of dead wood with increasing logging intensity at high-productive sites. Also, the decay class distribution of dead wood was more right-skewed (indicating on-going accumulation of dead wood) the more logging had occurred at high-productive sites. Except from the effects on dead wood, previous logging does not show up as a major determinant of other stand structures of today.
  • Storaunet, Norwegian Forest Research Institute, Høgskolevegen 8, NO-1432 Ås, Norway ORCID ID:E-mail: ken.storaunet@skogforsk.no (email)
  • Rolstad, Norwegian Forest Research Institute, Høgskolevegen 8, NO-1432 Ås, Norway ORCID ID:E-mail:
  • Gjerde, Norwegian Forest Research Institute, Fanaflaten 4, NO-5244 Fana, Norway ORCID ID:E-mail:
  • Gundersen, Norwegian Forest Research Institute, Fanaflaten 4, NO-5244 Fana, Norway ORCID ID:E-mail:
article id 383, category Research article
Lena Gustafsson, Leif Appelgren, Anders Nordin. (2005). Biodiversity value of potential forest fertilisation stands, as assessed by red-listed and ‘signal’ bryophytes and lichens. Silva Fennica vol. 39 no. 2 article id 383. https://doi.org/10.14214/sf.383
In Sweden ca. 20 000 ha forestland is fertilised each year. By using red-listed and ‘signal’ bryophytes and lichens as indicators, we investigated whether forest stands planned for fertilisation have a biodiversity value, and thus if restrictions due to conservation aspects are motivated. Species occurrences were registered in detailed line-transect analysis, with a record size of 10 x 10 m, in 74 coniferous forest stands with a mean age of 57 years in East-Central Sweden. On the 230 ha totally surveyed, 10 red-listed and 37 signal species were found. The mean number of records ha–1 of red-listed bryophytes and lichens was 0.26 ha–1, which is considerably less than previously found in mature production stands and woodland key habitats. Red-listed species were found in 31% of the stands and signal species in 95%. More than 70% of all records of red-listed species and 30% of the records of the signal species were found in moist micro-sites. If rare bryophytes and lichens are to be preserved in fertilisation stands, improved instructions regarding avoidance of important micro-sites are needed.
  • Gustafsson, Swedish University of Agricultural Sciences, Department of Conservation Biology, Box 7002, SE-750 07 Uppsala, Sweden ORCID ID:E-mail: lena.gustafsson@nvb.slu.se (email)
  • Appelgren, Belfragegatan 34H, SE-462 37 Vänersborg, Sweden ORCID ID:E-mail:
  • Nordin, Museum of Evolution, Botany, Norbyvägen 16, SE-752 36 Uppsala, Sweden ORCID ID:E-mail:
article id 405, category Research article
Timo Saksa. (2004). Regeneration process from seed crop to saplings – a case study in uneven-aged Norway spruce-dominated stands in southern Finland. Silva Fennica vol. 38 no. 4 article id 405. https://doi.org/10.14214/sf.405
The dynamics of spruce regeneration, from seed crop to saplings, was studied based on five permanent plots in uneven-aged, spruce-dominated, boreal forest stands, cut with single-tree selection in the beginning of the 1990’s. The annual fluctuation of the spruce seed crop was very similar in uneven-aged and even-aged stands. The correlation between seed crop and number of germinants was significant; but stem number, basal area or volume of the stand did not influence on seedling emergence. The effects of good seed crops were seen as peaks or an increase in the number of germinants and smallest seedlings. The mean number of ‘stabilised’ spruce seedlings (height 11 cm to 130 cm) varied from 6000 ha–1 to over 25 000 spruce seedlings ha–1 from one monitoring plot to another. On a monitoring plot the number of ‘stabilised’ spruce seedlings was stable over time. Neither stand basal area nor stand volume influenced the number of ‘stabilised’ spruce seedlings, but the height of these seedlings was higher on subplots with lower stand volume and smaller basal area. In this study the monitoring period, 5–10 years, was too short to obtain reliable figures for ingrowth, i.e. the transition of seedlings to the sapling stage (h > 130 cm). The adjusted mean ingrowth was 26 stems ha–1 year–1.
  • Saksa, Finnish Forest Research Institute, Suonenjoki Research Station, FI-77600 Suonenjoki, Finland ORCID ID:E-mail: timo.saksa@metla.fi (email)
article id 426, category Research article
Uwe Schmitt, Risto Jalkanen, Dieter Eckstein. (2004). Cambium dynamics of Pinus sylvestris and Betula spp. in the northern boreal forest in Finland. Silva Fennica vol. 38 no. 2 article id 426. https://doi.org/10.14214/sf.426
Wood formation dynamics of pine and birch along a south-north transect in Finnish Lapland were determined by the pinning technique. For all trees at all sites a more or less sigmoid shape of the wood formation intensity is characteristic with a slow beginning, a faster growth in the middle and a decreasing activity towards the end of the vegetation period. Wood formation of pine started at sites 1–3 (southern sites) in the second week of June and at sites 4 and 5 (northern sites) only in the last week of June, whereas wood formation ended within the first half of August. Wood formation of birch started in the second half of June and ended around the beginning of August. First cells were laid down by pine and birch when the temperature sum had reached the level of 85 to 90 degree days and 110 to 120 degree days, respectively. The intensity of wood formation in pine was highest in July, in birch within two weeks in the middle of July. Wood formation in pine lasted for about seven weeks at the southernmost and about six weeks at the northernmost site. In birch, the duration of wood formation was about five weeks at the southernmost site and around three weeks at the other sites.
  • Schmitt, Federal Research Centre for Forestry and Forest Products, Institute for Wood Biology and Wood Protection, and University of Hamburg, Chair for Wood Biology, Leuschnerstr. 91, P. O. Box 800209, D-21002 Hamburg, Germany ORCID ID:E-mail: u.schmitt@holz.uni-hamburg.de (email)
  • Jalkanen, Finnish Forest Research Institute, Rovaniemi Research Station, Box 16, FI-96301 Rovaniemi, Finland ORCID ID:E-mail:
  • Eckstein, Federal Research Centre for Forestry and Forest Products, Institute for Wood Biology and Wood Protection, and University of Hamburg, Chair for Wood Biology, Leuschnerstr. 91, P. O. Box 800209, D-21002 Hamburg, Germany ORCID ID:E-mail:
article id 434, category Research article
Igor Drobyshev, Mats Niklasson, Per Angelstam. (2004). Contrasting tree-ring data with fire record in a pine-dominated landscape in the Komi Republic (Eastern European Russia): recovering a common climate signal. Silva Fennica vol. 38 no. 1 article id 434. https://doi.org/10.14214/sf.434
For the period 1420–1960 we contrasted fire events reconstructed at 14 sites distributed over a 50 km x 50 km area in the central part of the Komi Republic (European Russia) with a set of tree-ring width chronologies of Scots pine (Pinus sylvestris L.), developed for the same area. Our aim was to infer common climatic information contained in tree-ring variables and independently dated fire events with the help of a superposed epoch analysis. The strongest weather–growth link was shown for the latewood width, which was positively correlated with the temperature in April–May and July–August of the current growth season and with previous year precipitation in July–August. Earlywood width was positively affected by previous year precipitation in May and November. The relationship between yearly ring variables and multiple-site fire events was dependent on the seasonal timing of fire events as recorded in the scars. In years with early-season fires (which made up 37% of all fires dated with seasonal resolution) total ring width was significantly narrower. In years with late-season fires (63%) total ring width, earlywood, and latewood width were significantly wider. Years with late-season fires tended to be associated with local highs of the latewood width chronologies over 1400–1960, which implied a link between decadal-scale climate variation and fire regime of the area.
  • Drobyshev, SUFOR Project, Department of Plant Ecology and Systematics, Ecology Building, Sölvegatan 37, Lund University, SE-223 62 Lund, Sweden ORCID ID:E-mail: igor.drobyshev@ekol.lu.se (email)
  • Niklasson, SUFOR Project, Southern Swedish Forest Research Centre, SLU, P.O. Box 49, SE-230 53 Alnarp, Sweden ORCID ID:E-mail:
  • Angelstam, Grimsö Wildlife Research Station, Department of Conservation Biology, Forest Faculty, SLU, SE-730 91 Riddarhyttan, Sweden ORCID ID:E-mail:
article id 431, category Research article
Pauline Stenberg, Miina Rautiainen, Terhikki Manninen, Pekka Voipio, Heikki Smolander. (2004). Reduced simple ratio better than NDVI for estimating LAI in Finnish pine and spruce stands. Silva Fennica vol. 38 no. 1 article id 431. https://doi.org/10.14214/sf.431
Estimation of leaf area index (LAI) using spectral vegetation indices (SVIs) was studied based on data from 683 plots on two Scots pine and Norway spruce dominated sites in Finland. The SVIs studied included the normalised difference vegetation index (NDVI), the simple ratio (SR), and the reduced simple ratio (RSR), and were calculated from Landsat ETM images of the two sites. Regular grids of size 1 km2 with gridpoints placed at 50 m intervals were established at the sites and measurements of LAI using the LAI-2000 instrument were taken at the gridpoints. SVI-LAI relationships were examined at plot scale, where the plots were defined as circular areas of radius 70 m around each gridpoint. Plotwise mean LAI was computed as a weighted average of LAI readings taken around the gridpoints belonging to the plot. Mean LAI for the plots ranged from 0.36 to 3.72 (hemisurface area). All of the studied SVIs showed fair positive correlation with LAI but RSR responded more dynamically to LAI than did SR or NDVI. Especially NDVI showed poor sensitivity to changes in LAI. RSR explained 63% of the variation in LAI when all plots were included (n = 683) and the coefficient of determination rose to 75% when data was restricted to homogeneous plots (n = 381). Maps of estimated LAI using RSR showed good agreement with maps of measured LAI for the two sites.
  • Stenberg, Department of Forest Ecology, P.O. Box 27, FIN-00014 University of Helsinki, Finland ORCID ID:E-mail: pauline.stenberg@helsinki.fi (email)
  • Rautiainen, Department of Forest Ecology, P.O. Box 27, FIN-00014 University of Helsinki, Finland ORCID ID:E-mail:
  • Manninen, Finnish Meteorological Institute, Meteorological research, Ozone and UV radiation research, P.O. Box 503, FIN-00101 Helsinki, Finland ORCID ID:E-mail:
  • Voipio, Finnish Forest Research Institute, Suonenjoki Research Station, FIN-77600 Suonenjoki, Finland ORCID ID:E-mail:
  • Smolander, Finnish Forest Research Institute, Suonenjoki Research Station, FIN-77600 Suonenjoki, Finland ORCID ID:E-mail:
article id 485, category Research article
Helen Uliczka. (2003). Nature conservation efforts by forest owners – intentions and practice in a Swedish case study. Silva Fennica vol. 37 no. 4 article id 485. https://doi.org/10.14214/sf.485
Before a forest operation Swedish forest owners need to fill in a registration form. Since 1994, when a new Swedish Forestry Act came into force, intended nature conservation measures can also be noted on the form. I evaluate 1) if the self-reported nature conservation intentions displayed any trends from 1995 to 2000, and 2) if the intentions were implemented. All forms from these years, in one municipality, were analysed and the stand structure retention was measured on 40 clear-cuts. The intentions, noted as check-marks on the form, showed an increasing trend during these years. However, the increase may be an artefact of changes the form during the time period. The number of check-marks on the forms and the stand structure items actually present on the 40 clear-cuts showed a positive relation. The clear-cuts with ≤ 3 check-marks on the form had lower amounts of the three most common items, than those with ≥ 4 check-marks. To conclude 1) a true increase in the self-reported intentions of the forest owners could not be established; 2) the intentions were generally followed by associated practices on the clear-cuts; 3) the amounts of stand structures retained were probably not enough to reach the biodiversity goal of the Forestry Act. The registration form could be improved to become less open for interpretation and contain quantified recommendations. Self-reported intentions of the forest owners could then possibly be used as indicators of real structural retention, which could facilitate planning and allow for making predictions about the future forests.
  • Uliczka, Swedish University of Agricultural Sciences, Forest Faculty, Department of Conservation Biology, Grimsö Wildlife Research Station, SE-730 91 Riddarhyttan, Sweden ORCID ID:E-mail: helen.uliczka@nvb.slu.se (email)
article id 508, category Research article
Kai Vellak, Jaanus Paal, Jaan Liira. (2003). Diversity and distribution pattern of bryophytes and vascular plants in a boreal spruce forest. Silva Fennica vol. 37 no. 1 article id 508. https://doi.org/10.14214/sf.508
Small scale pattern of bryophyte communities is one of the remarkable sources of diversity in species-poor boreal forests. By means of correlation and general linear model approaches, the relationships between bryophyte vegetation and upper layers, as well as the response of ground and field layer species to several environmental factors, was analyzed in a boreal spruce forest in South-East Estonia. Of the studied factors, the strongest influence on the diversity and spatial distribution of ground and field layer species was found for ‘distance from nearest tree’. Species from different layers react differently to the proximity of trees. Species richness of bryophytes is higher further from trees, whereas more vascular plant species prefer to grow in the vicinity of tree trunks. For bryophyte species richness, the pH of the decay horizon is also important; fewer bryophyte species occur in more acid conditions.
  • Vellak, Institute of Zoology and Botany, Estonian Agricultural University, 181 Riia str., 51014 Tartu, Estonia; Institute of Botany and Ecology, University of Tartu, 40 Lai Str., 51005 Tartu, Estonia ORCID ID:E-mail: kvellak@zbi.ee (email)
  • Paal, Institute of Botany and Ecology, University of Tartu, 40 Lai Str., 51005 Tartu, Estonia ORCID ID:E-mail:
  • Liira, Institute of Botany and Ecology, University of Tartu, 40 Lai Str., 51005 Tartu, Estonia ORCID ID:E-mail:
article id 564, category Research article
Brett G. Purdy, S. Ellen Macdonald, Mark R. T. Dale. (2002). The regeneration niche of white spruce following fire in the mixedwood boreal forest. Silva Fennica vol. 36 no. 1 article id 564. https://doi.org/10.14214/sf.564
Early establishment of white spruce (Picea glauca) in mixedwood boreal forest stands following fire was examined at several times-since-fire (1-, 2-, 4-, 6-, 14-years). Abiotic and biotic conditions in the stands were assessed at two scales, tree plot (5 m x 5 m) and microsite (1 m x 1 m), along with presence, density and height of white spruce seedlings. Germination and survival of seed sown 1- and 4-years post fire were quantified. Survival and growth of nursery-grown seedlings, and mycorrhizal colonization, survival and growth of sterile seedlings, planted 1-year post-fire were assessed. At the tree plot scale, presence of white spruce seedlings 1-year post-fire could be reliably predicted by organic layer depth and distance to and strength of seed source. In contrast, none of the biotic or abiotic factors measured was strongly correlated with occurrence or density of white spruce seedlings 6- and 14- years post-fire. At the microsite scale, seedling recruitment immediately post-fire was limited to a distinct subset of available microsites (greater % cover of downed wood and moss, lower % cover of litter and herbaceous vegetation). Likewise, seedling occurrence in older burns was associated with distinct microsite conditions; although this was more likely an effect of white spruce presence, rather than the cause. Less than 3% of seed sown 1 yr post-fire survived to become 1yr old germinants, survival was 41% over the next three years. Availability of suitable regeneration microsites declines rapidly with time-since-fire; less than 0.3% of seed sown 4 yrs post-fire survived one year. High rates of mycorrhizal colonization were found on white spruce seedlings planted 1-year post-fire, including early and late stage fungal species. Microsite characteristics were only weakly correlated with mycorrhizal fungal communities. We propose that immediate post-fire recruitment of white spruce is a key process in mixedwood boreal succession.
  • Purdy, Dept. of Renewable Resources, University of Alberta, Edmonton, AB, Canada T6G 2E3 ORCID ID:E-mail:
  • Macdonald, Dept. of Renewable Resources, University of Alberta, Edmonton, AB, Canada T6G 2E3 ORCID ID:E-mail: ellen.macdonald@ualberta.ca (email)
  • Dale, Dale, Dept. of Biological Sciences, University of Alberta, Edmonton, AB, Canada T6G 2E9 ORCID ID:E-mail:
article id 561, category Research article
Karen A. Harper, Yves Bergeron, Sylvie Gauthier, Pierre Drapeau. (2002). Post-fire development of canopy structure and composition in black spruce forests of Abitibi, Québec: a landscape scale study. Silva Fennica vol. 36 no. 1 article id 561. https://doi.org/10.14214/sf.561
Fire reconstruction and forest inventory maps provided an opportunity to study changes in stand-level characteristics following fire using a data set comprised of all forest stands of fire origin in an area of over 10 000 km2. We assigned the date of the most recent fire occurrence to over 31 000 forest stands in an ecoforestry database. We categorized stands on different substrates into age classes to investigate differences in canopy composition, cover and height, and incidence of secondary disturbance. Stands with over 75% Picea mariana (Mill.) BSP dominated all age classes on organic sites. On other substrates, there was a change in canopy composition from deciduous stands and stands dominated by Pinus banksiana Lamb. to Picea mariana stands after about 100 yr. This transition was later for xeric sites. After a peak in canopy cover and height at about 100 yr, there was a decrease in the area occupied by stands with dense, tall canopies. Structural development was slower on less productive sites. There was little incidence of spruce budworm outbreaks. Partial disturbance by windthrow coincided with canopy break-up at 100 yr, but appeared to have little effect on overall canopy structure in later stages. Structural diversity was independent of compositional diversity; on organic sites, stands with similar composition had different canopy structure. Diversity of stands with different composition and structure was greatest in the first 150 yr following fire. Maintaining stands in different stages of structural development on the landscape would serve to maintain regional biodiversity.
  • Harper, Université de Québec à Montréal, Groupe de recherche en écologie forestière interuniversitaire, CP 8888, succ. A, Montréal, QC, Canada H3C 3P8 ORCID ID:E-mail: c1444@er.uqam.ca (email)
  • Bergeron, NSERC-UQAT-UQAM, Industrial Chair in sustainable forest management, CP 8888, succ. Centre-Ville, Montréal, QC, Canada H3C 3P8 ORCID ID:E-mail:
  • Gauthier, Canadian Forest Service, Laurentian Forestry Centre, P.O. Box 3800, Sainte-Foy, QC, Canada G1V 4C7 ORCID ID:E-mail:
  • Drapeau, Université de Québec à Montréal, Groupe de recherche en écologie forestière interuniversitaire, CP 8888, succ. A, Montréal, QC, Canada H3C 3P8 ORCID ID:E-mail:
article id 558, category Research article
Tuomo Wallenius. (2002). Forest age distribution and traces of past fires in a natural boreal landscape dominated by Picea abies. Silva Fennica vol. 36 no. 1 article id 558. https://doi.org/10.14214/sf.558
Forest age distribution and occurrence of traces of past fires was studied in a natural Picea abies -dominated landscape in the Onega peninsula in north-west Russia. Forest age (maximum tree age) was determined and charcoal and fire scars were searched for in 43 randomly located study plots. In 70% of the study plots (30/43) trees older than 200 years existed. The largest 50-year age class consisted of plots with 251–300 year old forests. Traces of fires were found in all types of study plots, in forests on mineral soil as well as on peatlands. However, fire has been a rare disturbance factor, as traces of fires could not be found in 35% of the study plots (15/43). Estimated from the forest age class distribution, the fire rotation time for the whole area has been at least 300 years, but possibly considerably longer. This fire rotation time is much longer than fire history studies (largely based on examination of fire scars) commonly have reported for the average time between successive fires in Fennoscandia and Northwest Russia. The results suggest that the often stated generalisations about the importance and natural frequency of fire disturbance in boreal forests do not apply in landscapes dominated by Picea abies.
  • Wallenius, Department of Ecology and Systematics, University of Helsinki, P.O. Box 56, FIN-00014 University of Helsinki, Finland ORCID ID:E-mail: tuomo.wallenius@helsinki.fi (email)
article id 556, category Research article
Timo Kuuluvainen, Juha Mäki, Leena Karjalainen, Hannu Lehtonen. (2002). Tree age distributions in old-growth forest sites in Vienansalo wilderness, eastern Fennoscandia. Silva Fennica vol. 36 no. 1 article id 556. https://doi.org/10.14214/sf.556
The age and size of trees was sampled and measured on eight sample plots (0.2 ha each) within a Pinus sylvestris -dominated boreal forest landscape in Vienansalo wilderness, Russian Karelia. The fire history of these plots was obtained from a previous dendrochronological study. All the studied sample plots showed a wide and uneven distribution of tree ages, but the shape of the age distributions of trees as well as tree species composition varied substantially. Trees over 250 years of age occurred in every studied plot, despite its small size. This suggests that old Pinus were common and rather evenly distributed in the landscape matrix. The oldest Pinus tree was 525 years of age. The correlations between tree age and size were often weak or even nil. In Pinus the correlation between age and diameter was stronger than that between age and height. In the dominant tree species Pinus and Picea, the largest trees were not the oldest trees. The tree age distributions together with the fire history data indicated that the past fires have not been stand replacing, as many of the older Pinus had survived even several fires. Tree age classes that had regenerated after the last fire were most abundant and dominated by Picea and/or deciduous trees, while the trees established before the last fire were almost exclusively Pinus. The results suggest that periodic occurrence of fire is important for the maintenance of the Pinus-dominated landscape. This is because fire kills most Picea and deciduous trees and at the same time enhances conditions for Pinus regeneration, facilitated by available seed from the continuous presence of old fire-tolerant Pinus trees.
  • Kuuluvainen, Department of Forest Ecology, University of Helsinki, P.O. Box 24, FIN-00014 University of Helsinki, Finland ORCID ID:E-mail: timo.kuuluvainen@helsinki.fi (email)
  • Mäki, Department of Forest Ecology, University of Helsinki, P.O. Box 24, FIN-00014 University of Helsinki, Finland ORCID ID:E-mail:
  • Karjalainen, Department of Forest Ecology, University of Helsinki, P.O. Box 24, FIN-00014 University of Helsinki, Finland ORCID ID:E-mail:
  • Lehtonen, Faculty of Forestry, University of Joensuu, P.O. Box 24, FIN-80101 Joensuu, Finland ORCID ID:E-mail:
article id 616, category Research article
Markus Lindholm, Hannu Lehtonen, Taneli Kolström, Jouko Meriläinen, Matti Eronen, Mauri Timonen. (2000). Climatic signals extracted from ring-width chronologies of Scots pines from the northern, middle and southern parts of the boreal forest belt in Finland. Silva Fennica vol. 34 no. 4 article id 616. https://doi.org/10.14214/sf.616
Climatic signals were extracted from ring-width chronologies of Scots pines (Pinus sylvestris L.) from natural stands of the northern, middle, and southern parts of the boreal forest belt in Finland. The strength of the common growth signals (forcing factors) were quantified as a function of time. This was achieved by mean inter-series correlations, calculated over a moving 30-year window, both within and between the regional chronologies. Strong regional signals and also evidence for common forcings were found, especially between northern and central, central and eastern, as well as central/eastern and southern chronologies. Response function analyses revealed that growing season temperatures govern the growth rates of northern pines, while towards south, pine growth becomes less affected by temperatures, and more affected by e.g. precipitation. During some periods, growing conditions seem to have been favorable in the south, while they have been unfavorable in the north (growth inversions). Going from the north to the south, the variability of radial growth clearly decreases, and the variance of ring-width series becomes smaller. Growth variability in the four regions was compared during the common interval of the chronologies, from 1806 to 1991. The spectral densities of the northern, central, eastern and southern chronologies were also compared as functions of frequency, viz. cycles per year. The variance is much greater and there is more periodic behavior in the north than in the south in high, medium, as well as lower frequencies.
  • Lindholm, Saima Centre for Environmental Sciences, University of Joensuu, Linnankatu 11, FIN-57130 Savonlinna, Finland ORCID ID:E-mail:
  • Lehtonen, Finnish Forest Research Institute, Joensuu Research Station, Box 68, FIN-80101 Joensuu, Finland ORCID ID:E-mail:
  • Kolström, Finnish Forest Research Institute, Joensuu Research Station, Box 68, FIN-80101 Joensuu, Finland ORCID ID:E-mail:
  • Meriläinen, Saima Centre for Environmental Sciences, University of Joensuu, Linnankatu 11, FIN-57130 Savonlinna, Finland ORCID ID:E-mail:
  • Eronen, Department of Geology, Division of Geology and Palaeontology, Box 11, FIN-00014 University of Helsinki, Finland ORCID ID:E-mail:
  • Timonen, Finnish Forest Research Institute, Rovaniemi Research Station, Box 16, FIN-96301 Rovaniemi, Finland ORCID ID:E-mail:
article id 625, category Research article
Hans-Örjan Nohrstedt. (2000). Effects of soil scarification and previous N fertilisation on pools of inorganic N in soil after clear-felling of a Pinus sylvestris (L.) stand. Silva Fennica vol. 34 no. 3 article id 625. https://doi.org/10.14214/sf.625
Previous analyses of soil water beneath mounds resulting from scarification have implied that this forestry measure increases leaching of inorganic N. However, more recent soil-water studies have not confirmed this assumption. The soil study presented here examined the pools of inorganic N in different microsites emanating from a simulated disc trenching, i. e. the mound with underlying soil, the furrow bottom and the undisturbed soil. The study was made five years after scarification. The mound itself with underlying soil had a larger pool of inorganic N than the undisturbed soil. This was mainly because of an increase in the embedded humus layer, thus implying a larger net N mineralisation and/or lower losses. However, when pools of inorganic N per hectare were calculated, taking into consideration that a scarified area comprises 25% mounds, 25% furrows and 50% undisturbed soil, there was no increase in pools of inorganic N when compared with an area not subjected to scarification. This observation supports the finding of the more recent soil-water studies mentioned, i. e., that leaching seems not to be influenced by soil scarification. The scarification was made as a split-plot treatment on main-plots in an old experiment with different N doses. Thus, the effect of the previous N fertilisation could also be evaluated. Two N doses were tested beside the unfertilised control: 720N (3 x 240 kg N ha–1 yr–1) and 1800N (3 x 600 kg N ha–1 yr–1). The last fertiliser application was made six years before the clearcutting and 13 years before the soil sampling. The previously fertilised main-plots had larger pools of inorganic N than the control plots.
  • Nohrstedt, The Forestry Research Institute of Sweden, Uppsala Science Park, SE-751 83 Uppsala, Sweden ORCID ID:E-mail: hans-orjan.nohrstedt@skogforsk.se (email)

Category: Review article

article id 411, category Review article
Arthur Groot, Sylvie Gauthier, Yves Bergeron. (2004). Stand dynamics modelling approaches for multicohort management of eastern Canadian boreal forests. Silva Fennica vol. 38 no. 4 article id 411. https://doi.org/10.14214/sf.411
The objective of this paper is to discuss approaches and issues related to modelling stand dynamics for multi-cohort forest management in eastern Canadian boreal forests. In these forests, the interval between wildfires can be rather long, and the development of natural forest stands may include the establishment, growth and mortality of several cohorts of trees. Later cohorts are characterised by increasing structural complexity, including spatial heterogeneity and irregular tree size distribution. A multi-cohort forest management framework has been proposed to maintain this complexity, and associated biodiversity, on the landscape. Multi-cohort forest management planning requires forecasts of the development of stands with complex structure in response to silvicultural treatment and to natural disturbance, but current stand dynamics models in the region are applicable mainly to even-aged mono-specific stands. Possible modelling approaches for complex stands include i) the adaptation of current whole-stand growth and yield models, ii) distance-independent, empirically-derived individual-tree models, such as the USDA Forest Service Forest Vegetation Simulator, and iii) distance-dependent, empirically-derived or process-oriented individual-tree models. We conclude that individual-tree models are needed because observational data for fitting whole-stand models are not available for the full array of silvicultural treatments and natural disturbances encompassed by multi-cohort forest management. Predictive accuracy is a concern with individual-tree models, and the incorporation of coarse-scale constraints into these models is a promising means to control error.
  • Groot, Great Lakes Forestry Centre, Canadian Forest Service, 1219 Queen St. E., Sault Ste. Marie, ON, P6A 2E5, Canada ORCID ID:E-mail: agroot@nrcan.gc.ca (email)
  • Gauthier, Laurentian Forestry Centre, Canadian Forest Service, 1055 du P.E.P.S., P.O. Box 3800, Sainte-Foy, QC, G1V 4C7, Canada ORCID ID:E-mail:
  • Bergeron, University of Quebec at Abitibi-Temiscamingue, 445 Boul de l’Université, Rouyn-Noranda, QC, J9X 5E4, Canada ORCID ID:E-mail:
article id 551, category Review article
Anders Dahlberg. (2002). Effects of fire on ectomycorrhizal fungi in Fennoscandian boreal forests. Silva Fennica vol. 36 no. 1 article id 551. https://doi.org/10.14214/sf.551
Fire, the primary natural disturbance factor in Fennoscandian boreal forests, is considered to have exerted major selection pressure on most boreal forest organisms. However, recent studies show that few ectomycorrhizal (EM) fungi appear to have evolved post-fire adaptations, no succession of EM fungi following fire is apparent after low intensity fires, and only two EM fungal taxa exclusively fruit at post-fire conditions. In this paper I review the present knowledge of effects of forest fire on EM fungal communities in Fennscandian boreal forests, put into perspective by a comparison from other parts of the world. Characteristically, these boreal forests consist of less than a handful of tree species, e.g. Scots pine and Norway spruce, while the below ground communities of EM fungi is impressively species rich with presently more than 700 known taxa. Commonly, forest fires in Fennoscandia have been of low intensity, with a considerable portion of the trees surviving and the organic humus layer partly escaping combustion. Hence, EM fungi appear to largely have evolved under conditions characterised by a more or less continuous presence of their hosts. In fact, the composition of EM fungi within a forest appear be more variable due to spatial variation than due to wildfire. However, in areas with high intensity burns and high tree mortality, most EM fungi may locally be killed. Thus, the legacy of EM fungi following wildfire depends on the survival of trees, which determine the potential for mycorrhizal growth, and the combustion and heating of the organic soil, which directly correlate to mortality of mycorrhizas. The questions if and to what degree fires may be of significance for yet unidentified spatiotemporal dynamics of EM fungal populations and communities are discussed. Recent experiments indicate a few EM fungi are favoured by high intensity burn conditions whereas others disappear. The consequences of wildfires in temperate conifer forests differ considerably from those in boreal forests. Wildfires in temperate conifer forests are typically high intensity stand-replacing fires that cause a total combustion of organic layers. Subsequently, pre-fire EM fungal communities are largely eradicated and a succession of post-fire EM fungi is initiated.
  • Dahlberg, Department of Forest Mycology and Pathology, Swedish University of Agricultural Sciences, P.O. Box 7026, SE-750 07 Uppsala, Sweden ORCID ID:E-mail: anders.dahlberg@artdata.slu.se (email)
article id 550, category Review article
Lars Edenius, Margareta Bergman, Göran Ericsson, Kjell Danell. (2002). The role of moose as a disturbance factor in managed boreal forests. Silva Fennica vol. 36 no. 1 article id 550. https://doi.org/10.14214/sf.550
We review the interactions between moose (Alces alces) and native tree species in Fennoscandia. The Fennoscandian boreal forests have been intensively managed for wood production over decades. Moose population density is also relatively high in these northern forests. Forest management affects habitat characteristics and food resources from regeneration to final harvest, with the most significant effects occurring early in the stand development. The plant-animal interactions found in such a situation may be different from what has been observed in natural boreal forests with low densities of moose (e.g. in North America). The strong focus on Scots pine (Pinus sylvestris) in forest regeneration in conjunction with a homogenisation of the landscape structure by clear-cutting has favoured moose. Forest development is controlled by man from regeneration to final harvest, and in relation to human-induced disturbances the disturbance by moose is relatively small, but occurs on different spatial levels. At the landscape level, the most prominent effects of moose seem to be suppression and/or redistribution of preferred browse species. At the forest stand level moose primarily induce spatial heterogeneity by browsing patchily and exploiting existing gaps. At the tree level, moose damage trees and lower timber quality, but also create substrate types (e.g. dead and dying wood) valuable for many organisms. Co-management of moose and forest requires good monitoring programmes for both plants and animals, as well as extensive ecological knowledge on the relations between moose and their food plants on different spatial levels.
  • Edenius, SLU, Department of Animal Ecology, SE-901 83 Umeå, Sweden ORCID ID:E-mail: lars.edenius@szooek.slu.se (email)
  • Bergman, SLU, Department of Animal Ecology, SE-901 83 Umeå, Sweden ORCID ID:E-mail:
  • Ericsson, SLU, Department of Animal Ecology, SE-901 83 Umeå, Sweden ORCID ID:E-mail:
  • Danell, SLU, Department of Animal Ecology, SE-901 83 Umeå, Sweden ORCID ID:E-mail:
article id 549, category Review article
Andrei Gromtsev. (2002). Natural disturbance dynamics in the boreal forests of European Russia: a review. Silva Fennica vol. 36 no. 1 article id 549. https://doi.org/10.14214/sf.549
In the European part of the Russian boreal zone the dynamics of pristine forests (taiga) has been studied by several generations of researchers. Many studies have examined the patterns and role of fire, windthrow, insect outbreaks and other natural disturbances. An attempt is made to provide a brief review of these studies. The reviewed studies show that lightning strikes were the only natural source of fires in taiga. The frequency of fires varied in various types of pristine landscape from 1–2 per century to 1–2 per millennium. Fires maintained a dynamic equilibrium between compositionally different forest communities or their certain ratio and areal occurrence. Fires favored the regeneration and recovery of pine forests and prevented the replacement of shade-intolerant species (e.g. pine) by shade-tolerant ones (e.g. spruce). Taiga forests generally displayed a mosaic pattern that varied from pioneer plant communities, growing in open burns, to climax communities that were extremely seldom affected by fire. The reviewed studies suggest that fires were a powerful ecological factor in pristine taiga, being largely responsible for the structure and spontaneous dynamics of forest communities. Windfalls were also common in pristine taiga landscapes and they regulated spontaneous dynamics in a gap-mosaic regime, which is most characteristic of spruce forests.
  • Gromtsev, Forest Research Institute, Karelian Research Centre of the Russian Academy of Sciences, P.O. Box 185610, Petrozavodsk, Pushkin st. 11, Russia ORCID ID:E-mail: gromtsev@karelia.ru (email)
article id 548, category Review article
Kevin C. Ryan. (2002). Dynamic interactions between forest structure and fire behavior in boreal ecosystems. Silva Fennica vol. 36 no. 1 article id 548. https://doi.org/10.14214/sf.548
This paper reviews and synthesizes literature on fire as a disturbance factor in boreal forests. Spatial and temporal variation in the biophysical environment, specifically, vegetative structure, terrain, and weather lead to variations in fire behavior. Changes in slope, aspect, elevation, and soil affect site energy and water budgets and the potential plant community. These terrain features also have a major influence on fire-caused disturbance through their role in determining moisture conditions and flammability of fuels on hourly, seasonal, and successional time-scales. On fine time scales (minutes to hours), changes in weather, specifically wind and relative humidity, significantly affect a fire’s intensity and aboveground effects. Normal seasonal changes in dryness and periodic drought influence fire intensity and severity principally by affecting the depth of burn and belowground effects. On decades-long time scales changes in vegetative structure affect the mass of fuel available for burning and therefore the potential energy that can be released during a fire. The severity of fire varies in time and space depending not only on the biophysical environment, but also on the location on the fire’s perimeter (head vs. flank vs. rear). Spatial and temporal variation in severity within a fire can have long-lasting impacts on the structure and species composition of post-fire communities and the potential for future disturbances. Characteristic temperature histories of ground, surface, and crown fires are used to illustrate variations in fire severity. A soil-heating model is used to illustrate the impact of varying depth of burn on the depth at which various fire effects occur in the soil profile. A conceptual model is presented for the effects of fire severity on fire-plant regeneration interactions. The conceptual model can be used by restoration ecologists to evaluate the differential effects of controlled or prescribed fires and wildfires and to plan and implement fire treatments to conserve biodiversity.
  • Ryan, USDA Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory, P.O. Box 8089, Missoula, Montana 59807, USA ORCID ID:E-mail: kryan@fs.fed.us (email)

Category: Research note

article id 10009, category Research note
Jānis Donis, Māra Kitenberga, Guntars Šņepsts, Edgars Dubrovskis, Āris Jansons. (2018). Factors affecting windstorm damage at the stand level in hemiboreal forests in Latvia: case study of 2005 winter storm. Silva Fennica vol. 52 no. 4 article id 10009. https://doi.org/10.14214/sf.10009
Highlights: In hemiboreal forests in Latvia, dominant tree species, admixture of spruce in canopy-layer, mean height, timing of thinnings, upwind forest edges and wind gusts had significant effect on windstorm damage occurrence at stand-level; Stands on peat soils were more damaged than stands on mineral soils; Tree species composition of canopy-layer was not statistically significant in the model.

In managed European hemiboreal forests, windstorms have a notable ecological and socio-economic impact. In this study, stand properties affecting windstorm damage occurrence at the stand-level were assessed using a Generalized Linear Mixed model. After 2005 windstorm, 5959 stands dominated by birch (Betula spp.), Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) Karst.), with mean height > 10 m were inventoried. Windstorm damage was positively associated with spruce and pine-dominated stands, increasing mean height, fresh forest edges, decreasing time since the last thinning and stronger wind gusts. Tree species composition – mixed or monodominant – was not statistically significant in the model; while, the admixture of spruce in the canopy layer was positively associated with higher windstorm damage. Stands on peat soils were more damaged than stands on mineral soils. Birch stands were more damaged than pine stands. This information could be used in forest management planning, selection of silvicultural treatments to increase forest resilience to natural disturbances.

  • Donis, Latvian State Forest Research Institute “Silava”, Rigas 111, Salaspils, Latvia, LV-2169 ORCID ID:E-mail: janis.donis@silava.lv (email)
  • Kitenberga, Latvian State Forest Research Institute “Silava”, Rigas 111, Salaspils, Latvia, LV-2169 ORCID ID:E-mail: mara.kitenberga@gmail.com
  • Šņepsts, Latvian State Forest Research Institute “Silava”, Rigas 111, Salaspils, Latvia, LV-2169 ORCID ID:E-mail: guntars.snepsts@silava.lv
  • Dubrovskis, Latvia University of Life Sciences and Technologies, Liela iela 2, Jelgava, Latvia, LV-3001 ORCID ID:E-mail: edgars.dubrovskis@llu.lv
  • Jansons, Latvian State Forest Research Institute “Silava”, Rigas 111, Salaspils, Latvia, LV-2169 ORCID ID:E-mail: aris.jansons@silava.lv
article id 9899, category Research note
Linda Robalte, Diāna Jansone, Didzis Elferts, Roberts Matisons, Āris Jansons. (2018). Bilberry ramet dimensions in relation to stand age in oligotrophic conditions in Latvia. Silva Fennica vol. 52 no. 1 article id 9899. https://doi.org/10.14214/sf.9899
Highlights: Bilberry ramet dimensions (age, diameter, height) and their structural diversity, as well as cover, increased with stand age; Active rejuvenation of ramets was observed in younger stands; The oldest bilberry ramets (>10 years of age) occurred in stands older than 70 years.

Dwarf shrub layer is an important component of boreal and hemiboreal forest ecosystems that has received little attention, particularly regarding its structural diversity, which, however, could serve as an additional proxy for habitat quality. Dimensions of bilberry (Vaccinium myrtillus L.) ramets were assessed in two sites in Latvia covered by dry oligotrophic Scots pine (Pinus sylvestris L.) stands 10–230 years of age. In total, 20 sampling plots (10×10 m) with 156 subplots (1×1 m) were sampled and 630 bilberry ramets analysed. The dimensions of ramets (age, diameter, and height) and cover of bilberry increased with stand age. The age of the studied ramets ranged 2–13 years; 5–6 years-old ramets were most frequent in all stands. The skewness of the distribution of the ramet dimensions shifted with stand age, leaning towards the higher values. Lower structural diversity of ramets was observed in stands 50–100 years of age. The highest diversity of ramet age structure occurred in stands younger than 150 years, whereas the oldest and largest ramets mostly occurred in the older stands (>150 years). Considering structural diversity of ramets, recovery of bilberry after stand-replacing disturbance (e.g. clearcut) was a continuous process, similarly to that observed in tree layer.

  • Robalte, Latvian State Forest Research Institute “Silava”, 111 Rigas Str., LV 2169, Salaspils, Latvia ORCID ID:E-mail: robalte.l@gmail.com (email)
  • Jansone, Latvian State Forest Research Institute “Silava”, 111 Rigas Str., LV 2169, Salaspils, Latvia; University of Latvia, Faculty of Biology, Jelgavas Str. 1, LV 1004, Riga, Latvia ORCID ID:E-mail: diana.jansone13@gmail.com
  • Elferts, Latvian State Forest Research Institute “Silava”, 111 Rigas Str., LV 2169, Salaspils, Latvia; University of Latvia, Faculty of Biology, Jelgavas Str. 1, LV 1004, Riga, Latvia ORCID ID:E-mail: didzis.elferts@lu.lv
  • Matisons, Latvian State Forest Research Institute “Silava”, 111 Rigas Str., LV 2169, Salaspils, Latvia ORCID ID:E-mail: roberts.matisons@silava.lv
  • Jansons, Latvian State Forest Research Institute “Silava”, 111 Rigas Str., LV 2169, Salaspils, Latvia ORCID ID:E-mail: aris.jansons@silava.lv
article id 1321, category Research note
Sofia Bäcklund, Mari T. Jönsson, Joachim Strengbom, Göran Thor. (2015). Composition of functional groups of ground vegetation differ between planted stands of non-native Pinus contorta and native Pinus sylvestris and Picea abies in northern Sweden. Silva Fennica vol. 49 no. 2 article id 1321. https://doi.org/10.14214/sf.1321
Highlights: Differences in ground vegetation patterns can be linked to tree species, forest stand age and differences in canopy cover; Vascular plant cover was higher in stands of P. contorta than in stands of both native tree species; The overall differences and similarities between P. contorta and the two native conifers were not consistent over the different age classes.
Intensified forestry increases the interest in replacing native tree species with fast growing non-native species. However, consequences for native biodiversity and ecosystem functioning are poorly understood. We compared cover and composition of major functional groups of ground vegetation between planted stands of non-native Pinus contorta Dougl. var. latifolia Engelm. and native conifers Pinus sylvestris L. and Picea abies (L.) H. Karst. in northern boreal Sweden. We quantified the ground cover of lichens, bryophytes, vascular plants and ground without vegetation (bare ground) in 96 stands covering three different age classes (15, 30 and 85 years old). Our study revealed differences in ground vegetation patterns between non-native and native managed forests, and that these differences are linked to stand age and differences in canopy cover. Total vascular plant cover increased with increasing stand age for all tree species, with P. contorta stands having higher cover than both native conifers. The ground cover of lichens was, although generally low, highest in stands of Pinus sylvestris. P. abies stands had a lower cover of vascular plants, but bare ground was more common compared with P. contorta. Our results suggest that the use of P. contorta as an alternative tree species in Fennoscandian forestry will influence native ground vegetation patterns. This influence is likely to change with time and future research should consider both temporal and landscape-scale effects from shifting tree-species dominance to Pinus contorta and other non-native tree species.
  • Bäcklund, Department of Ecology, Swedish University of Agricultural Sciences, P.O. Box 7044, SE-750 07 Uppsala, Sweden ORCID ID:E-mail: sofia.backlund@slu.se (email)
  • Jönsson,  The Swedish Species Information Centre, P.O. Box 7007, SE-750 07 Uppsala, Sweden ORCID ID:E-mail: mari.jonsson@slu.se
  • Strengbom, Department of Ecology, Swedish University of Agricultural Sciences, P.O. Box 7044, SE-750 07 Uppsala, Sweden ORCID ID:E-mail: joachim.strengbom@slu.se
  • Thor, Department of Ecology, Swedish University of Agricultural Sciences, P.O. Box 7044, SE-750 07 Uppsala, Sweden ORCID ID:E-mail: goran.thor@slu.se
article id 228, category Research note
Aku Riihelä, Terhikki Manninen. (2008). Measuring the vertical albedo profile of a subarctic boreal forest canopy. Silva Fennica vol. 42 no. 5 article id 228. https://doi.org/10.14214/sf.228
The validation of airborne and satellite-derived albedo measurements suffers from the fact that the surface albedo of forest is difficult to measure in-situ over large areas. The goal of this study is to examine whether or not the estimation of the surface albedo of a forest stand from ground level measurements is possible. In addition, knowledge about the vertical behavior of albedo, and therefore transmitted solar radiation, is important in the modeling of interactions of sunlight with the forest canopy. Such modeling is useful for forest growth estimations among other things. To achieve these goals, an albedometer set-up capable of vertical albedo profiling has been used to obtain data from a boreal forest stand in Northern Finland during periods in summer 2006 and winter 2007. The results show a strong relationship between the data and fitted power-law regression curves. Power-law regression fits best likely because of the radiation transmission characteristics of boreal forest.
  • Riihelä, Finnish Meteorological Institute, P.O. Box 503, FI-00200 Helsinki, Finland ORCID ID:E-mail: aku.riihela@fmi.fi (email)
  • Manninen, Finnish Meteorological Institute, P.O. Box 503, FI-00200 Helsinki, Finland ORCID ID:E-mail:
article id 678, category Research note
Ian A. Nalder, Ross W. Wein. (1998). A new forest floor corer for rapid sampling, minimal disturbance and adequate precision. Silva Fennica vol. 32 no. 4 article id 678. https://doi.org/10.14214/sf.678
We describe an effective and inexpensive device for sampling forest floors. It is based on a rechargeable, battery-powered drill that drives a sharpened steel coring tube. The corer is simple to fabricate, is lightweight (3.5 kg) and can be used easily by one person to obtain intact, natural volume cores of the forest floor. It has been used extensively to obtain samples in 114 boreal forest stands of western Canada. We found that coefficients of variation were typically 30% for forest floor organic matter and bulk density, and tended to be higher in Pinus banksiana stands than in Picea glauca and Populus tremuloides. Ten samples per stand gave adequate precision for a study of forest floor dynamics and autocorrelation did not appear to be a problem with five-metre sampling intervals. In addition to sampling forest floors, the corer has proven suitable for sampling moss and lichen layers and mineral soil down to about 20 cm. A similar powered system can also be used for increment boring of trees.
  • Nalder, University of Alberta, Department of Renewable Resources, 442 Earth Sciences Building, Edmonton, Alberta, Canada T6G 2E3 ORCID ID:E-mail: inalder@gpu.srv.ualberta.ca (email)
  • Wein, University of Alberta, Department of Renewable Resources, 442 Earth Sciences Building, Edmonton, Alberta, Canada T6G 2E3 ORCID ID:E-mail:

Category: Discussion article

article id 573, category Discussion article
Matti Koivula, Jari Niemelä. (2002). Boreal carabid beetles (Coleoptera, Carabidae) in managed spruce forests – a summary of Finnish case studies. Silva Fennica vol. 36 no. 1 article id 573. https://doi.org/10.14214/sf.573
  • Koivula, Department of Ecology and Systematics, Division of Population Biology, P.O. Box 65, FIN-00014 University of Helsinki, Finland ORCID ID:E-mail: matti.koivula@helsinki.fi (email)
  • Niemelä, Department of Ecology and Systematics, Division of Population Biology, P.O. Box 65, FIN-00014 University of Helsinki, Finland ORCID ID:E-mail:

Category: Article

article id 7289, category Article
P. S. Tikka. (1934). Über die Stockfäule der Nadelwälder Nord-Suomis (-Finnlands). Acta Forestalia Fennica vol. 40 no. 12 article id 7289. https://doi.org/10.14214/aff.7289
English title: Butt rot in the coniferous forests of northern Finland.

There are two fungi that cause butt rot: Fomitopsis annosa and Bjerkandera borealis. The losses they cause in pine forests are relatively mild, the share of rotten trees is between 6 and 12 % and the rot is restricted to the butt end of the tree.

In forests dominated with spruce the losses to timber are more notable. The share of trees infected with butt rot is between 10 and 40 % and of the volume at least 12 per cent. The more barren the heath forest site the greater the defect caused by decay. In the forests on peatland the pine swamps and spruce moors are the most affected.

The PDF contains a summary in Finnish.  

  • Tikka, ORCID ID:E-mail:
article id 7289, category Article
P. S. Tikka. (1934). Über die Stockfäule der Nadelwälder Nord-Suomis (-Finnlands). Acta Forestalia Fennica vol. 40 no. 12 article id 7289. https://doi.org/10.14214/aff.7289
English title: Butt rot in the coniferous forests of northern Finland.

There are two fungi that cause butt rot: Fomitopsis annosa and Bjerkandera borealis. The losses they cause in pine forests are relatively mild, the share of rotten trees is between 6 and 12 % and the rot is restricted to the butt end of the tree.

In forests dominated with spruce the losses to timber are more notable. The share of trees infected with butt rot is between 10 and 40 % and of the volume at least 12 per cent. The more barren the heath forest site the greater the defect caused by decay. In the forests on peatland the pine swamps and spruce moors are the most affected.

The PDF contains a summary in Finnish.  

  • Tikka, ORCID ID:E-mail:
article id 5606, category Article
Pekka E. Kauppi, Pekka Hänninen, Helena M Henttonen, Antti Ihalainen, Eino Lappalainen, Maximilian Posch, Michael Starr, Pekka Tamminen. (1997). Carbon reservoirs in peatlands and forests in the boreal regions of Finland. Silva Fennica vol. 31 no. 1 article id 5606. https://doi.org/10.14214/sf.a8507

The carbon reservoir of ecosystems was estimated based on field measurements for forests and peatlands on an area in Finland covering 263,000 km2 and extending about 900 km across the boreal zone from south to north. More than two thirds of the reservoir was in peat, and less than ten per cent in trees. Forest ecosystems growing on mineral soils covering 144,000 km2 contained 10–11 kg C m-2 on an average, including both vegetation (3.4 kg C m-2) and soil (uppermost 75 cm; 7.2 kg C m-2). Mire ecosystems covering 65,000 km2 contained an average of 72 kg C m-2 as peat. For the landscape consisting of peatlands, closed and open forests, and inland water, excluding arable and built-up land, a reservoir of 24.6 kg C m-2 was observed. This includes the peat, forest soil and tree biomass. This is an underestimate of the true total reservoir, because there are additional unknown reservoirs in deep soil, lake sediments, woody debris, and ground vegetation. Geographic distributions of the reservoirs were described, analysed and discussed. The highest reservoir, 35–40 kg C m-2, was observed in sub-regions in central western and north western Finland. Many estimates given for the boreal carbon reservoirs have been higher than those of ours. Either the Finnish environment contains less carbon per unit area than the rest of the boreal zone, or the global boreal reservoir has earlier been overestimated. In order to reduce uncertainties of the global estimates, statistically representative measurements are needed especially on Russian and Canadian peatlands.

  • Kauppi, ORCID ID:E-mail:
  • Hänninen, ORCID ID:E-mail:
  • Henttonen, ORCID ID:E-mail:
  • Ihalainen, ORCID ID:E-mail:
  • Lappalainen, ORCID ID:E-mail:
  • Posch, ORCID ID:E-mail:
  • Starr, ORCID ID:E-mail:
  • Tamminen, ORCID ID:E-mail:
article id 5567, category Article
Pekka Punttila, Yrjö Haila. (1996). Colonisation of a burned forest by ants in the southern Finnish boreal forest. Silva Fennica vol. 30 no. 4 article id 5567. https://doi.org/10.14214/sf.a8502

The colonisation of a burned clear-cut by ants in southern Finland was monitored using pitfall traps, artificial nest sites, and direct nest sampling from the ground and stumps. Clearcutting and fire seemed to have destroyed wood-ant colonies (Formica rufa group), and also other mature-forest species suffered from fire. Myrmica ruginodis Nylander was able to survive only in less severely burned moist sites, whereas it benefitted from the enhanced light conditions in a non-burned clear-cut. The fire resulted in an essentially ant-free terrain into which pioneering species immigrated. The mortality of nest-founding queens appeared to be high. The results supported the hypothesis that the pioneering species tend to be those that are capable of independent colony founding, followed by species founding nests through temporary nest parasitism. The succession of the burned clear-cut differed from that of the non-burned one, suggesting that habitat selection in immigration and priority effects, i.e. competition, introduce deterministic components in the successional pathways of boreal ant communities.

  • Punttila, ORCID ID:E-mail:
  • Haila, ORCID ID:E-mail:
article id 5566, category Article
Reijo Penttilä, Heikki Kotiranta. (1996). Short-term effects of prescribed burning on wood-rotting fungi. Silva Fennica vol. 30 no. 4 article id 5566. https://doi.org/10.14214/sf.a8501

The prefire fungal flora (polypores and corticoid fungi) of 284 dead trees, mainly fallen trunks of Norway spruce (Picea abies (L.) H. Karst.), was studied in 1991 in an old, spruce-dominated mesic forest in Southern Finland. Species diversity of the prefire fungal flora was very high, including a high proportion of locally rare species and four threatened polypore species in Finland.

In 1992 part of the study area (7.3 ha) was clear-cut and a 1.7 ha forest stand in the centre of study area was left standing with a tree volume of 150 m3/ha, and later on (June 1st) in the same year the whole area was burned. Burning was very efficient and all trees in the forest stand were dead one year after the fire. Also, the ground layer burned almost completely.

In 1993 the fungal flora of the 284 sample trees was studied again. Most of the trees had burned strongly and the fungal species diversity and the evenness in community structure had decreased considerably as compared with the prefire community. Species turnover was also great, especially in corticoid fungi. Greatest losses in the species numbers occurred in moderately and strongly decayed trees, in coniferous trees and in very strongly burned trees. Fungal flora of non-decayed and slightly decayed trees, deciduous trees and slightly burned trees seemed to have survived the fire quite well, and in these groups the species numbers had increased slightly as compared with the prefire community.

Fungal species suffering from fire (anthracophobe species) were mainly growing in moderately and strongly decayed trees before the fire, whereas species favoured by fire (anthracophile species) were growing in less decayed trees. No fruitbodies of threatened polypores or other "old-forest species" of polypores were found again after fire. Some very common and effective wood-rotting fungi (e.g. Fomitopsis pinicola, Fomes fomentarius, Antrodia serialis) survived the fire quite well (anthracoxene species). Species favoured by fire were mainly ruderal species which can utilize new, competition-free resources created by fire, and species that have their optima in dry and open places also outside forest-fire areas. Some rarities, e.g. Phanerochaete raduloides and Physisporinus rivulosus, were favoured by fire.

  • Penttilä, ORCID ID:E-mail:
  • Kotiranta, ORCID ID:E-mail:
article id 5604, category Article
Nigel Dudley, Jean-Paul Jeanrenaud, Adam Markham. (1996). Conservation in boreal forests under conditions of climate change. Silva Fennica vol. 30 no. 2–3 article id 5604. https://doi.org/10.14214/sf.a9249

Addressing the potential impact of climate change on boreal forest ecosystems will require a range of new conservation techniques. During the early 1990s, the scope of WWF's (the World Wide Fund for Nature) forest policy work has broadened from a focus on tropical moist forests to a more general consideration of all the world's forests. Climate change is only one of a series of threats currently facing boreal forests.

Planning conservation strategies that take account of global warming is not easy when there are many computer models of climate change, sometimes predicting very different ecological effects. Climate change could result in some particularly extreme problems for the boreal forest biome. A summary of the problems and opportunities in boreal forests is presented. WWF has also been drawing up strategies for conservation on a global, regional and national level. The organization has concluded that conservation strategies aimed at combatting climate change need not be in direct conflict with other conservation planning requirements. However, proposals have emerged for ways to address the impacts of climate change that would have detrimental impacts on existing conservation plans.

  • Dudley, ORCID ID:E-mail:
  • Jeanrenaud, ORCID ID:E-mail:
  • Markham, ORCID ID:E-mail:
article id 5598, category Article
Timo Kuuluvainen, Kari Leinonen, Markku Nygren, Antti Penttinen. (1996). Statistical opportunities for comparing stand structural heterogeneity in managed and primeval forests: an example from boreal spruce forest in southern Finland. Silva Fennica vol. 30 no. 2–3 article id 5598. https://doi.org/10.14214/sf.a9243

The horizontal and vertical stand structure of living trees was examined in a managed and in a primeval Norway spruce-dominated forest in Southern Finland. Tree size distributions (DBHs, tree height) were compared using frequency histograms. The vertical distribution of tree heights was illustrated as tree height plots and quantified as the tree height diversity (THD) using the Shannon-Weaver formula. The horizontal spatial pattern of trees was described with stem maps and quantified with Ripley's K-function. The spatial autocorrelation of tree sizes was examined with semivariogram analysis. In the managed forest the DBH and height distributions of trees were bimodal, indicating a two-layered vertical structure with a single dominant tree layer and abundant regeneration in the understory. The primeval forest had a much higher total number of trees which were rather evenly distributed in different diameter and tree height classes. The K-function summaries for trees taller than 15 m indicated that the primeval stand was close to complete random pattern. The managed stand was regular at small distances (up to 4 m). The semivariograms of tree sizes (DBH tree height) showed that the managed forest had a clear spatial dependence in tree sizes up to inter-tree distances of about 12 meters. In contrast, the primeval spruce forest had a variance peak at very short inter-tree distances (< 1 m) and only weak spatial autocorrelation at short inter-tree distances (1–5 m). Excluding the understory trees (h < 15 m) from the analysis drastically changed the spatial structure of the forest as revealed by semivariograms. ln general, the structure of the primeval forest was both horizontally and vertically more variable and heterogeneous compared to the managed forest. The applicability of the used methods in describing fine-scale forest structure i discussed.

  • Kuuluvainen, ORCID ID:E-mail:
  • Leinonen, ORCID ID:E-mail:
  • Nygren, ORCID ID:E-mail:
  • Penttinen, ORCID ID:E-mail:
article id 5595, category Article
R.A. Fleming. (1996). A mechanistic perspective of possible influences of climate change on defoliating insects in North America's boreal forests. Silva Fennica vol. 30 no. 2–3 article id 5595. https://doi.org/10.14214/sf.a9240

There is no doubt that tree survival, growth, and reproduction in North America's boreal forests would be directly influenced by the projected changes in climate if they occur. The indirect effects of climate change may be of even greater importance, however, because of their potential for altering the intensity, frequency, and perhaps even the very nature of the disturbance regimes which drive boreal forest dynamics. Insect defoliator populations are one of the dominating disturbance factors in North America's boreal forests and during outbreaks trees are often killed over vast forest areas. If the predicted shifts in climate occur, the damage patterns caused by insects may be considerably changed, particularly those of insects whose temporal and spatial distributions are singularly dependent on climatic factors. The ensuing uncertainties directly affect depletion forecasts, pest hazard rating procedures, and long-term planning for pest control requirements. Because the potential for wildfire often increases in stands after insect attack, uncertainties in future insect damage patterns also lead to uncertainties in fire regimes. In addition, because the rates of processes key to biogeochemical and nutrient recycling are influenced by insect damage, potential changes in damage patterns can indirectly affect ecosystem resilience and the sustainability of the multiple uses of the forest resource.

In this paper, a mechanistic perspective is developed based on available information describing how defoliating forest insects might respond to climate warming. Because of its prevalence and long history of study, the spruce budworm, Choristoneura fumiferana Clem. (Lepidoptera: Tortricidae), is used for illustrative purposes in developing this perspective. The scenarios that follow outline the potential importance of threshold behaviour, historical conditions, phenological relationships, infrequent but extreme weather, complex feedbacks, and natural selection. The urgency of such considerations is emphasized by reference to research suggesting that climate warming may already be influencing some insect lifecycles.

  • Fleming, ORCID ID:E-mail:
article id 5594, category Article
Anssi Niskanen, Tapio Rantala, Olli Saastamoinen. (1996). Economic impacts of carbon sequestration in reforestation: examples from boreal and moist tropical conditions. Silva Fennica vol. 30 no. 2–3 article id 5594. https://doi.org/10.14214/sf.a9239

The impact of carbon sequestration on the financial profitability of four tree plantation cases in Finland and the Philippines were examined. On the basis of stem wood growth; the accumulation of carbon in forest biomass, the formation and decomposition of litter, and the carbon flow in wood-based products were assessed for each reforestation case representing boreal (Finland) and moist tropical conditions (the Philippines). Using different unit values for carbon sequestration the profitability of reforestation was estimated for a fixed 100-year period on a per hectare basis. The financial profitability of reforestation increased notably when the sequestered carbon had high positive values. For example, when the value of carbon sequestration was set to be Twenty-five United States Dollar per megagram of carbon (25 USO/Mg C), the internal rate of return (IRR) of a reforestation investment with Norway spruce (Picea abies (L.) H. Karst.) in Finland increased from 3.2% to 4.1 %. Equally, the IRR of reforestation with mahogany (Swietenia macrophylla King) in the Philippines increased from 12.8% to 15.5%. The present value of carbon sequestration ranged from 39–48% and from 77–101% of the present value of the reforestation cost in Finland and the Philippines, respectively when a 25 USO/Mg C shadow price and a 5% discount rate were applied. Sequestration of one mg of carbon in reforestation in Finland and the Philippines was estimated to cost from 10.5–20.0 and from 4.0–13.6 USO, respectively.

  • Niskanen, ORCID ID:E-mail:
  • Rantala, ORCID ID:E-mail:
  • Saastamoinen, ORCID ID:E-mail:
article id 5588, category Article
Vadim V. Gorshkov, Irene J. Bakkal, Natalie I. Stavrova. (1996). Postfire recovery of forest litter in Scots pine forests in two different regions of boreal zone. Silva Fennica vol. 30 no. 2–3 article id 5588. https://doi.org/10.14214/sf.a9233

Investigations carried out in the Kola peninsula (northern taiga) and in the South-western part of Western Siberia (southern taiga and forest-steppe) revealed identical course of the postfire restoration process of forest litter thickness in Scots pine (Pinus sylvestris L.) forests. Despite the differences in mean annual temperature (2°C) and other climatic characteristics the recovery time for thickness of forest litter in both regions amounts to 90–100 years after fire in pine forests of lichen site type and 120–140 years – in green moss type; the thickness of forest litter therewith corresponds 3–4 cm and 7–8 cm respectively. That mean that within the natural borders of pine forests, communities of a specific type possess uniform characteristics of restoration. On the basis of empirical data, it appears that the predicted increase of mean annual temperature of earth surface by (2°C) will not bring changes into the character of postfire recovery of forest litter thickness. It was shown that during the period of the recovery, which spans about 90 years after fire in pine forests of lichen and green moss-lichen site types and 140 years in ones of green moss site types, the rate of increasing of carbon store in the forest litter averaged 0.6 t ha-1 year-1, 0.1 t ha-1 year-1 and 0.2 t ha-1 year-1, respectively.

  • Gorshkov, ORCID ID:E-mail:
  • Bakkal, ORCID ID:E-mail:
  • Stavrova, ORCID ID:E-mail:
article id 5587, category Article
Dina I. Nazimova, N.P. Polikarpov. (1996). Forest zones of Siberia as determined by climatic zones and their possible transformation trends under global change. Silva Fennica vol. 30 no. 2–3 article id 5587. https://doi.org/10.14214/sf.a9232

A system of zonality in Siberia has been formed under the control of continentality, which provides the heat and humidity regimes of the forest provinces. Three sectors of continentality and four to six boreal sub-zone form a framework for the systematization of the different features of land cover in Siberia. Their climatic ordination provides the fundamental basis for the principal potential forest types (composition, productivity) forecasting the current climate. These are useful in predicting the future transformations and succession under global change.

  • Nazimova, ORCID ID:E-mail:
  • Polikarpov, ORCID ID:E-mail:
article id 5579, category Article
F.G. Hall, P.J. Sellers, D.L. Williams. (1996). Initial results from the boreal ecosystem-atmosphere experiment, BOREAS. Silva Fennica vol. 30 no. 2–3 article id 5579. https://doi.org/10.14214/sf.a9224

BOREAS is a four-year, regional-scale experiment to study the forested continental interior of Canada. It aims at improving our understanding of the interaction between the earths' climate system and the boreal forests at short and intermediate time scales, in order to clarify their role in global change.

During the winter, spring and summer of 1994, five field campaigns were conducted. About 85 investigation teams including nearly 300 scientists participated, including forest ecologists and ecophysiologists, atmospheric physicists, boundary-layer meteorologists, hydrologists, biochemists, atmospheric chemists and remote sensing specialists.

The findings so far have been significant in terms of their implication for global change. The boreal ecosystem, occupying roughly 17 percent of the vegetated land surface and thus an important driver of global weather and climate, absorbs much more solar energy than is assumed by operational numerical weather prediction models. Albedo measurement show that this forest absorbs nearly 91% of the sun's incident energy. Additionally, while it is known that much of the boreal ecosystems consists of forested wetlands, lakes, bogs and fens, the measurements show that the atmosphere above was extremely dry; humidity and deep boundary layer convection (3,000 m) mimicked conditions found only over deserts. Physiological measurements of the trees show that this atmospheric desiccation was a result of the forests' strong biological control limiting surface evaporation. This tight control was linked to the low soil temperature and subsequently reduced rates of photosynthesis. BOREAS measurement also focused on net ecosystem carbon exchange. Data acquired during the late spring and summer, showed the boreal forests to be a net carbon sink. However, no measurements were taken in the early spring following thaw, and in the late fall, where the balance between photosynthesis and respiration is poorly understood. During 1996 additional data will be acquired to resolve the annual carbon budget and how it might depend on interannual climate differences.

  • Hall, ORCID ID:E-mail:
  • Sellers, ORCID ID:E-mail:
  • Williams, ORCID ID:E-mail:
article id 5426, category Article
Juhani Päivänen. (1990). Pohjoisen havumetsävyöhykkeen suot ja niiden metsätaloudellinen hyväksikäyttö. Silva Fennica vol. 24 no. 2 article id 5426. https://doi.org/10.14214/sf.a15580
English title: Peatlands of the boreal zone and their utilization in forestry.

The paper is a review on utilization of peatlands in forestry in the countries of boreal zone: Finland, Norway, Sweden, Canada, the United States and the Soviet Union. First, the concept of peatlands, the types of peatlands throughout the zone are defined, and the use of natural peatlands is described. Finally, the drainage of peatlands for forestry purposes in the countries is reviewed. According to the statistics, a total of 13 million ha of peatlands have been drained in Fennoscandia and the Soviet Union.

  • Päivänen, ORCID ID:E-mail:
article id 5362, category Article
Seppo Kellomäki, Heikki Hänninen, Taneli Kolström. (1988). Model computations on the impacts of the climatic change on the productivity and silvicultural management of the forest ecosystem. Silva Fennica vol. 22 no. 4 article id 5362. https://doi.org/10.14214/sf.a15519

The model computations indicate that the climatic change in the form of higher temperatures and more precipitation could increase the productivity of the forest ecosystem and lead to higher rates of regeneration and growth. More frequent and intensive thinnings are needed to avoid the mortality of trees induced by accelerated maturation and attacks of fungi and insects. The climatic change could support the dominance of deciduous tree species and necessitate an intensification of the tending of seedling stands of conifers. The rise of air temperature during autumn and winter could change also the annual growth rhythm of trees and result in dehardening and subsequent frost damages and attacks of insects and fungi. The pest management could be the greatest challenge to the future silviculture, which could be modified most in Northern Finland.

The PDF includes an abstract in Finnish.

  • Kellomäki, ORCID ID:E-mail:
  • Hänninen, ORCID ID:E-mail:
  • Kolström, ORCID ID:E-mail:
article id 5345, category Article
Leo Koutaniemi, Raimo Koponen, Kyösti Rajanen. (1988). Podzolization as studied from terraces of various ages in two river valleys, Northern Finland. Silva Fennica vol. 22 no. 2 article id 5345. https://doi.org/10.14214/sf.a15502

The study was made in the Ivalojoki and Oulankajoki valleys, consisting of terraces of well sorted sandy material aged 9500–300 B.P. The vegetation is characterized by dry and moderately dry forest types with Scots pine (Pinus sylvestris L.) as the dominant tree species. The study included: forest types, particle size and sorting of mineral horizons, thickness of horizons, amount of organic material, pH, electrical conductivity, and NH4OAc (pH 4.56) extractable Fe, Al, P, K, Mg, Mn and Zn concentrations. The principal aim was to study the interrelationships between all these properties with special reference to the age of the soil.

The results allowed a distinction to be made between the following categories: (1) features typical of podsolization (e.g. increase in leaching of Fe and Al with age of soil from the A2), (2) certain factors showing higher values in the north (Ivalo) than in the south (Oulanka), principally Fe and Mg, (3) declining trends in P, Mg, Mn and Zn concentrations with age, which may partly be due to the geological history, and (4) declining trends in amount of organic material and electrical conductivity with age, these both being factors arising from the geological history rather than from podzolization.

The PDF includes a summary in Finnish.

  • Koutaniemi, ORCID ID:E-mail:
  • Koponen, ORCID ID:E-mail:
  • Rajanen, ORCID ID:E-mail:
article id 5318, category Article
Tapio Lindholm, Harri Vasander. (1987). Vegetation and stand development of mesic forest after prescribed burning. Silva Fennica vol. 21 no. 3 article id 5318. https://doi.org/10.14214/sf.a15475

This study deals with the succession of vegetation and tree stand in 16 mesic Myrtillus site type Scots pine (Pinus sylvestris L.) plantations after prescribed burning in Evo, Southern Finland. The oldest tree stands studied were about 30-year-old. The growth of trees followed the height index of Myrtillus type. The vegetation was first mesic, dominated by grasses and herbs, turning more xeric after four years. This change was accelerated by treatment with herbicides. After the closure of tree stand, vegetation became more characteristic of forest vegetation, but pioneer species and composition disappeared slowly. The basic characters of vegetation succession could be clearly described by DCA ordination and TWINSPAN classification. The study confirmed that Myrtillus type has succession phases which are typical for each age phases as Cajander’s forest site type theory has proposed. However, differences in primary and secondary site factors have their own effects on the vegetation of the succession phases.

The PDF includes an abstract in Finnish.

  • Lindholm, ORCID ID:E-mail:
  • Vasander, ORCID ID:E-mail:
article id 7056, category Article
Väinö Auer. (1921). Zur Kenntnis der Stratigraphie der mittelöstenbottnischen Moore. Acta Forestalia Fennica vol. 18 no. 4 article id 7056. https://doi.org/10.14214/aff.7056
English title: About stratification of peatlands in middle Ostrobothnia.

The article describes the characteristics and emergence and development of four peatlands in middle Ostrobothnia, Finland. In addition, the age of the Rahkaneva and Kurmunneva peatlands was determined and their relationship. The different layers of the peat and the plant relics they contain are represented.

The age determination was based on different layers of the peat that contain different fossils of pollen and pieces of different plant species. The height of the layers was measured. It seems that Rahkaneva has grown into its current area during a warm and dry period in Subboreal. 

  • Auer, ORCID ID:E-mail:
article id 7056, category Article
Väinö Auer. (1921). Zur Kenntnis der Stratigraphie der mittelöstenbottnischen Moore. Acta Forestalia Fennica vol. 18 no. 4 article id 7056. https://doi.org/10.14214/aff.7056
English title: About stratification of peatlands in middle Ostrobothnia.

The article describes the characteristics and emergence and development of four peatlands in middle Ostrobothnia, Finland. In addition, the age of the Rahkaneva and Kurmunneva peatlands was determined and their relationship. The different layers of the peat and the plant relics they contain are represented.

The age determination was based on different layers of the peat that contain different fossils of pollen and pieces of different plant species. The height of the layers was measured. It seems that Rahkaneva has grown into its current area during a warm and dry period in Subboreal. 

  • Auer, ORCID ID:E-mail:
article id 5216, category Article
Anna-Maija Hallaksela. (1984). Causal agents of butt-rot in Norway spruce in southern Finland. Silva Fennica vol. 18 no. 3 article id 5216. https://doi.org/10.14214/sf.a15395

A total of 146 Norway spruce-dominated clear-cutting areas and 140 of the sample plots included in the 7th National Forest Inventory in Finland were examined during 1974–78. The micro-organisms causing decay in Norway spruce (Picea abies (L.) H. Karst.) sample trees were identified. The most common causal agent of butt-rot was Heterbasidion annosum (Fr.) Bref. Other fungi causing decay in the spruce trees were Armillaria mellea (Vahl.) Quél, Stereum sanguinolentum (Alb. & Schw. ex Fr.), Resinicum bicolor (Alb. & Schw. ex Fr.) Parm. and Climacocystis borealis (Fr.) Kotl. & Pouz. Species of Ascocoryne were very often present in the decay. The decay caused by H. annosum was considerably more extensive than cases of decay where the fungus was not present.

The PDF includes a summary in Finnish.

  • Hallaksela, ORCID ID:E-mail:
article id 7506, category Article
Eero Kubin, Lauri Kemppainen. (1994). Effect of soil preparation of boreal spruce forest on air and soil temperature conditions in forest regeneration areas. Acta Forestalia Fennica no. 244 article id 7506. https://doi.org/10.14214/aff.7506

The effect of scarification, ploughing and cross-directional ploughing on temperature conditions in the soil and adjacent air layer have been studied during 11 growth periods by using an unprepared clear-cut area as a control site. The development of seedling stand was followed to determine its shading effect on the soil surface.

Soil preparation decreased the daily temperature amplitude of the air at the height of 10 cm. The maximum temperatures on sunny days were lower in the tilts of the ploughed and in the humps of the cross-directional ploughed sites compared with the unprepared area. Correspondingly, the night temperatures were higher and so the soil preparation reduced the risk of night frost. In the soil at the depth of 5 cm, soil preparation increased daytime temperatures and reduced night temperatures compared with unprepared area. The maximum increase in monthly mean temperatures was almost 5°C, and the daily variation in the surface parts of the tilts and humps increased so that excessively high temperatures for the optimal growth of the root systems were measured from time to time. The temperature also rose at the depths of 50 and 100 cm.

Soil preparation also increased the cumulative temperature sum. The highest sums accumulated during the summer months were recorded at the depth of 5 cm in the humps of cross-directional ploughed area (1,127 dd.) and in the tilts of the ploughed area (1,106 dd.), while the corresponding figure in the unprepared soil was 718 dd. At the height of 10 cm the highest temperature sum was 1,020 dd. in the hump, and 925 dd. in the unprepared area.

The incidence of high temperature amplitudes and frequency of high temperatures at the depth of 5 cm decreased most rapidly in the humps of cross-sectional ploughed area and the ploughing tilts towards the end of the study period. The decrease was attributed principally to the compressing of tilts, the ground vegetation succession and the growth of seedlings. The difference between the prepared and unprepared area did not diminish. The increase in temperature due to soil preparation, thus, lasted at least over 10 years.

  • Kubin, ORCID ID:E-mail:
  • Kemppainen, ORCID ID:E-mail:
article id 7671, category Article
Eero Kubin, Lauri Kemppainen. (1991). Effect of clearcutting of boreal spruce forest on air and soil temperature conditions. Acta Forestalia Fennica no. 225 article id 7671. https://doi.org/10.14214/aff.7671

The present paper deals with the effects of clearcutting on soil and air temperature and the development of temperature conditions during the 12 growing seasons following clearcutting of a Norway spruce (Picea abies (L.) H. Karst.) stand on a Vaccinium-Myrtillus forest type in Kainuu, northeast Finland. The uncut control site had a growing stock of 140 m3/ha. The temperature measurements were carried out by means of thermographs, Grant measuring devices and minimum and maximum glass thermometers.

Clearcutting had no significant influence on temperatures measures at 2 m above the ground in a meteorological screen and no changes occurred in them during the period studied, while on the ground level and in the adjacent layer of air the daily maxima increased and the daily minima decreased as compared with uncut forest. The greatest difference was over 10°C between the maximum temperatures at 10 cm and almost 8°C between the minimum temperatures. Night frosts were considerably more common at 10 cm above the ground in the clearcut area than in uncut forests.

Temperature differences were smaller in the soil than close to ground level. Day temperatures were 2–3°C higher in the clearcut area than in uncut forests, and differences between night temperatures at this depth were even smaller. Correspondingly, temperatures were 3–5°C higher at depths of 50 cm and 100 cm in the clearcut area during the whole measuring period. The differences between the temperatures in the clearcut area and uncut forests did not diminish to any significant extent during the 12 years despite the stocking of the former area with seedlings.

The PDF includes a summary in Finnish.

  • Kubin, ORCID ID:E-mail:
  • Kemppainen, ORCID ID:E-mail:
article id 7606, category Article
Kari Heliövaara, Rauno Väisänen, Auli Immonen. (1991). Quantitative biogeography of the bark beetles (Coleoptera, Scolytidae) in northern Europe. Acta Forestalia Fennica no. 219 article id 7606. https://doi.org/10.14214/aff.7606

Biogeographical patterns of the Scolytidae in Fennoscandia and Denmark, based on species incidence data from the approximately 70 km x 70 km quadrats (n = 221) used by Lekander et al. (1977), were classified to environmental variables using multivariate methods (two-way indicator species analysis, detrended correspondence analysis, canonical correspondence analysis).

The distributional patterns of scolytid species composition showed similar features to earlier presented zonations based on vegetation composition. One major difference, however, was that the region was more clearly divided in an east-west direction. Temperature variables associated with the location of the quadrat had the highest canonical coefficient values on the first axis of the CCA. Although these variables were the most important determinants of the biogeographical variation in the beetle species assemblages, annual precipitation and the distribution of Picea abies also improved the fit of the species data.

Samples with the most deviant rarity and typicality indices for the scolytid species assempblages in each quadrat were concentrated in several southern Scandinavian quadrats, in some quadrats in northern Sweden, and especially on the Swedish islands (Öland, Gotland, Gotska Sandön) in the Baltic Sea. The use of rarity indices which do not take the number of species per quadrat, also resulted high values for areas near Stockholm and Helsinki with well-known faunas. Methodological tests in which the real changes in the distribution of Ips acuminatus and I. amitinus were used as indicators showed that the currently available multivariate methods are sensitive to small faunal shifts even, and thus permit analysis of the fauna in relation to environmental changes. However, this requires more detailed monitoring of the species’ distributions over longer time spans.

Distribution of seven species (Scolytus intricatus, S. laevis, Hylurgops glabratus, Crypturgus cinereus, Pityogenes salasi, Ips typographus, and Cyleborus dispar) were predicted by logistic regression models using climatic variables. In spite of the deficiencies in the data and the environmental variables selected, the models were relatively good for several but not for all species. The potential effects of climate change on bark beetles are discussed.

The PDF includes a summary in Finnish.

  • Heliövaara, ORCID ID:E-mail:
  • Väisänen, ORCID ID:E-mail:
  • Immonen, ORCID ID:E-mail:
article id 7636, category Article
Kari Heliövaara, Rauno Väisänen. (1984). Effects of modern forestry on Northwestern European forest invertebrates: a synthesis. Acta Forestalia Fennica no. 189 article id 7636. https://doi.org/10.14214/aff.7636

The effects of modern forestry on northwest European forest invertebrates are summarized and analysed mainly on the basis of published literature. The direct influence of different practices including clear-cutting, thinning, burning-over, ploughing, changes in tree species composition of stands, fertilization, insecticides, pheromones and biological control are discussed from a forest zoological point of view. Also, the indirect effects of general changes in boreal forest dynamics, loss of primeval forests, cessation of natural fires and the dominance of young stands are described. The direct effects of different silvicultural practices on the species composition and diversity of forest invertebrates are usually considered to be striking but transient. However, when large areas are treated, the species associated with primeval forests, especially with the wood composition system in them, as well as the species associated with fires, seem to have drastically declined. In northwest Europe, efficient forestry has not caused such serious pest problems as is known from tropical countries or North America.

The PDF includes a summary in Finnish.

  • Heliövaara, ORCID ID:E-mail:
  • Väisänen, ORCID ID:E-mail:

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