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Silva Fennica vol. 54 | 2020

Category: Editorial

article id 10452, category Editorial
Matti Maltamo. (2020). Re-searching the forests. Silva Fennica vol. 54 no. 4 article id 10452. https://doi.org/10.14214/sf.10452
  • Maltamo, University of Eastern Finland, School of Forest Sciences, Joensuu, Finland ORCID ID:E-mail: matti.maltamo@uef.fi (email)
article id 10411, category Editorial
Pekka Nygren. (2020). Improvement of reproducibility and research transparency in Silva Fennica. Silva Fennica vol. 54 no. 3 article id 10411. https://doi.org/10.14214/sf.10411
  • Nygren, Finnish Society of Forest Science, Viikinkaari 6, FI-00790 Helsinki, Finland ORCID ID:E-mail: pekka.nygren@metsatiede.org (email)
article id 10362, category Editorial
Svetlana Saarela. (2020). On being a female supervisor in forest research education. Silva Fennica vol. 54 no. 2 article id 10362. https://doi.org/10.14214/sf.10362
  • Saarela, Department of Forest Resource Management, Swedish University of Agricultural Sciences, Box 7044, SE-750 07 Uppsala, Sweden ORCID ID: https://orcid.org/0000-0002-9044-7249 E-mail: svetlana.saarela@slu.se (email)
article id 10333, category Editorial
Matti Maltamo. (2020). Change of the Subject Editor in Silva Fennica. Silva Fennica vol. 54 no. 1 article id 10333. https://doi.org/10.14214/sf.10333
  • Maltamo, University of Eastern Finland, School of Forest Sciences, Joensuu, Finland ORCID ID:E-mail: matti.maltamo@uef.fi (email)
article id 10329, category Editorial
Lars Eliasson. (2020). Forest research and the needs of our stakeholders. Silva Fennica vol. 54 no. 1 article id 10329. https://doi.org/10.14214/sf.10329
  • Eliasson, Skogforsk, The Forestry Research Institute of Sweden, Uppsala Science Park, 751 83 Uppsala, Sweden ORCID ID: https://orcid.org/0000-0002-2038-9864 E-mail: lars.eliasson@skogforsk.se (email)

Category: Research article

article id 10351, category Research article
Karol Bronisz, Michał Zasada. (2020). Taper models for black locust in west Poland. Silva Fennica vol. 54 no. 5 article id 10351. https://doi.org/10.14214/sf.10351
Highlights: Seven taper models with different numbers of estimated parameters were analysed; Section diameter and volume was modelled using fixed and mixed-effects modelling approaches; The variable-form taper model with eight estimated parameters fitted the data the best; The lowest error for volume prediction was achieved for the fixed-effects taper model.

The diameter at any point on a stem and tree volume are some of the most important types of information used in forest management planning. One of the methods to predict the diameter at any point on a stem is to develop taper models. Black locust (Robinia pseudoacacia L.) occurs in almost all forests in Poland, with the largest concentration in the western part of the country. Using empirical data obtained from 13 black locust stands (48 felled trees), seven taper models with different numbers of estimated parameters were analysed for section diameters both over and under bark using fixed and mixed-effects modelling approaches. Assuming a lack of additional measurements, the best fitted taper models were used for the prediction of over bark volume using both methods. The predicted volume was compared with the results from different volume equations available for black locust. The variable-form taper model with eight estimated parameters fitted the data the best. The lowest root mean square error for volume prediction was achieved for the elaborated fixed-effects taper model (0.0476), followed by the mixed-effects taper model (0.0489). At the same time, the difference between the volume relative errors achieved based on the taper models does not differ significantly from the results obtained using the volume equations already available for black locust (two of the three analysed).

  • Bronisz, Institute of Forest Sciences, Warsaw University of Life Sciences-SGGW, Nowoursynowska 159, PL 02-776 Warsaw, Poland ORCID ID:E-mail: karol.bronisz@wl.sggw.pl (email)
  • Zasada, Institute of Forest Sciences, Warsaw University of Life Sciences-SGGW, Nowoursynowska 159, PL 02-776 Warsaw, Poland ORCID ID: https://orcid.org/0000-0002-4881-296X E-mail: Michal.Zasada@wl.sggw.pl
article id 10392, category Research article
Paula Jylhä, Pasi Rikkonen, Katri Hamunen. (2020). Size matters – an analysis of business models and the financial performance of Finnish wood-harvesting companies. Silva Fennica vol. 54 no. 4 article id 10392. https://doi.org/10.14214/sf.10392
Highlights: Economic success was related to company’s size, Small companies with a turnover of less than 600 000 € a–1 are struggling with profitability; Large enterprises continue to grow and innovate new business concepts; The competitive edge of large companies was reflected in large production capacity, efficient operations, versatile supply of services, and power in negotiations.

The size of Finnish wood harvesting enterprises has grown, and entrepreneurs have become responsible for various additional tasks, resulting in networking with other harvesting enterprises of various sizes and suppliers of supporting services, but the profitability of the wood harvesting sector has remained low. In the present study, the financial performance of 83 wood harvesting companies in Eastern and Northern Finland was evaluated, based on public final account data from a five-year period between 2013 and 2017. The factors underlying economic success were identified based on 19 semi-structured entrepreneur interviews. The Business Model Canvas framework was applied in the analyses. In particular, the smallest companies (with an annual turnover of less than 600 000 €) struggled with profitability. They showed increasing indebtedness, suffered from poor power in negotiations, had typically short-term contracts, and faced difficulties in retaining skilled operators. Most of the small companies were subcontractors of larger wood-harvesting companies. The better economic success of larger companies was likely based on their capacity to provide wood harvesting services in large volumes and supply versatile services, power in negotiations, and more cost-effective operations. The future development of wood harvesting seems to be polarised: larger enterprises are likely to continue growing, while the size of smaller enterprises has stabilised. Enhancing business management skills and practices is required in enterprises of all size groups.

  • Jylhä, Natural Resources Institute Finland (Luke), Production systems, Teknologiakatu 7, FI-67100 Kokkola, Finland ORCID ID:E-mail: paula.jylha@luke.fi (email)
  • Rikkonen, Natural Resources Institute Finland (Luke), Bioeconomy and environment, Lönnrotinkatu 7, FI-50100 Mikkeli, Finland ORCID ID:E-mail: pasi.rikkonen@luke.fi
  • Hamunen, Natural Resources Institute Finland (Luke), Bioeconomy and environment, Yliopistokatu 6B, FI-80100 Joensuu, Finland ORCID ID:E-mail: katri.hamunen@luke.fi
article id 10385, category Research article
Perttu Anttila, Tuomas Nummelin, Kari Väätäinen, Juha Laitila. (2020). The effect of winter weather on timber truck tare weights. Silva Fennica vol. 54 no. 4 article id 10385. https://doi.org/10.14214/sf.10385
Highlights: In a one-year follow-up study of eight timber trucks in Finland, up to 6–12% increase in tare weights was observed in wintertime; Compared with summertime tare weights, the maximum increase varied between 1560 kg and 3100 kg; Potential payload loss was explained by temperature, relative humidity and precipitation.

In wintertime, the payload capacity of a timber truck is reduced by snow that accumulates on the structures of the truck. The aim of this study was to quantify the potential payload loss due to snow and winter accessories and to predict the loss with weather variables. Tare weights of eight timber trucks were collected at mill receptions in Finland over a one-year period. Monthly and annual loss of potential payload was estimated using the tare measurements in summer months as a reference. Each load was also connected with weather data at the location and time of delivery and payload loss explained by the weather data with the aid of regression models. The maximum loss of payload varied between 1560 kg and 3100 kg. On a monthly basis, the highest losses occurred in January, when the median values varied between 760 kg and 2180 kg. Over the year, the payload loss ranged between the trucks from 0.5% to 1.5% (from 1.9% and 5.1% in January) of the total number of loads in the study. Payload loss was found to increase with decreasing temperature, increasing relative humidity and increasing precipitation. Although the average payload loss was not very high, the biggest losses occur just during the season of highest capacity utilization. Big differences were also found in the tare weights between the trucks. The results of the study give incentive to develop truck and trailer structures that reduce the adherence of snow.

  • Anttila, Natural Resources Institute Finland (Luke), Latokartanonkaari 9, FI-00790 Helsinki, Finland ORCID ID: https://orcid.org/0000-0002-6131-392X E-mail: perttu.anttila@luke.fi (email)
  • Nummelin, Natural Resources Institute Finland (Luke), Latokartanonkaari 9, FI-00790 Helsinki, Finland ORCID ID:E-mail: tuomas.nummelin@luke.fi
  • Väätäinen, Natural Resources Institute Finland (Luke), Yliopistokatu 6, FI-80100 Joensuu, Finland ORCID ID:E-mail: kari.vaatainen@luke.fi
  • Laitila, Natural Resources Institute Finland (Luke), Yliopistokatu 6, FI-80100 Joensuu, Finland ORCID ID: https://orcid.org/0000-0003-4431-3319 E-mail: juha.laitila@luke.fi
article id 10375, category Research article
Amy Wotherspoon, Nelson Thiffault, Robert L. Bradley. (2020). Resource availability and physiological response of black spruce to scarification in two climatic regions of Québec (Canada). Silva Fennica vol. 54 no. 4 article id 10375. https://doi.org/10.14214/sf.10375
Highlights: Mechanical scarification of clearcut sites in two climatic regions maintained high growth rates of regenerating black spruce 18 years after treatment; In both regions, scarification reduced soil moisture and increased water use efficiency; In the cooler-humid region, scarification improved soil nitrogen mineralization.

Scarification is a mechanical site preparation technique designed to create microsites that will favor the growth of planted tree seedlings after clearcutting. However, the positive growth response of black spruce (Picea mariana (Mill.) Britton, Sterns & Poggenb.) to scarification varies across different sites. We hypothesized that this was due to different forms of physiological stress induced by different climates or by the severity of competition from ericaceous shrubs. We thus compared the effects of scarification on black spruce needle gas exchange and other foliar properties, as well as on indices of soil water and nitrogen availability, in relatively warm-dry (Abitibi) vs. cool-humid (Côte-Nord) climates in the province of Québec (Canada). We found a similar positive effect of scarification on tree height in Abitibi and Côte-Nord. Scarification reduced soil moisture in both climatic regions, but increased soil N mineralization in Côte-Nord only. Accordingly, scarification increased the instantaneous water use efficiency in both climate regions, but decreased photosynthetic N use efficiency in Côte-Nord only. In both regions, we found a positive relationship between foliar δ18O and δ13C on scarified plots, providing further evidence that increased growth due to scarification depends on a decrease in stomatal conductance. We conclude that scarification increases total evapotranspiration of trees evenly across the east-to-west moisture gradient in the province of Québec, but also improves long-term soil nutritional quality in a cooler-humid climate.

  • Wotherspoon, Département de biologie, Université de Sherbrooke, Sherbrooke, Québec, J1K 2R1, Canada ORCID ID:E-mail: amy.wotherspoon@usherbrooke.ca (email)
  • Thiffault, Canadian Wood Fibre Centre, Canadian Forest Service, Natural Resources Canada, 1055 du. P.E.P.S., P.O. Box 10380, Québec, G1V 4C7, Canada ORCID ID:E-mail: nelson.thiffault@canada.ca
  • Bradley, Département de biologie, Université de Sherbrooke, Sherbrooke, Québec, J1K 2R1, Canada ORCID ID:E-mail: robert.bradley@usherbrooke.ca
article id 10370, category Research article
Juha Lappi, Timo Pukkala. (2020). Analyzing ingrowth using zero-inflated negative binomial models. Silva Fennica vol. 54 no. 4 article id 10370. https://doi.org/10.14214/sf.10370
Highlights: Models were developed to describe ingrowth in national forest inventory data; The data were more dispersed than Poisson data and included many zeros; Fixed-effects models had larger zero-inflation probability and overdispersion parameter than mixed-effect models; Mixed-effects models had larger likelihood than fixed-effects models but provided biased predictions; Prediction of right-censored ingrowth may be useful owing to large overdispersion.

Ingrowth is an important element of stand dynamics in several silvicultural systems, especially in continuous cover forestry. Earlier predictive models for ingrowth in Finnish forests are few and not based on up-to-date statistical methods. Ingrowth is here defined as the number of trees over 1.3 m entering a plot. This study developed new ingrowth models for Scots pine (Pinus sylvestris L.), Norway spruce (Picea abies (L.) H. Karst.) and birch (Betula pendula Roth and B. pubescens Ehrh.) using data from the permanent sample plots of the Finnish national forest inventory. The data were over-dispersed compared to a Poisson process and had many zeros. Therefore, a zero-inflated negative binomial model was used. The total and species-specific stand basal areas, temperature sum and fertility class were used as predictors in the ingrowth models. Both fixed-effects and mixed-effects models were fitted. The mixed-effects model versions included random plot effects. The mixed-effects models had larger likelihoods but provided biased predictions. Also censored prediction was considered where only a certain maximum number of ingrowth trees were accepted for a plot. The models predicted most pine ingrowth in pine-dominated stands on sub-xeric and xeric sites where stand basal area was low. The predicted amount of spruce ingrowth was maximized when the basal area of spruce was 13 m2 ha–1. Increasing temperature sum increased spruce ingrowth. Predicted birch ingrowth decreased with increasing stand basal area and towards low fertility classes. An admixture of pine increased the predicted amount of spruce ingrowth.

  • Lappi, University of Eastern Finland, P.O. Box 111, FI-80101 Joensuu, Finland ORCID ID:E-mail: juha.lappi.sjk@gmail.com (email)
  • Pukkala, University of Eastern Finland, P.O. Box 111, FI-80101 Joensuu, Finland ORCID ID:E-mail: timo.pukkala@uef.fi
article id 10347, category Research article
Matti Katila, Tuomas Rajala, Annika Kangas. (2020). Assessing local trends in indicators of ecosystem services with a time series of forest resource maps. Silva Fennica vol. 54 no. 4 article id 10347. https://doi.org/10.14214/sf.10347
Highlights: Untitled Document Contextual Mann-Kendall test detects significant trends in time-series of forest maps; Trends become more consistent as the areal unit size used for test input increases; Changes in different scales reflect different phenomena in forests; Significant trends were detected even after multiple testing correction.

Since the 1990’s, forest resource maps and small area estimates have been produced by combining national forest inventory (NFI) field plot data, optical satellite images and numerical map data using a non-parametric k-nearest neighbour method. In Finland, thematic maps of forest variables have been produced by the means of multi-source NFI (MS-NFI) for eight to ten times depending on the geographical area, but the resulting time series have not been systematically utilized. The objective of this study was to explore the possibilities of the time series for monitoring the key ecosystem condition indicators for forests. To this end, a contextual Mann-Kendall (CMK) test was applied to detect trends in time-series of two decades of thematic maps. The usefulness of the observed trends may depend both on the scale of the phenomena themselves and the uncertainties involved in the maps. Thus, several spatial scales were tested: the MS-NFI maps at 16 × 16 m2 pixel size and units of 240 × 240 m2, 1200 × 1200 m2 and 12  000 × 12  000 m2 aggregated from the MS-NFI map data. The CMK test detected areas of significant increasing trends of mean volume on both study sites and at various unit sizes except for the original thematic map pixel size. For other variables such as the mean volume of tree species groups, the proportion of broadleaved tree species and the stand age, significant trends were mostly found only for the largest unit size, 12  000 × 12  000 m2. The multiple testing corrections decreased the amount of significant p-values from the CMK test strongly. The study showed that significant trends can be detected enabling indicators of ecosystem services to be monitored from a time-series of satellite image-based thematic forest maps.

  • Katila, Natural Resources Institute Finland (Luke), Bioeconomy and environment, Latokartanonkaari 9, FI-00790 Helsinki, Finland; ORCID ID: https://orcid.org/0000-0001-6946-5736 E-mail: matti.katila@luke.fi (email)
  • Rajala, Natural Resources Institute Finland (Luke), Natural resources, Latokartanonkaari 9, FI-00790 Helsinki, Finland ORCID ID:E-mail: tuomas.rajala@luke.fi
  • Kangas, Natural Resources Institute Finland (Luke), Bioeconomy and environment, Yliopistokatu 6, FI-80100 Joensuu, Finland ORCID ID: https://orcid.org/0000-0002-8637-5668 E-mail: annika.kangas@luke.fi
article id 10331, category Research article
Jussi Juola, Aarne Hovi, Miina Rautiainen. (2020). Multiangular spectra of tree bark for common boreal tree species in Europe. Silva Fennica vol. 54 no. 4 article id 10331. https://doi.org/10.14214/sf.10331
Highlights: Novel multiangular measurement set-up for hyperspectral imaging; Multiangular spectra of silver birch (Betula pendula), Scots pine (Pinus sylvestris) and Norway spruce (Picea abies) stem bark samples were collected; Intra- and interspecific variations in reflectance were analyzed; Demonstration of tree species identification based on stem bark spectra; Collected spectra openly available in SPECCHIO Spectral Information System.

Despite the importance of spectral properties of woody tree structures, they are seldom represented in research related to forests, remote sensing, and reflectance modeling. This study presents a novel imaging multiangular measurement set-up that utilizes a mobile handheld hyperspectral camera (Specim IQ, 400–1000 nm), and can measure stem bark spectra in a controlled laboratory setting. We measured multiangular reflectance spectra of silver birch (Betula pendula Roth), Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) Karst.) stem bark, and demonstrated the potential of using bark spectra in identifying tree species using a Support Vector Machine (SVM) based approach. Intraspecific reflectance variability was the lowest in visible (400–700 nm), and the highest in near-infrared (700–1000 nm) wavelength regions. Interspecific variation was the largest in the red, red-edge and near-infrared spectral bands. Spatial variation of reflectance along the tree height and different sides of the stem (north and south) were found. Both birch and pine had increased reflectance in the forward-scattering directions for visible to near-infrared wavelength regions, whilst spruce displayed the same only for the visible wavelength region. In addition, spruce had increased reflectance in the backward-scattering directions. In spite of the intraspecific variations, SVM could identify tree species with 88.8% overall accuracy when using pixel-specific spectra, and with 97.2% overall accuracy when using mean spectra per image. Based on our results it is possible to identify common boreal tree species based on their stem bark spectra using images from mobile hyperspectral cameras.

  • Juola, Aalto University, School of Engineering, Department of Built Environment, P.O. Box 14100, FI-00760 Aalto, Finland ORCID ID: https://orcid.org/0000-0002-6050-7247 E-mail: jussi.juola@aalto.fi (email)
  • Hovi, Aalto University, School of Engineering, Department of Built Environment, P.O. Box 14100, FI-00760 Aalto, Finland ORCID ID: https://orcid.org/0000-0002-4384-5279 E-mail: aarne.hovi@aalto.fi
  • Rautiainen, Aalto University, School of Engineering, Department of Built Environment, P.O. Box 14100, FI-00760 Aalto, Finland; Aalto University, School of Electrical Engineering, Department of Electronics and Nanoengineering, P.O. Box 15500, FI-00760 Aalto, Finland ORCID ID: https://orcid.org/0000-0002-6568-3258 E-mail: miina.a.rautiainen@aalto.fi
article id 10276, category Research article
Adas Marčiulynas, Vaida Sirgedaitė-Šėžienė, Povilas Žemaitis, Āris Jansons, Virgilijus Baliuckas. (2020). Resistance of Scots pine half-sib families to Heterobasidion annosum in progeny field trials. Silva Fennica vol. 54 no. 4 article id 10276. https://doi.org/10.14214/sf.10276
Highlights: Large genetic variation was estimated in the resistance of Scots pine half-sib families to root rot in field trials; A strong relationship was observed between family resistance to root rot and phenolic compound concentration in the wood.

Five Scots pine (Pinus sylvestris L.) progeny field trials, each established in different Lithuanian regions of provenance in 1983, were studied. Each progeny field trial consists of 140 half-sib families from seven populations (20 families from each population). The evaluation was carried out in 2012 and 2018 to assess the families resistance to Heterobasidion annosum (Fr.) Bref. An index of resistance in the infected plots was calculated. To verify the accuracy of the method, total phenolic compounds (TPC) was chosen as key parameter to compare with the plant resistance index. During the six years between the two assessments, the percentage of living Scots pine trees in the progeny field trials decreased up to 20 percentage points (range: 4 p.p. to 20 p.p.). In 2018 the area of H. annosum damaged plots (in percentage from total field trial area) varied from 17 to 27%. Tree mortality in the trial correlates with site soil fertility – more fertile soils were distinguished by higher tree percentage loss and vice versa. Using analysis from combined data of all progeny trials, the family variance component reached 13.3 ± 2.2% and family heritability was 0.81. Family heritability estimates for root rot resistance show possibilities of high breeding effectiveness. The correlations between the trials in family resistance estimates were negligible (ranging from 0 to 0.28). The significant high correlation coefficient was determined between the resistance index and TPC concentration (r = 0.77, p = 0.0003). This allows us to assume that plant resistance is directly linked on TPC synthesis. The results indicate that the chosen methods of chemical resistance for identification of root rot-resistant genotypes are applicable for the selection of Scots pine half-sib families in the field trials with higher resistance to pathogens.

  • Marčiulynas, Institute of Forestry, Lithuanian Research Centre for Agriculture and Forestry, Liepų str. 1, LT-53101 Girionys, Kaunas District, Lithuania ORCID ID:E-mail: adas.marciulynas@mi.lt (email)
  • Sirgedaitė-Šėžienė, Institute of Forestry, Lithuanian Research Centre for Agriculture and Forestry, Liepų str. 1, LT-53101 Girionys, Kaunas District, Lithuania ORCID ID:E-mail: vaida.seziene@mi.lt
  • Žemaitis, Institute of Forestry, Lithuanian Research Centre for Agriculture and Forestry, Liepų str. 1, LT-53101 Girionys, Kaunas District, Lithuania ORCID ID:E-mail: povilas.zemaitis@mi.lt
  • Jansons, Latvian State Forest Research Institute “Silava”, Department of Forest Tree Breeding, Rigas St.t. 111, Salaspils LV-2169, Latvia ORCID ID:E-mail: aris.jansons@silava.lv
  • Baliuckas, Institute of Forestry, Lithuanian Research Centre for Agriculture and Forestry, Liepų str. 1, LT-53101 Girionys, Kaunas District, Lithuania ORCID ID:E-mail: virgilijus.baliuckas@mi.lt
article id 10269, category Research article
Annika Kangas, Helena M. Henttonen, Timo P. Pitkänen, Sakari Sarkkola, Juha Heikkinen. (2020). Re-calibrating stem volume models – is there change in the tree trunk form from the 1970s to the 2010s in Finland? Silva Fennica vol. 54 no. 4 article id 10269. https://doi.org/10.14214/sf.10269
Highlights: TLS data showed that trunk form has changed in Finland from the 1970s; Significant differences were observed for all tree species; The trees in TLS data are on average more slender than in the old data.

The tree stem volume models of Norway spruce, Scots pine and silver and downy birch currently used in Finland are based on data collected during 1968–1972. These models include four different formulations of a volume model, with three different combinations of independent variables: 1) diameter at height of 1.3 m above ground (dbh), 2) dbh and tree height (h) and 3) dbh, h and upper diameter at height of 6 m (d6). In recent National Forest Inventories of Finland, a difference in the mean volume prediction between the models with and without the upper diameter as predictor has been observed. To analyze the causes of this difference, terrestrial laser scanning (TLS) was used to acquire a large dataset in Finland during 2017–2018. Field-measured predictors and volumes predicted using spline functions fitted to the TLS data were used to re-calibrate the current volume models. The trunk form is different in these two datasets. The form height is larger in the new data for all diameter classes, which indicates that the tree trunks are more slender than they used to be. One probable reason for this change is the increase in stand densities, which is at least partly due to changed forest management. In models with both dbh and h as predictors, the volume is smaller a given h class in the data new data than in the old data, and vice versa for the diameter classes. The differences between the old and new models were largest with pine and smallest with birch.

  • Kangas, Natural Resources Institute Finland (Luke), Yliopistokatu 6 B, FI-80100 Joensuu, Finland ORCID ID: https://orcid.org/0000-0002-8637-5668 E-mail: annika.kangas@luke.fi (email)
  • Henttonen, Natural Resources Institute Finland (Luke), Latokartanonkaari 9, FI-00790 Helsinki, Finland ORCID ID:E-mail: helena.henttonen@luke.fi
  • Pitkänen, Natural Resources Institute Finland (Luke), Latokartanonkaari 9, FI-00790 Helsinki, Finland ORCID ID: https://orcid.org/0000-0001-5389-8713 E-mail: timo.p.pitkanen@luke.fi
  • Sarkkola, Natural Resources Institute Finland (Luke), Latokartanonkaari 9, FI-00790 Helsinki, Finland ORCID ID:E-mail: sakari.sarkkola@luke.fi
  • Heikkinen, Natural Resources Institute Finland (Luke), Latokartanonkaari 9, FI-00790 Helsinki, Finland ORCID ID: https://orcid.org/0000-0003-3527-774X E-mail: juha.heikkinen@luke.fi
article id 10389, category Research article
Juho Matala, Harri Kilpeläinen, Henrik Heräjärvi, Tapio Wall, Erkki Verkasalo. (2020). Sawlog quality and tree dimensions of Scots pine 34 years after artificial moose browsing damage. Silva Fennica vol. 54 no. 3 article id 10389. https://doi.org/10.14214/sf.10389
Highlights: The first controlled, long-term, experimental study on the tree dimensions and sawlog quality after moose damage; The trees damaged at the seedling stage had a smaller diameter, height, and tree volume at the end of the experiment; The heavier the clipping treatment, the more likely the stem form deteriorated; Deteriorated stem form and vertical branches were the most typical defects.

Moose (Alces alces L.) browsing causes severe damage in Scots pine (Pinus sylvestris L.) seedling stands. The effects of this damage on the quality of sawlogs were studied in a long-term controlled experiment. This article reports the stem size and external quality characteristics of Scots pine stems 34 years after artificial moose browsing damage. Damaging the trees by clipping the main stem at the seedling stage reduced the diameter, height, and tree volume of the trees at the end of the experiment. The tree growth reduction was dependent on the severity of clipping. The differences between the damaged and the control trees were more obvious in diameter than in height at the time of final felling. Stem form defects and vertical branches were the most typical externally detectable defects caused by clipping. Defects in the butt logs were detected in 71–89% of the damaged trees, depending on the clipping treatment severity. The stronger the clipping treatment, the more likely the stem form was defected and the more commonly were vertical branches and crooks detected in the stems. The results indicate that both tree dimensions and stem quality suffer from moose browsing. The findings of this controlled experiment more likely underestimate than overestimate the damage in comparison to real moose browsing. Further analyses are required to assess the effects of browsing damage on the internal quality of sawlogs and subsequent economic outcomes.

  • Matala, Natural Resources Institute Finland (Luke), Natural resources, Yliopistokatu 6B, FI-80101 Joensuu, Finland ORCID ID:E-mail: juho.matala@luke.fi (email)
  • Kilpeläinen, Natural Resources Institute Finland (Luke), Bioeconomy and environment, Yliopistokatu 6B, FI-80101 Joensuu, Finland ORCID ID:E-mail: harri.kilpelainen@luke.fi
  • Heräjärvi, Natural Resources Institute Finland (Luke), Production systems, Yliopistokatu 6B, FI-80101 Joensuu, Finland ORCID ID:E-mail: henrik.herajarvi@luke.fi
  • Wall, Natural Resources Institute Finland (Luke), Research infrastructure services, Yliopistokatu 6B, FI-80101 Joensuu, Finland ORCID ID:E-mail: tapio.wall@luke.fi
  • Verkasalo, Natural Resources Institute Finland (Luke), Production systems, Yliopistokatu 6B, FI-80101 Joensuu, Finland ORCID ID:E-mail: erkki.verkasalo@luke.fi
article id 10373, category Research article
Chintan Sheth, Aparajita Datta, Devathi Parashuram. (2020). Persistent loss of biologically-rich tropical forests in the Indian Eastern Himalaya. Silva Fennica vol. 54 no. 3 article id 10373. https://doi.org/10.14214/sf.10373
Highlights: We found a high rate of deforestation occurring in a state managed reserve forest in Indian Eastern Himalaya; Fine-scale analysis showed considerable forest loss around nesting trees for hornbills; Forest monitoring, protection and honest governance are required to effectively protect forests in the Eastern Himalaya biodiversity hotspot.

Using fine-resolution satellite imagery from multiple satellite data products, we assessed the change in forest cover of a state-managed Reserve Forest (RF) located in India’s Eastern Himalaya biodiversity hot-spot. 4.6% of forest cover was lost from Papum RF between 2013 and 2017 at the rate of 8.2 km2 year–1. Three species of hornbills: Great Hornbill Buceros bicornis Linnaeus, 1758, Wreathed Hornbill Rhyticeros undulatus (Shaw, 1811) and Oriental Pied Hornbill Anthracoceros albirostris (Shaw, 1808), that are functionally important are found here with nesting habitat in the areas affected by illegal logging. Therefore, we assessed the habitat loss within a 1 km radius around 29 nest trees. From 2011 to 2019, forest cover declined from 38.55 km2 to 21.94 km2 around these hornbill nest trees. Illegal logging is the main driver that is depleting forest cover within this important bird area. Our results highlight the ongoing threats to biologically-rich forests and the need for urgent measures to halt this loss. We suggest that this study has practical implications for the monitoring and governance of state-managed forests in Arunachal Pradesh.

  • Sheth, #4 Ananda Nilaya, 4th Main Road, Siddhivinayaka Layout, Bengaluru 560097, Karnataka, India ORCID ID:E-mail: chintz604@gmail.com
  • Datta, Nature Conservation Foundation, 1311,“Amritha”, 12th Main, Vijayanagar 1st Stage, Mysore 570017, Karnataka, India ORCID ID:E-mail: aparajita@ncf-india.org (email)
  • Parashuram, Nature Conservation Foundation, 1311,“Amritha”, 12th Main, Vijayanagar 1st Stage, Mysore 570017, Karnataka, India; Department of Geography, University of Cambridge, CB2 3EN, United Kingdom ORCID ID:E-mail: dp608@cam.ac.uk
article id 10355, category Research article
Grzegorz Szewczyk, Raffaele Spinelli, Natascia Magagnotti, Paweł Tylek, Janusz M. Sowa, Piotr Rudy, Dominika Gaj-Gielarowiec. (2020). The mental workload of harvester operators working in steep terrain conditions. Silva Fennica vol. 54 no. 3 article id 10355. https://doi.org/10.14214/sf.10355
Highlights: We analysed a harvester operator’s perception of his work environment as slope gradient increased; Increasingly difficult work conditions (steeper terrain) were reflected by increased eyeball activity; Fixation duration increased with slope gradient, while the duration of saccades was shorter; Variation of the eyeball movement cycles was also related to work difficulty caused by slope gradient.

The use of modern multi-functional forestry machines has already been associated with central nervous system fatigue induced by high mental workload. As these machines are being used under increasingly difficult terrain conditions, further knowledge is required on the expected aggravation of operators’ mental workload, so that suitable work/rest schedules can be developed. Within such a context, the aim of this study was to gauge aggravations of mental workload derived from increasing slope gradient. Measurements of eye activity were obtained from a representative harvester operator working in corridors with the following mean inclinations: 9%, 23% and 47%. The duration, frequency and trajectory of eye movements were used to determine the harvester operator’s mental workload, on the assumption that worsening work conditions would be reflected by increased eyeball activity. The number of fixations during the performance of all tasks increased with the increasing slope gradient. Similarly, fixation duration increased with slope gradient. The mean duration of saccades when working on a 23% slope was 5% shorter compared to work under a 9% gradient. A further significant shortening of saccade duration (~22%) occurred when working on a 47% slope. The good match between eye activity cycles and work cycles, visible especially on steep slopes, indicates that mental workload is related to work conditions. Overall, operating a forest harvester on steep slopes results in a greatly increased mental workload and calls for suitable rest schedules.

  • Szewczyk, University of Agriculture in Krakow; al. 29 Listopada 46, 31-425 Kraków, Poland ORCID ID:E-mail: rlszewcz@cyf-kr.edu.pl (email)
  • Spinelli, National Research Council of Italy, Firenze, via Madonna del Piano, 10 50019 – Sesto Fiorentino, Italy ORCID ID:E-mail: spinelli@ivalsa.cnr.it
  • Magagnotti, National Research Council of Italy, Firenze, via Madonna del Piano, 10 50019 – Sesto Fiorentino, Italy ORCID ID:E-mail: natascia.magagnotti@ibe.cnr.it
  • Tylek, University of Agriculture in Krakow; al. 29 Listopada 46, 31-425 Kraków, Poland ORCID ID:E-mail: rltylek@cyf-kr.edu.pl
  • Sowa, University of Agriculture in Krakow; al. 29 Listopada 46, 31-425 Kraków, Poland ORCID ID:E-mail: janusz.sowa@urk.edu.pl
  • Rudy, State Forests, Biłgoraj Forest District, ul. Zamojska 96, 23-400 Biłgoraj, Poland ORCID ID:E-mail: rudy.piotrek@o2.pl
  • Gaj-Gielarowiec, State Forests, Barycz Forest District, Barycz 69, 26-200 Końskie, Poland ORCID ID:E-mail: dominika.gaj@gmail.com
article id 10341, category Research article
Arta Bārdule, Edgars Jūrmalis, Zane Lībiete, Ilze Pauliņa, Jānis Donis, Agita Treimane. (2020). Use of retail market data to assess prices and flows of non-wood forest products in Latvia. Silva Fennica vol. 54 no. 3 article id 10341. https://doi.org/10.14214/sf.10341
Highlights: Retail prices of non-wood forest products (NWFPs) may be used to study lifestyle-related consumption patterns; While retail sales of NWFPs may increase household budgets, this source of income is highly variable due to varying meteorological conditions; NWFP retail price analysis illustrates aspect of household economies not recorded in official statistics and cash flows of declared income.

In northern Europe, largest part of non-wood forest products (NWFPs) are gathered for recreational purposes and household consumption, but considerable amount of forest berries and mushrooms are sold as well. Retail market, largely invisible for the official statistics, reveals the lifestyle-related aspects of NWFP trade and may help to understand the flows of this ecosystem service when information on wholesale trade is inaccessible. The prices and flows of most common NWFPs – edible berries, mushrooms and tree sap – in the retail market in Latvia in 2017 and 2018 were analysed based on direct interviews with the sellers in marketplaces and telephone interviews with online retailers. The mean retail prices of NWFPs were compared between statistical regions and years and correlated with socio-economic data and forest characteristics. The directions of the NWFP flows were analysed according to the place of origin and place of retail sales. The highest prices were recorded for stinkhorn (Phallus impudicus Pers.) and Boletes spp. among mushrooms, for wild strawberries (Fragaria vesca L.) among berries and for maple (Acer platanoides L.) sap in the product group of tree sap. The retail price of the same products differed between years, most likely due to the product availability, largely caused by meteorological conditions. In more than half of the cases of recorded sales, NWFPs were consumed in the same region as they were gathered. For other cases of sales, the capital, Rīga, was the main service benefitting area of NWFP retail trade, and the largest part of the products originated from the two closest statistical regions.

  • Bārdule, Latvian State Forest Research Institute “Silava”, Rigas str. 111, Salaspils, Latvia, LV-2169 ORCID ID:E-mail: arta.bardule@silava.lv (email)
  • Jūrmalis, Latvian State Forest Research Institute “Silava”, Rigas str. 111, Salaspils, Latvia, LV-2169 ORCID ID:E-mail: edgars.jurmalis@silava.lv
  • Lībiete, Latvian State Forest Research Institute “Silava”, Rigas str. 111, Salaspils, Latvia, LV-2169 ORCID ID:E-mail: zane.libiete@silava.lv
  • Pauliņa, Latvian State Forest Research Institute “Silava”, Rigas str. 111, Salaspils, Latvia, LV-2169 ORCID ID:E-mail: paulina.ilze@gmail.com
  • Donis, Latvian State Forest Research Institute “Silava”, Rigas str. 111, Salaspils, Latvia, LV-2169 ORCID ID:E-mail: janis.donis@silava.lv
  • Treimane, Latvian State Forest Research Institute “Silava”, Rigas str. 111, Salaspils, Latvia, LV-2169; University of Latvia, Jelgavas str. 1, Riga, Latvia, LV-1004 ORCID ID:E-mail: agita.treimane@silava.lv
article id 10284, category Research article
Togtokhbayar Erdene-Ochir , Futoshi Ishiguri, Ikumi Nezu, Bayasaa Tumenjargal, Bayartsesteg Baasan, Ganbaatar Chultem, Jyunichi Ohshima, Shinso Yokota. (2020). Utilization potential of naturally regenerated Mongolian Betula platyphylla wood based on growth characteristics and wood properties. Silva Fennica vol. 54 no. 3 article id 10284. https://doi.org/10.14214/sf.10284
Highlights: Wood with high density and high compressive strength can be obtained near to the bark of Betula platyphylla trees; Basic density of B. platyphylla wood may be predicted by the stress-wave velocity of stems; Growth characteristics are positively correlated with stress-wave velocity and basic density; Early evaluation of basic density is possible when using the wood at 2 cm from the pith: A significant between-site variation was found in the basic density at the position from the 1st to the 15th annual ring from the pith; Wood from B. platyphylla trees grown in Mongolia may be used for industrial products equally to the same species in other countries.

To preliminary evaluate the potential wood utilization of Betula platyphylla Sukaczev trees naturally regenerated in Mongolia, growth characteristics (stem diameter and tree height), wood properties (annual ring width, basic density, and compressive strength parallel to grain at the green condition) of core samples, and stress-wave velocity in stems were investigated for Betula platyphylla trees grown naturally in three different sites in Selenge, Mongolia. Betula platyphylla trees, naturally grown in Nikko, Japan, were also examined to compare wood properties between the two regions. The mean values of stem diameter, tree height, stress-wave velocity of stems, annual ring width, basic density, and compressive strength parallel to grain at green condition in Mongolian B. platyphylla were 17.6 cm, 14.1 m, 3.50 km s–1, 1.27 mm, 0.51 g cm–3, and 20.4 MPa, respectively. Basic density and compressive strength were decreased first from the pith, and then gradually increased toward the bark. The wood properties of B. platyphylla trees grown naturally in Mongolia were similar to those in B. platyphylla trees grown in Japan. Growth characteristics, especially stem diameter, were positively correlated with the stress-wave velocity of stems and basic density. Early evaluation of basic density in B. platyphylla trees is possible by using wood located 2 cm from the pith. Basic density at the position from the 1st to the 15th annual ring from the pith showed significant between-site differences in Mongolian B. platyphylla. Based on the results, it is concluded that the wood of B. platyphylla trees grown in Mongolia may be used for industrial products as well as those from similar species in other countries.

  • Erdene-Ochir , School of Agriculture, Utsunomiya University, Utsunomiya, Tochigi 321-8505, Japan; United Graduate School of Agricultural Science, Tokyo University of Agriculture and Technology, Fuchu, Tokyo 183-8509, Japan; Training and Research Institute of Forestry and Wood Industry, Mongolian University of Science and Technology, Ulaanbaatar 14191, Mongolia ORCID ID:E-mail: togtokhbayarerdeneochir@gmail.com
  • Ishiguri, School of Agriculture, Utsunomiya University, Utsunomiya, Tochigi 321-8505, Japan ORCID ID:E-mail: ishiguri@cc.utsunomiya-u.ac.jp (email)
  • Nezu, School of Agriculture, Utsunomiya University, Utsunomiya, Tochigi 321-8505, Japan ORCID ID:E-mail: zoo-sk3.primo@outlook.jp
  • Tumenjargal, School of Agriculture, Utsunomiya University, Utsunomiya, Tochigi 321-8505, Japan; United Graduate School of Agricultural Science, Tokyo University of Agriculture and Technology, Fuchu, Tokyo 183-8509, Japan; Training and Research Institute of Forestry and Wood Industry, Mongolian University of Science and Technology, Ulaanbaatar 14191, Mongolia ORCID ID:E-mail: t_bayasaa88@yahoo.com
  • Baasan, Training and Research Institute of Forestry and Wood Industry, Mongolian University of Science and Technology, Ulaanbaatar 14191, Mongolia ORCID ID:E-mail: bayartsetseg@must.edu.mn
  • Chultem, Training and Research Institute of Forestry and Wood Industry, Mongolian University of Science and Technology, Ulaanbaatar 14191, Mongolia ORCID ID:E-mail: ganbaatar_ch@must.edu.mn
  • Ohshima, School of Agriculture, Utsunomiya University, Utsunomiya, Tochigi 321-8505, Japan ORCID ID:E-mail: joshima@cc.utsunomiya-u.ac.jp
  • Yokota, School of Agriculture, Utsunomiya University, Utsunomiya, Tochigi 321-8505, Japan ORCID ID:E-mail: yokotas@cc.utsunomiya-u.ac.jp
article id 10273, category Research article
Lasse Aro, Anssi Ahtikoski, Jyrki Hytönen. (2020). Profitability of growing Scots pine on cutaway peatlands. Silva Fennica vol. 54 no. 3 article id 10273. https://doi.org/10.14214/sf.10273
Highlights: The potential wood production on cutaway peatlands can be high; Afforestation with seeding or planting was profitable at 3% rate of interest; In northern Finland, the afforestation method, ditch spacing and fertilization affected the bare land value.

A major after-use option for former peat harvesting areas has been afforestation. The profitability of afforestation with Scots pine trees (Pinus sylvestris L.) was studied in two 31–32-year old experiments in southern and northern Finland. The stands were established by seeding and planting, and various fertilization treatments and drainage intensities were tested. The financial performance for each plot was assessed in three steps. First, the costs occurred during the measurement time were summed up according to their present value. Then, for the rest of the rotation (i.e., from the age of 31/32 onwards) the stand management was optimized in order to maximize the net present value (MaxNPV). Finally, bare land values (BLVs) were calculated by summing up the present value of costs and the MaxNPV and converting the sum of the series into infinity. The afforestation method did not affect the mean annual increment (MAI; 9.2–9.5 m3 ha–1 a–1) in the southern experiment. In the northern experiment the afforestation method, ditch spacing and fertilization had significant effects on the MAI of the stands. The average MAI of the planted pines was 8.9 m3 ha–1 a–1, and for seeded pines it was 7.5 m3 ha–1 a–1. The BLV at an interest rate of 3% was positive for all stands in both regions. In the northern region afforestation method, ditch spacing and fertilization also had a significant effect on the BLV. When the interest rate was 5%, almost two thirds of the stands had a negative BLV in both regions.

  • Aro, Natural Resources Institute Finland (Luke), Bioeconomy and environment, Itäinen Pitkäkatu 4A, FI-20520 Turku, Finland ORCID ID:E-mail: lasse.aro@luke.fi (email)
  • Ahtikoski, Natural Resources Institute Finland (Luke), Natural resources, Paavo Havaksentie 3, FI-90570 Oulu, Finland ORCID ID: https://orcid.org/0000-0003-1658-3813 E-mail: anssi.ahtikoski@luke.fi
  • Hytönen, Natural Resources Institute Finland (Luke), Natural resources, Teknologiakatu 7, FI-67100 Kokkola, Finland ORCID ID: http://orcid.org/0000-0001-8475-3568 E-mail: jyrki.hytonen@luke.fi
article id 10205, category Research article
Michel Soucy, Martin Béland. (2020). A crop tree release variant of precommercial thinning using a backpack mounted chain saw. Silva Fennica vol. 54 no. 3 article id 10205. https://doi.org/10.14214/sf.10205
Highlights: Backpack mounted chain saws offer an opportunity to effectively cut larger stems in precommercial thinning treatments compared to conventional circular blade brushsaws; Productivity in performing precommercial crop tree release (PCTR) in a hardwood stand using a backpack mounted chain saw varied between 0.22 to 0.47 ha h–1.

Although crop tree release (CTR) in hardwood stands is an accepted variant of precommercial thinning (PCT), the lack of an affordable and feasible method hinders its adoption. CTR implies selecting between 150 and 500 trees ha–1 when trees are between 7 and 12 m high and cutting only stems competing with the target crop trees. We performed a field trial of a CTR variant of PCT in a 27.8 ha hardwood stand using a backpack mounted chain saw. A detailed time study was performed to document the trial over 13 days. Compared to conventional PCT performed earlier in the life of a stand, precommercial crop tree release required cutting larger stems, which showed to be feasible and productive using a backpack mounted chain saw. Productivity varied between 0.22 to 0.47 ha h–1 during the trial, Although productivity could vary with stand characteristics and worker, this proof of concept trial demonstrates some of the potential uses that this new saw configuration offers and sets the basis for an eventual larger scale deployment of this treatment.

  • Soucy, Université de Moncton, 165 boulevard Hébert, Edmundston, N.-B. Canada, E3V 2S8, (506) 737-5248 ORCID ID: https://orcid.org/0000-0003-0531-5549 E-mail: michel.soucy@umoncton.ca
  • Béland, Université de Moncton, 165 boulevard Hébert, Edmundston, N.-B. Canada, E3V 2S8, (506) 737-5248 ORCID ID: https://orcid.org/0000-0001-8591-671X E-mail: martin.beland@umoncton.ca (email)
article id 10270, category Research article
Aarne Hovi, Matti Mõttus, Jussi Juola, Farshid Manoocheri, Erkki Ikonen, Miina Rautiainen. (2020). Evaluating the performance of a double integrating sphere in measurement of reflectance, transmittance, and albedo of coniferous needles. Silva Fennica vol. 54 no. 2 article id 10270. https://doi.org/10.14214/sf.10270
Highlights: Adaptation of a compact double integrating sphere for spectral measurements of coniferous needles; Double integrating sphere is fast to operate and suitable for monitoring purposes and collection of large spectral databases; Measured spectra showed negative bias, which could potentially be reduced by building an optimized measurement setup.

Leaf reflectance and transmittance spectra are essential information in many applications such as developing remote sensing methods, computing shortwave energy balance (albedo) of forest canopies, and monitoring health or stress of trees. Measurement of coniferous needle spectra has usually been carried out with single integrating spheres, which has involved a lot of tedious manual work. A small double integrating sphere would make the measurements considerably faster, because of its ease of operation and small sample sizes required. Here we applied a compact double integrating sphere setup, used previously for measurement of broad leaves, for measurement of coniferous needles. Test measurements with the double integrating sphere showed relative underestimation of needle albedo by 5–39% compared to a well-established single integrating sphere setup. A small part of the bias can be explained by the bias of the single sphere. Yet the observed bias is quite significant if absolute accuracy of measurements is required. For relative measurements, e.g. for monitoring development of needle spectra over time, the double sphere system provides notable improvement. Furthermore, it might be possible to reduce the bias by building an optimized measurement setup that minimizes absorption losses in the sample port. Our study indicates that double spheres, after some technical improvement, may provide a new and fast way to collect extensive spectral libraries of tree species.

  • Hovi, Aalto University, School of Engineering, Department of Built Environment, P.O.Box 14100, FI-00760 Aalto, Finland ORCID ID: https://orcid.org/0000-0002-4384-5279 E-mail: aarne.hovi@aalto.fi (email)
  • Mõttus, VTT Technical Research Centre Finland, P.O. Box 1000, FI-02044 VTT, Finland ORCID ID: https://orcid.org/0000-0002-2745-1966 E-mail: matti.mottus@gmail.com
  • Juola, Aalto University, School of Engineering, Department of Built Environment, P.O.Box 14100, FI-00760 Aalto, Finland ORCID ID:E-mail: jussi.juola@aalto.fi
  • Manoocheri, Aalto University, School of Electrical Engineering, Metrology Research Institute, Maarintie 8, FI-02150 Espoo, Finland ORCID ID: https://orcid.org/0000-0003-3935-3930 E-mail: farshid.manoocheri@aalto.fi
  • Ikonen, VTT Technical Research Centre Finland, P.O. Box 1000, FI-02044 VTT, Finland; Aalto University, School of Electrical Engineering, Metrology Research Institute, Maarintie 8, FI-02150 Espoo, Finland ORCID ID: https://orcid.org/0000-0001-6444-5330 E-mail: erkki.ikonen@aalto.fi
  • Rautiainen, Aalto University, School of Engineering, Department of Built Environment, P.O.Box 14100, FI-00760 Aalto, Finland; Aalto University, School of Electrical Engineering, Department of Electronics and Nanoengineering, P.O. Box 15500, FI-00760 Aalto, Finland ORCID ID: https://orcid.org/0000-0002-6568-3258 E-mail: miina.a.rautiainen@aalto.fi
article id 10259, category Research article
Jyrki Hytönen, Hannu Hökkä. (2020). Comparison of granulated and loose ash in fertilisation of Scots pine on peatland. Silva Fennica vol. 54 no. 2 article id 10259. https://doi.org/10.14214/sf.10259
Highlights: Granulated ash and commercial PK fertilizer increased stand growth in similar way during 15-year study period; Loose ash gave stronger and faster response than granulated ash.

The effects of wood ash fertilisation on tree nutrition and growth on forested peatlands has been studied using loose ash, but in practice, ash fertilisation is done almost exclusively with granulated ash. In this study, the effects of granulated ash and loose ash (both 5 Mg ha–1) on the growth and nutrition of Scots pine (Pinus sylvestris L.) stands were compared between a nitrogen-poor and a nitrogen-rich site over 15 years. On the nitrogen-rich site, wood ash application was also compared with commercial PK fertilisation. On the nitrogen-rich site, mean stand volume growth increase over unfertilised control treatment during the 15 year study period using granulated ash and commercial PK fertiliser was of the same magnitude (on average, 2.2–2.3 m3 ha–1 a–1). However, when loose ash was used growth increase over control was higher (3.7 m3 ha–1 a–1). On the nitrogen-poor site, the mean growth increase gained by loose or granulated ash (1.4–1.5 m3 ha–1 a–1) over the unfertilised control treatment was not significant. Fertilisation with loose ash or PK increased foliar P, K and B concentrations already in the first or second growing season, following fertilisation on both sites. Granulated ash increased foliar P concentrations on the nitrogen-rich site less than loose ash. After an initial increase, foliar P, K and B concentrations decreased at the end of study period. On the nitrogen-poor site, foliar P concentrations were below the deficiency limit by the end of the study period.

  • Hytönen, Natural Resources Institute Finland, Natural Resources, Teknologiakatu 7, FI-67100 Kokkola, Finland ORCID ID: https://orcid.org/0000-0001-8475-3568 E-mail: jyrki.hytonen@luke.fi (email)
  • Hökkä, Natural Resources Institute Finland, Natural Resources, Paavo Havaksentie 3, FI-90570 Oulu, Finland ORCID ID:E-mail: hannu.hokka@luke.fi
article id 10247, category Research article
Agnese Marcelli, Walter Mattioli, Nicola Puletti, Francesco Chianucci, Damiano Gianelle, Mirko Grotti, Gherardo Chirici, Giovanni D' Amico, Saverio Francini, Davide Travaglini, Lorenzo Fattorini, Piermaria Corona. (2020). Large-scale two-phase estimation of wood production by poplar plantations exploiting Sentinel-2 data as auxiliary information. Silva Fennica vol. 54 no. 2 article id 10247. https://doi.org/10.14214/sf.10247
Highlights: A two-phase sampling for large-scale assessment of fast-growing forest crops is developed; Vegetation indices from Sentinel-2 are exploited in a linear regression estimator; The linear regression estimator turns out to be better than the estimator based on the sole sample information; The approach represents a reference for supporting outside-forest resource monitoring and assessment.

Growing demand for wood products, combined with efforts to conserve natural forests, have supported a steady increase in the global extent of planted forests. Here, a two-phase sampling strategy for large-scale assessment of the total area and the total wood volume of fast-growing forest tree crops within agricultural land is presented. The first phase is performed using tessellation stratified sampling on high-resolution remotely sensed imagery and is sufficient for estimating the total area of plantations by means of a Monte Carlo integration estimator. The second phase is performed using stratified sampling of the plantations selected in the first phase and is aimed at estimating total wood volume by means of an approximation of the first-phase Horvitz-Thompson estimator. Vegetation indices from Sentinel-2 are exploited as freely available auxiliary information in a linear regression estimator to improve the design-based precision of the estimator based on the sole sample data. Estimators of the totals and of the design-based variances of total estimators are presented. A simulation study is developed in order to check the design-based performance of the two alternative estimators under several artificial distributions supposed for poplar plantations (random, clustered, spatially trended). An application in Northern Italy is also reported. The regression estimator turns out to be invariably better than that based on the sole sample information. Possible integrations of the proposed sampling scheme with conventional national forest inventories adopting tessellation stratified sampling in the first phase are discussed.

  • Marcelli, University of Tuscia, Department for Innovation in Biological, Agro-food and Forest systems, Viterbo, Italy; Fondazione Edmund Mach, Department of Sustainable Agro-Ecosystems and Bioresources, Research and Innovation Centre, San Michele all’Adige, Italy ORCID ID:E-mail: agnese.marcelli@student.unisi.it (email)
  • Mattioli, University of Tuscia, Department for Innovation in Biological, Agro-food and Forest systems, Viterbo, Italy; CREA, Research Centre for Forestry and Wood, Arezzo, Italy ORCID ID:E-mail: walter.mattioli@crea.gov.it
  • Puletti, CREA, Research Centre for Forestry and Wood, Arezzo, Italy ORCID ID:E-mail: nicola.puletti@crea.gov.it
  • Chianucci, CREA, Research Centre for Forestry and Wood, Arezzo, Italy ORCID ID:E-mail: fchianucci@gmail.com
  • Gianelle, Fondazione Edmund Mach, Department of Sustainable Agro-Ecosystems and Bioresources, Research and Innovation Centre, San Michele all’Adige, Italy ORCID ID:E-mail: damiano.gianelle@fmach.it
  • Grotti, CREA, Research Centre for Forestry and Wood, Arezzo, Italy; University of Roma La Sapienza, Department of Architecture and Design, Rome, Italy ORCID ID:E-mail: mirkogrotti@gmail.com
  • Chirici, University of Firenze, Department of Agriculture, Food, Environment and Forestry, Florence, Italy ORCID ID:E-mail: gherardo.chirici@unifi.it
  • D' Amico, University of Firenze, Department of Agriculture, Food, Environment and Forestry, Florence, Italy ORCID ID:E-mail: giovanni.damico@unifi.it
  • Francini, University of Firenze, Department of Agriculture, Food, Environment and Forestry, Florence, Italy; University of Molise, Department of Agricultural, Environmental and Food Sciences, Campobasso, Italy ORCID ID:E-mail: saverio.francini@gmail.com
  • Travaglini, University of Firenze, Department of Agriculture, Food, Environment and Forestry, Florence, Italy ORCID ID:E-mail: davide.travaglini@unifi.it
  • Fattorini, University of Siena, Department of Economics and Statistics, Siena, Italy ORCID ID:E-mail: lorenzo.fattorini@unisi.it
  • Corona, CREA, Research Centre for Forestry and Wood, Arezzo, Italy ORCID ID:E-mail: piermaria.corona@crea.gov.it
article id 10220, category Research article
Arnis Gailis, Pauls Zeltiņš, Andis Purviņš, Juris Augustovs, Valts Vīndedzis, Inga Zariņa, Āris Jansons. (2020). Genetic parameters of growth and quality traits in open-pollinated silver birch progeny tests. Silva Fennica vol. 54 no. 2 article id 10220. https://doi.org/10.14214/sf.10220
Highlights: Growth and stem quality traits were under strong genetic control; Weak genetic correlations between tree growth and stem quality were found; Strong age-age and type-B correlations suggest robust improvement over time and different environments; Simultaneous improvement of growth and stem quality might be applicable.

Genetic parameters of growth and stem quality traits were estimated for open-pollinated silver birch Betula pendula Roth progenies in Latvia at the age of 10 and 14 years. Tree height and stem volume were found to be under strong genetic control at both inventories (narrow-sense heritabilities varied from 0.41 to 0.66). Mainly low heritabilities were found for stem defects, yet genetic control of branch diameter, stem straightness and overall stem quality varied from low to high depending on study site. High additive genetic coefficient of variation was found for stem volume (25.3–32.5%). Genetic correlations among growth traits were strong and positive (0.90–0.99). Mainly weak genetic correlations between growth and quality traits implied simultaneous improvement. Still, strong negative correlations between branch angle and stem straightness might result in enlarged knot size for straighter logs. The genetic age-age correlations were strong. Weak genotype by environment interaction and stability of best genotypes over different sites was indicated by strong genetic correlations between trials. Each growth or quality trait alone showed substantial improvement in terms of estimated genetic gain (up to 62% over trial mean for stem volume). Therefore, selection index combining both growth and stem quality may be developed.

  • Gailis, Latvian State Forest Research Institute Silava, 111 Rigas street, Salaspils LV-2169, Latvia ORCID ID:E-mail: arnis.gailis@silava.lv
  • Zeltiņš, Latvian State Forest Research Institute Silava, 111 Rigas street, Salaspils LV-2169, Latvia ORCID ID: https://orcid.org/0000-0002-6286-5814 E-mail: pauls.zeltins@silava.lv (email)
  • Purviņš, Latvian State Forest Research Institute Silava, 111 Rigas street, Salaspils LV-2169, Latvia ORCID ID:E-mail: andis.purvins@silava.lv
  • Augustovs, Latvian State Forest Research Institute Silava, 111 Rigas street, Salaspils LV-2169, Latvia ORCID ID:E-mail: juris.augustovs@silava.lv
  • Vīndedzis, Latvian State Forest Research Institute Silava, 111 Rigas street, Salaspils LV-2169, Latvia ORCID ID:E-mail: valts.vindedzis@silava.lv
  • Zariņa, Latvian State Forest Research Institute Silava, 111 Rigas street, Salaspils LV-2169, Latvia ORCID ID:E-mail: inga.zarina@silava.lv
  • Jansons, Latvian State Forest Research Institute Silava, 111 Rigas street, Salaspils LV-2169, Latvia ORCID ID:E-mail: aris.jansons@silava.lv
article id 10211, category Research article
Gernot Erber, Raffaele Spinelli. (2020). Timber extraction by cable yarding on flat and wet terrain: a survey of cable yarder manufacturer’s experience. Silva Fennica vol. 54 no. 2 article id 10211. https://doi.org/10.14214/sf.10211
Highlights: Survey of all European cable yarder manufacturers on flat-terrain yarding; Manufacturers are frequently contacted concerning flat-terrain yarding; Forest resource inaccessibility, regulatory and environmental considerations are most important motivations; Lack of clearance, tree stability and installation costs are major challenges; Mobile, self-anchoring tail spar is considered a chief adaptation; Cost-competitiveness with ground-based systems cannot be achieved without subsidies; Increasing environmental awareness and climate change present opportunity to expand flat-terrain cable yarding.

Cable yarding is a general solution for load handling on sites not accessible to ground-based machinery, and is typically associated with steep terrain. On flat terrain, such conditions can primarily be found on soft or wet soils, most frequently encountered in Central and Northern European countries. Today, changed environmental and market conditions may offer an unprecedented opportunity to the actual implementation of cable yarding on flat terrain in commercial operations. The study goal was to collect cable yarder manufacturers experience regarding the use and adaption of cable yarding technology on flat terrain. European manufacturers of cable yarding technology were interviewed about customer experience, particular challenges, adaptation potential, future potential and main hurdles for the expansion of cable yarding on flat terrain. Almost all manufacturers have received requests for flat-terrain yarding technology solutions, primarily from Germany. Temporal or permanent inaccessibility, regulatory or environmental reasons were the most frequent motivation for considering cable yarding technology. Installation was considered particularly challenging (clearance, stable anchoring). Potential adaptations included higher towers, artificial anchors, mechanized bunching before extraction and un-guyed yarder-systems. An artificial, highly mobile, self-anchoring tail spar was considered the most useful adaptation. While concerned about limited profitability and qualified labour shortage, most manufacturers demonstrated a positive or neutral view concerning the expansion of cable yarding on flat terrain. However, cable yarding is not considered to be cost-competitive wherever ground-based systems can be employed and cable yarding is not subsidized.

  • Erber, University of Natural Resources and Life Sciences Vienna, Department of Forest and Soil Sciences, Institute of Forest Engineering, Peter Jordan Strasse 82, 1190 Vienna, Austria ORCID ID: https://orcid.org/0000-0003-1606-5258 E-mail: gernot.erber@boku.ac.at (email)
  • Spinelli, CNR-IBE Consiglio Nazionale delle Ricerche-Istituto per la BioEconomia, Via Madonna del Piano 10, Sesto Fiorentino, Firenze, I-50019, Italy; AFORA, University of the Sunshine Coast, Locked Bag 4, Maroochydore, QLD, Australia ORCID ID: https://orcid.org/0000-0001-9545-1004 E-mail: spinelli@ivalsa.cnr.it
article id 10167, category Research article
Cheng Bai, Shixue You, Weipeng Ku, Qilin Dai, Zhengyi Wang, Mingshui Zhao, Shuquan Yu. (2020). Life form dynamics of the tree layer in evergreen and deciduous broad-leaved mixed forest during 1996–2017 in Tianmu Mountains, eastern China. Silva Fennica vol. 54 no. 2 article id 10167. https://doi.org/10.14214/sf.10167
Highlights: Biodiversity monitoring was performed over twenty one years in a 1 ha plot; Life form composition changed significantly between 1996 and 2017; Evergreen trees in the understory expanded upwards; Forests were currently dominated by evergreen trees.

In the forest areas of eastern China, there is a change from forest dominated by deciduous broad-leaved trees to forest dominated by evergreen broad-leaved trees as the latitude or altitude decreases. Different life forms have different survival strategies to deal with climate change, and studying the life form dynamics of the tree layers in the mixed forest in eastern China, with increasing temperature, can help us understand how the forest responds. This study was performed in a 1 ha plot in evergreen and deciduous broad-leaved mixed forest in Tianmu Mountain National Nature Reserve. Based on the data from two surveys (1996 and 2017), the changes in life form composition and biodiversity over the past 21 years were analyzed. We obtained the following results: (1) The proportion of evergreen trees increased from 55.0% in 1996 to 67.5% in 2017, and the dominance of evergreen species was enhanced. (2) The diversity of both life forms increased, and the tree species were more abundant. (3) The average annual recruitment rate of the evergreen species was 2.1% greater than their mortality rate, and the average annual recruitment rate of the deciduous species was 0.5% less than their mortality rate. (4) The competition among the trees in the small-diameter class (10 cm ≤ DBH < 20 cm) was fierce for many tree species. The proportion of the evergreen species in the small-diameter class was high. The life forms making up the mixed climax forest community has changed over the past 21 years, with the proportion and dominance of evergreen trees increasing significantly.

  • Bai, State Key Laboratory of Subtropical Silviculture, Zhejiang A&F University, Hangzhou 311300, China ORCID ID:E-mail: baicheng111@gmail.com
  • You, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310011, China ORCID ID:E-mail: sxyou@zju.edu.cn
  • Ku, State Key Laboratory of Subtropical Silviculture, Zhejiang A&F University, Hangzhou 311300, China ORCID ID:E-mail: 2732684475@qq.com
  • Dai, State Key Laboratory of Subtropical Silviculture, Zhejiang A&F University, Hangzhou 311300, China ORCID ID:E-mail: 757692949@qq.com
  • Wang, State Key Laboratory of Subtropical Silviculture, Zhejiang A&F University, Hangzhou 311300, China ORCID ID:E-mail: 237600341@qq.com
  • Zhao, Management Bureau of Tianmu Mountain National Nature Reserve, Hangzhou 311311, China ORCID ID:E-mail: 973659738@qq.com
  • Yu, State Key Laboratory of Subtropical Silviculture, Zhejiang A&F University, Hangzhou 311300, China ORCID ID:E-mail: yushq@zafu.edu.cn (email)
article id 10143, category Research article
Olga Grigorieva, Olga Brovkina, Alisher Saidov. (2020). An original method for tree species classification using multitemporal multispectral and hyperspectral satellite data. Silva Fennica vol. 54 no. 2 article id 10143. https://doi.org/10.14214/sf.10143
Highlights: Differences between spectral reflectance of tree species are statistically significant in the sub-seasons of spring, first half of summer, and main autumn; Classification using multitemporal multispectral data is more productive than is classification using a single hyperspectral image; the method improves recent forest mapping in the study regions.

This study proposes an original method for tree species classification by satellite remote sensing. The method uses multitemporal multispectral (Landsat OLI) and hyperspectral (Resurs-P) data acquired from determined vegetation periods. The method is based on an original database of spectral features taking into account seasonal variations of tree species spectra. Changes in the spectral signatures of forest classes are analyzed and new spectral–temporal features are created for the classification. Study sites are located in the Czech Republic and northwest (NW) Russia. The differences in spectral reflectance between tree species are shown as statistically significant in the sub-seasons of spring, first half of summer, and main autumn for both study sites. Most of the errors are related to the classification of deciduous species and misclassification of birch as pine (NW Russia site), pine as mixture of pine and spruce, and pine as mixture of spruce and beech (Czech site). Forest species are mapped with accuracy as high as 80% (NW Russia site) and 81% (Czech site). The classification using multitemporal multispectral data has a kappa coefficient 1.7 times higher than does that of classification using a single multispectral image and 1.3 times greater than that of the classification using single hyperspectral images. Potentially, classification accuracy can be improved by the method when applying multitemporal satellite hyperspectral data, such as in using new, near-future products EnMap and/or HyspIRI with high revisit time.

  • Grigorieva, A.F. Mozhaysky’s Military-Space Academy, Krasnogo Kursanta Street 19a, 197198, Saint Petersburg, Russia ORCID ID:E-mail: alenka12003@gmail.com
  • Brovkina, Global Change Research Institute CAS, Bělidla 986/4a, 603 00, Brno, Czech Republic ORCID ID:E-mail: brovkina.o@czechglobe.cz (email)
  • Saidov, A.F. Mozhaysky’s Military-Space Academy, Krasnogo Kursanta Street 19a, 197198, Saint Petersburg, Russia ORCID ID:E-mail: celestial.azura@gmail.com
article id 10243, category Research article
Laura Pikkarainen, Jaana Luoranen, Antti Kilpeläinen, Teppo Oijala, Heli Peltola. (2020). Comparison of planting success in one-year-old spring, summer and autumn plantings of Norway spruce and Scots pine under boreal conditions. Silva Fennica vol. 54 no. 1 article id 10243. https://doi.org/10.14214/sf.10243
Highlights: In Norway spruce, 84% of all plantings were successful, whereas in Scots pine, the corresponding number was 52%; The major reason for poor planting results was poor work quality; An extended planting season is possible for Norway spruce in southern and central Finland; In Scots pine, there are still large uncertainties in the success of summer and autumn plantings.

In Nordic countries, tree planting of seedlings is mainly performed during spring and early summer. Interest has increased in extending the planting window throughout the unfrozen growing season. This study compared the success of one-year-old spring, summer and autumn plantings in practical forestry in Norway spruce (Picea abies (L.) Karst.) and Scots pine (Pinus sylvestris L.) in southern and central Finland. Planting success was based on the number of viable seedlings per hectare relative to a species-specific target density. The influence of different factors to poor planting results were determined, including quality of site preparation and planting, and sources of natural damage. Overall, in Norway spruce, 85, 69 and 84% and in Scots pine 53, 55 and 40% of spring, summer and autumn plantings succeeded. In Norway spruce, the planting results were consistent between the southern and central regions, whereas in Scots pine, the success was slightly lower in the south. The poor work quality and a low density of appropriate planting spots, contributed to poor planting results, regardless of planting season, region or tree species. Considering different damages, especially mammal damage contributed to the failure of Scots pine spring plantings, whereas in summer plantings, corresponding single failure reason could not be identified. Based on our findings, extending the planting season of Norway spruce could be recommended in both regions. For Scots pine, there is still significant uncertainty about the success of summer and autumn plantings, partially due to the limited number of plantings available for analyses.

  • Pikkarainen, School of Forest Sciences, University of Eastern Finland, Yliopistonkatu 7, FI-80100 Joensuu, Finland ORCID ID:E-mail: laura.pikkarainen@uef.fi (email)
  • Luoranen, Natural Resources Institute Finland (Luke), Production Systems, Neulaniementie 5, FI-70210 Kuopio, Finland ORCID ID:E-mail: jaana.luoranen@luke.fi
  • Kilpeläinen, School of Forest Sciences, University of Eastern Finland, Yliopistonkatu 7, FI-80100 Joensuu, Finland ORCID ID:E-mail: antti.kilpelainen@uef.fi
  • Oijala, Metsä Group, Metsä Forest, Kuormaajantie 7, FI-40320 Jyväskylä, Finland ORCID ID:E-mail: teppo.oijala@metsagroup.com
  • Peltola, School of Forest Sciences, University of Eastern Finland, Yliopistonkatu 7, FI-80100 Joensuu, Finland ORCID ID:E-mail: heli.peltola@uef.fi
article id 10242, category Research article
Shisheng Long, Siqi Zeng, Falin Liu, Guangxing Wang. (2020). Influence of slope, aspect and competition index on the height-diameter relationship of Cyclobalanopsis glauca trees for improving prediction of height in mixed forests. Silva Fennica vol. 54 no. 1 article id 10242. https://doi.org/10.14214/sf.10242
Highlights: In this study, the effects of slope, aspect and competition index (CI) on the H-DBH relationship were explored and an improved CI was developed and included to improve predictions of Cyclobalanopsis glauca tree height; It was found that the effects were statistically significant and considering slope, aspect and CI for developing the H-DBH models significantly increased the H prediction accuracy.

Diameter at breast height (DBH) and height (H) of trees are two important variables used in forest management plans. However, collecting the measurements of H is time-consuming and costly. Instead, the H-DBH relationship is modeled and used to estimate H. But, ignoring the effects of slope, aspect and tree competition on the H-DBH relationship often impedes the improvement of H predictions. In this study, to improve predictions of Cyclobalanopsis glauca (Thunb.) Oerst. tree H in mixed forests, we compared eleven H-DBH models and examined the influence of slope and aspect on the H-DBH relationship using 426 trees. We then improved Hegyi competition index and explored its effect on the H predictions by including it in the selected models. Results showed 1) There were statistically significant effects of slope and aspect on the H-DBH relationship; 2) The log transformation and exponential model performed best for sunny- and shady-steep, respectively, and the Gompertz’s model was optimal for both sunny- and shady-gentle; 3) Compared with the whole dataset, the division of the data into the slope and aspect sub-datasets significantly reduced the RMSE of H predictions; 4) Compared with the selected models without competition index, adding the original Hegyi and improved Hegyi_I into the models improved the H predictions but only the models containing the improved Hegyi_I significantly increased the prediction accuracy at the significant level of 0.1. This study implied that modeling the H-DBH relationship under different slopes and aspects and including the improved Hegyi_I provided the great potential to improve the H predictions.

  • Long, Faculty of Forestry, Central South University of Forestry and Technology, Changsha, Hunan 410004, China ORCID ID:E-mail: shisheng3604@21cn.com
  • Zeng, Faculty of Forestry, Central South University of Forestry and Technology, Changsha, Hunan 410004, China ORCID ID:E-mail: zengsiqi@21cn.com
  • Liu, Faculty of Forestry, Central South University of Forestry and Technology, Changsha, Hunan 410004, China ORCID ID:E-mail: liufl680@126.com
  • Wang, Research Center of Forestry Remote Sensing & Information Engineering, Central South University of Forestry and Technology, Changsha 410004, China; Department of Geography and Environmental Resources, Southern Illinois University, Carbondale, IL 62901, USA ORCID ID:E-mail: gxwang@siu.edu (email)
article id 10215, category Research article
Korotimi Ouédraogo, Kangbéni Dimobe, Adjima Thiombiano. (2020). Allometric models for estimating aboveground biomass and carbon stock for Diospyros mespiliformis in West Africa. Silva Fennica vol. 54 no. 1 article id 10215. https://doi.org/10.14214/sf.10215
Highlights: Biomass estimation models developed for Diospyros mespiliformis; Models based on DBH alone predicted aboveground biomass with 97.11% accuracy; Published models had relative error between –72% and +98%; Models for branch and stem biomass were more accurate than those for leaf biomass.

Accurate estimates of aboveground biomass (AGB) strongly depend on the suitability and precision of allometric models. Diospyros mespiliformis Hochst. ex A. DC. is a key component of most sub-Sahara agroforestry systems and, one of the most economically important trees in Africa. Despite its importance, very few scientific information exists regarding its biomass and carbon storage potential. In this study direct method was used to develop site-specific biomass models for D. mespiliformis tree components in Burkina Faso. Allometric models were developed for stem, branch and leaf biomass using data from 39 tree harvested in Sudanian savannas of Burkina Faso. Diameter at breast height (DBH), tree height, crown diameter (CD) and basal diameter (D20) were regressed on biomass component using non-linear models with DBH alone, and DBH in combination with height and/or CD as predictor variables. Carbon content was estimated for each tree component using the ash method. Allometric models differed between the experimental sites, except for branch biomass models. Site-specific models developed in this study exhibited good model fit and performance, with explained variance of 81–98%. Using models developed from other areas would have underestimated or overestimated biomass by between –72% and +98%. Carbon content in aboveground components of D. mespiliformis in Tiogo, Boulon and Tapoa-Boopo was 55.40% ± 1.50, 55.52% ± 1.06 and 55.63% ± 1.00, respectively, and did not vary significantly (P-value = 0.909). Site-specific models developed in this study are useful tool for estimating carbon stocks and can be used to accurately estimate tree components biomass in vegetation growing under similar conditions.

  • Ouédraogo, University Joseph Ki-Zerbo, UFR/SVT, Laboratory of Plant Biology and Ecology, 03 B.P. 7021 Ouagadougou 03, Burkina Faso ORCID ID:E-mail: okorotimi@yahoo.fr (email)
  • Dimobe, University Joseph Ki-Zerbo, UFR/SVT, Laboratory of Plant Biology and Ecology, 03 B.P. 7021 Ouagadougou 03, Burkina Faso; University of Dédougou, Institut des Sciences de l’Environnement et du Développement Rural (ISEDR), BP 139 Dédougou, Burkina Faso; West African Science Service Center on Climate Change and Adapted Land Use, Competence Center, Avenue Muamar Ghadhafi, Ouagadougou, BP 9507, Burkina Faso ORCID ID: https://orcid.org/0000-0001-5536-9700 E-mail: kangbenidimobe@gmail.com
  • Thiombiano, University Joseph Ki-Zerbo, UFR/SVT, Laboratory of Plant Biology and Ecology, 03 B.P. 7021 Ouagadougou 03, Burkina Faso ORCID ID:E-mail: adjima_thiombiano@yahoo.fr
article id 10196, category Research article
Karri Uotila, Jari Miina, Timo Saksa, Ron Store, Kauko Kärkkäinen, Mika Härkönen. (2020). Low cost prediction of time consumption for pre-commercial thinning in Finland. Silva Fennica vol. 54 no. 1 article id 10196. https://doi.org/10.14214/sf.10196
Highlights: Time consumption (TC) in pre-commercial thinning (PCT) can be predicted by variables describing site and stands conditions and previous silvicultural management; Applying variables available in forest resources data the field-assessment of worksite difficulty factors is not needed; The TC model could facilitate the predictions of the labour costs of PCT in forest information systems.

The time consumption (TC) of pre-commercial thinning (PCT) varies greatly among sites, stands and forest workers. The TC in PCT is usually estimated by field-assessed work difficulty factors. In this study, a linear mixed model for the TC in PCT was prepared by utilizing forest resources data (FRD). The modelling data included 11 848 and validation data included 3035 worksites with TC information recorded by forest workers within the period of 2008–2018. The worksites represented a range of site and stand conditions across a broad geographical area in Finland. Site and stand characteristics and previous management logically explained the TC in PCT. The more fertile the site, the more working time was needed in PCT. On sites of medium fertility, TC in the initial PCT increased with stand age by 0.5 h ha–1 yr–1. Site wetness increased the TC. PCT in summer was more time consuming than in spring. Small areas were more time consuming to PCT per hectare than larger ones. The between-forest worker variation involved in the TC was as high as 35% of the variation unexplained by the TC model. The coefficient of determination in validation data was 19.3%, RMSE 4.75 h ha–1 and bias –1.6%. The TC model based on FRD was slightly less precise than the one based on field-assessed work difficulty factors (removal quantity and type and terrain difficulty): RMSE 4.9 h ha–1 vs. 4.1 h ha–1 (52% vs. 43%). The TC model could be connected to forest information systems where it would facilitate the predictions of the labour costs of PCT without field-assessing work difficulty factors.

  • Uotila, Natural Resources Institute Finland (Luke), Natural resources, Latokartanonkaari 9, FI-00790 Helsinki, Finland ORCID ID:E-mail: karri.uotila@luke.fi (email)
  • Miina, Natural Resources Institute Finland (Luke), Natural resources, Yliopistokatu 6 B, FI-80100 Joensuu, Finland ORCID ID:E-mail: jari.miina@luke.fi
  • Saksa, Natural Resources Institute Finland (Luke), Natural resources, Survontie 9, FI-40500 Jyväskylä, Finland ORCID ID:E-mail: timo.saksa@luke.fi
  • Store, Natural Resources Institute Finland (Luke), Bioeconomy and environment, Teknologiakatu 7, FI-67100 Kokkola, Finland ORCID ID:E-mail: ron.store@luke.fi
  • Kärkkäinen, ORCID ID:E-mail: kauko.karkkainen@gmail.com
  • Härkönen, Tornator Oyj, Pielisentie 2–6, FI-81700 Lieksa, Finland ORCID ID:E-mail: mika.harkonen@tornator.fi
article id 10163, category Research article
Uttam Thangjam, Uttam K. Sahoo, Pentile Thong. (2020). Characterization of morphometric, reproductive and seedling traits of Parkia timoriana in northeast India. Silva Fennica vol. 54 no. 1 article id 10163. https://doi.org/10.14214/sf.10163
Highlights: Among provenances, Pherema (P1) Serchip (P10) and Jiribam (P7) were associated with stress tolerant and better quality seedlings.; P1 gave the best result for seed traits including high germinability, P10 showed highest seedling vigour, while P7 corresponds to high-quality pod related traits; Variations in morphological, germinative and seedling growth characters of seeds across provenance further illustrate the importance of site selection for the production of better quality trees.

We studied variations on different traits of Parkia timoriana (D.C.) Merr. in twelve provenances systematically from their source of origin to a controlled environment where representative seedlings were grown. Among the provenances, P1 gave the best result for seed traits including germination traits, P7 for pod traits and P10 for seedling vigour. Effects of seasonal distribution of rainfall and temperature on seed and pod traits were also determined by computing multiple regression analysis. The results displayed winter rainfall and summer temperature as the most important factor determining pod and seed traits. Latitude also significantly (P < 0.001) affected PWT (r = 0.52), SWP (r = 0.46) and SW (r = 0.50). A common garden study for germination and seedling growth indicated P1 and P10 provenance as the best among all. Seeds drawn from P10 gave the highest seedling vigour with an average growth rate of 0.61 cm/day from 90th to 180th day. Highest broad-sense heritability values (h2) were observed in germination traits, followed by seedling collar diameter. The lowest h2 was observed for seedling height.

  • Thangjam, Department of Forestry, School of Earth Sciences & Natural Resource Management, Mizoram University, Aizawl-796004, Mizoram, India ORCID ID: https://orcid.org/0000-0003-1263-5348 E-mail: thangjam1987@gmail.com
  • Sahoo, Department of Forestry, School of Earth Sciences & Natural Resource Management, Mizoram University, Aizawl-796004, Mizoram, India ORCID ID: https://orcid.org/0000-0002-6524-1775 E-mail: uksahoo_2003@rediffmail.com (email)
  • Thong, Department of Forestry, School of Earth Sciences & Natural Resource Management, Mizoram University, Aizawl-796004, Mizoram, India ORCID ID: https://orcid.org/0000-0002-5358-181X E-mail: pentilethong@gmail.com
article id 10084, category Research article
Mihails Čugunovs, Eeva-Stiina Tuittila, Jari Kouki. (2020). Proximity to charred logs in burned forests likely affects decomposition processes in the soil. Silva Fennica vol. 54 no. 1 article id 10084. https://doi.org/10.14214/sf.10084
Highlights: Standardised organic substrate decomposition was tentatively observed to be faster adjacent to non-charred downed logs than away from the logs or adjacent to charred logs; A spatial linkage was observed between non-charred logs and decomposition in the soil in burned boreal forests; Proximity to a charred log may provide a micro-environment where decomposition rates differ from the surrounding forest soil.

We studied the spatial decomposition rates of standardised organic substrates in soils (burned boreal pine-dominated sub-xeric forests in eastern Finland), with respect to charred and non-charred coarse woody debris (CWD). Decomposition rates of rooibos plant litter inside teabags (C:N = 42.870 ± 1.841) and pressed-sheet Nordic hardwood pulp (consisting of mainly alpha-cellulose) were measured at 0.2 m distance from 20 charred (LC0.2) and 40 non-charred logs (LNC0.2). We also measured decomposition at 60 plots located 3–10 m away from downed logs (L3,10). The rooibos decomposition rate constant ‘k’ was 8.4% greater at the LNC0.2 logs than at the L3,10 or LC0.2 logs. Cellulose decomposed more completely in 1 micron mesh bags at LNC0.2 (44% of buried bags had leftover material) than at LC0.2 (76%) or L3,10 (70%). Decomposition of cellulose material was rapid but varied greatly between sampling plots. Our results indicate that decomposition of the standardised organic matter was more rapid close to CWD pieces than further away. However, only the plots located near non-charred logs (LNC0.2) exhibited high decomposition rates, with no corresponding increase observed at the charred logs (LC0.2). This suggests a possible noteworthy indirect effect of forest burning on soil organic matter (SOM) decomposition rates close to charred CWD after forest fires. We urge for more studies on this tentative observation as it may affect the estimates on how fires affect carbon cycling in forests.

  • Čugunovs, University of Eastern Finland, School of Forest Sciences, Yliopistokatu 7, P.O. Box 111, FI-80101 Joensuu, Finland ORCID ID:E-mail: mihails.cugunovs@gmail.com (email)
  • Tuittila, University of Eastern Finland, School of Forest Sciences, Yliopistokatu 7, P.O. Box 111, FI-80101 Joensuu, Finland ORCID ID: https://orcid.org/0000-0001-8861-3167 E-mail: eeva-stiina.tuittila@uef.fi
  • Kouki, University of Eastern Finland, School of Forest Sciences, Yliopistokatu 7, P.O. Box 111, FI-80101 Joensuu, Finland ORCID ID: https://orcid.org/0000-0003-2624-8592 E-mail: jari.kouki@uef.fi
article id 10051, category Research article
Anna-Kaisa Kosenius, Artti Juutinen, Liisa Tyrväinen. (2020). The role of state-owned commercial forests and firm features in nature-based tourism business performance. Silva Fennica vol. 54 no. 1 article id 10051. https://doi.org/10.14214/sf.10051
Highlights: State-owned commercial forests provide an important part of nature-based tourism enterprises’ service scope; Increase in turnover during five years vary depending on provided services; Entrepreneurial attitude associates with willingness to participate in a landscape and recreational value trading scheme; Increasing international demand for nature-based tourism promotes business possibilities, needs attention to forest environments and smooth co-operation between actors.

Nature-based tourism (NBT) is a growing industry within regions rich in natural amenities worldwide. An important feature of NBT business is the dependence on the quality of surrounding environment. This paper addresses the role of the management of commercial forests owned by the state in Finnish Lapland. The paper explores the NBT entrepreneurs’ willingness to participate in a proposed new landscape and recreational value trading (LRVT) and elaborates the effect of entrepreneur and enterprise characteristics, such as entrepreneurial attitude, venture size, and a variety of services offered to customers, on the experienced and expected growth of NBT enterprise. The survey data on NBT enterprises were analyzed with ordered and binary logit models. The willingness of enterprises to participate in LRVT depended on the venture size, entrepreneurial attitude, and type of activities offered to customers. The results show that relatively young and small-sized enterprises have faced difficulties in developing their business. Entrepreneurial experience, risk-taking and intention to develop new business associate positively with expected increase in turnover.

  • Kosenius, University of Helsinki, Department of Economics and Management, P.O. Box 27, FI-00014 University of Helsinki, Finland ORCID ID: https://orcid.org/0000-0002-1528-8145 E-mail: anna-kaisa.kosenius@helsinki.fi (email)
  • Juutinen, Natural Resources Institute Finland (Luke), Bioeconomy and environment, Paavo Havaksentie 3, FI-90570 Oulu, Finland ORCID ID: https://orcid.org/0000-0003-4300-5365 E-mail: artti.juutinen@luke.fi
  • Tyrväinen, Natural Resources Institute Finland (Luke), Bioeconomy and environment, Latokartanonkaari 9, FI-00790 Helsinki, Finland ORCID ID: https://orcid.org/0000-0001-9941-8228 E-mail: liisa.tyrvainen@luke.fi

Category: Review article

article id 10172, category Review article
Ulf Sikström, Karin Hjelm, Kjersti Holt Hanssen, Timo Saksa, Kristina Wallertz. (2020). Influence of mechanical site preparation on regeneration success of planted conifers in clearcuts in Fennoscandia – a review. Silva Fennica vol. 54 no. 2 article id 10172. https://doi.org/10.14214/sf.10172
Highlights: Mechanical site preparation (MSP) increases seedling survival rates by 15–20%; Survival rates of 80–90% ca. 10 years after MSP and planting conifers are possible; MSP can increase tree height 10–15 years after planting by 10–25%; The increase in growth rate associated with MSP may be temporary, but the height enhancement probably persists.

In the Nordic countries Finland, Norway and Sweden, the most common regeneration method is planting after clearcutting and, often, mechanical site preparation (MSP). The main focus of this study is to review quantitative effects that have been reported for the five main MSP methods in terms of survival and growth of manually planted coniferous seedlings of Norway spruce (Picea abies (L.) Karst.), Scots pine (Pinus sylvestris L.) and lodgepole pine (Pinus contorta var. latifolia Engelm.) in clearcuts in these three countries. Meta analyses are used to compare the effects of MSP methods to control areas where there was no MSP and identify any relationships with temperature sum and number of years after planting. In addition, the area of disturbed soil surface and the emergence of naturally regenerated seedlings are evaluated. The MSP methods considered are patch scarification, disc trenching, mounding, soil inversion and ploughing. Studies performed at sites with predominately mineral soils (with an organic topsoil no thicker than 0.30 m), in boreal, nemo-boreal and nemoral vegetation zones in the three Fenno-Scandinavian countries are included in the review. Data from 26 experimental and five survey studies in total were compiled and evaluated. The results show that survival rates of planted conifers at sites where seedlings are not strongly affected by pine weevil (Hylobius abietis L.) are generally 80–90% after MSP, and 15–20 percent units higher than after planting in non-prepared sites. The experimental data indicated that soil inversion and potentially ploughing (few studies) give marginally greater rates than the other methods in this respect. The effects of MSP on survival seem to be independent of the temperature sum. Below 800 degree days, however, the reported survival rates are more variable. MSP generally results in trees 10–25% taller 10–15 years after planting compared to no MSP. The strength of the growth effect appears to be inversely related to the temperature sum. The compiled data may assist in the design, evaluation and comparison of possible regeneration chains, i.e. analyses of the efficiency and cost-effectiveness of multiple combinations of reforestation measures.

  • Sikström, Skogforsk, Uppsala Science Park, SE-751 83 Uppsala, Sweden ORCID ID:E-mail: ulf.sikstrom@skogforsk.se
  • Hjelm, Skogforsk, Ekebo 2250, SE-268 90 Svalöv, Sweden ORCID ID:E-mail: karin.hjelm@skogforsk.se (email)
  • Holt Hanssen, Norwegian Institute of Bioeconomy Research (NIBIO), P.O. Box 115, NO-1431 Ås, Norway ORCID ID:E-mail: kjersti.hanssen@nibio.no
  • Saksa, Natural Resources Institute Finland (Luke), Juntintie 154, FI-77600 Suonenjoki, Finland ORCID ID:E-mail: timo.saksa@luke.fi
  • Wallertz, Swedish University of Agricultural Sciences (SLU), Asa Forest Research Station, SE-360 30 Lammhult, Sweden ORCID ID:E-mail: kristina.wallertz@slu.se

Category: Research note

article id 10263, category Research note
Paul N. Katjutin, Natalia I. Stavrova, Vadim V. Gorshkov, Andrew Yu. Lyanguzov, Irina Ju. Bakkal, Sergey A. Mikhailov. (2020). Radial growth of trees differing in their vitality in the middle-aged Scots pine forests in the Kola peninsula. Silva Fennica vol. 54 no. 3 article id 10263. https://doi.org/10.14214/sf.10263
Highlights: Unmanaged middle-aged boreal Scots pine forests in the Kola peninsula are characterised by the prevalence of moderately and strongly weakened trees (65–70%); Radial increment and basal area increment differ greatly (70–75% and 85–90%, respectively) between Scots pine trees differing in their vitality; The trends of annual ring width in Scots pine trees aged from 15–35 to 65–85 years in green moss and green moss-lichen type pine forests are similar; the dynamics of basal area increment differs substantially in relation to forest site type.

The research was carried out in unmanaged middle-aged (75–85 years) Northern taiga Scots pine (Pinus sylvestris L.) forests in the Kola peninsula. It was established that forests of green moss-lichen and green moss site types are characterised by a predominance (65–70% by stand volume) of moderately and strongly weakened trees. Trees of differing vitality have significant differences in annual increment. Healthy trees had a radial increment (RI) 70–75% greater than that of dying trees, and a basal area increment (BAI) 85–90% greater. The dynamics of the RI and BAI of Scots pine trees for the 70-year period (from 1945 to 2015) is different. The RI of all individuals in the communities studied decreases consistently. The decrease is expressed more strongly in green moss Scots pine forests (80–95% from 1945 to 2015) compared to green moss-lichen forests (60–80%); it manifests itself more in strongly weakened and dying individuals (75–95%) than in healthy and moderately weakened ones (60–80%). Annual basal area increment in green moss Scots pine forests increases by 45–65% from stand establishment until the trees are 25 to 35 years old and subsequently decreases by 50–80% to 70–80 years of age. In green moss-lichen pine forests the BAI of Scots pine remains rather stable in healthy and moderately weakened trees and decreases in strongly weakened and dying individuals by 45% and 75–80%, respectively throughout the studied period.

  • Katjutin, Komarov Botanical Institute of the Russian Academy of Sciences, Professora Popova str. 2, 197376, Saint-Petersburg, Russia ORCID ID:E-mail: paurussia@binran.ru (email)
  • Stavrova, Komarov Botanical Institute of the Russian Academy of Sciences, Professora Popova str. 2, 197376, Saint-Petersburg, Russia ORCID ID:E-mail: nstavrova@binran.ru
  • Gorshkov, Komarov Botanical Institute of the Russian Academy of Sciences, Professora Popova str. 2, 197376, Saint-Petersburg, Russia; Saint-Petersburg State Forest Technical University, letter U, 5, Institutsky per., 194021, Saint-Petersburg, Russia ORCID ID:E-mail: vgorshkov@binran.ru
  • Lyanguzov, Saint-Petersburg State University, 7/9 Universitetskaya Emb., 199034, Saint-Petersburg, Russia ORCID ID:E-mail: andrewlyanguzov@gmail.com
  • Bakkal, Komarov Botanical Institute of the Russian Academy of Sciences, Professora Popova str. 2, 197376, Saint-Petersburg, Russia ORCID ID:E-mail: bakkal@binran.ru
  • Mikhailov, Komarov Botanical Institute of the Russian Academy of Sciences, Professora Popova str. 2, 197376, Saint-Petersburg, Russia ORCID ID:E-mail: smikhailov@binran.ru
article id 10262, category Research note
Markus Melin, Heli Viiri, Olli-Pekka Tikkanen, Riku Elfving, Seppo Neuvonen. (2020). From a rare inhabitant into a potential pest – status of the nun moth in Finland based on pheromone trapping. Silva Fennica vol. 54 no. 1 article id 10262. https://doi.org/10.14214/sf.10262
Highlights: The nun moth is a significant defoliator of coniferous forests in Central-Europe; In Finland, the populations have grown and expanded northwards; Pheromone trapping confirmed the species’ presence throughout central- and southern Finland; The risk of the nun moth becoming a pest for Finland is real as the area offers endless habitats, and climatic conditions are becoming more favourable; This note describes the results from the first nun moth surveys conducted in 2018 and 2019.

Forests are affected by climate change in various ways. This includes abiotic factors such as droughts, but also biotic damage by pest insects. There are numerous examples from cases where pest insects have benefitted from longer growing seasons or from warmer summers. Similarly, new pest insects have been able to expand their range due to climatic conditions that have changed from hostile to tolerable. Such seems to be the case with the nun moth (Lymantria monacha), an important defoliator of coniferous trees in Europe. For centuries, the species has had massive outbreaks across Central-Europe, while it has been a rare inhabitant in Northern Europe. Recently, the nun moth population in Finland has not only expanded in range, but also grown more abundant. This research note describes the results from the first years (2018–2019) of a monitoring program that is being conducted with pheromone traps across central and southern Finland. So far, the northernmost individuals were trapped near the 64 N degrees. However, there were more southern locations where no moths were trapped. The species was present in every trapping site below the latitude of 62 N degrees. More importantly, at some sites the abundance of the nun moth suggested that local forest damage may already occur. Given the current climatic scenarios for Fennoscandia, it is likely that the nun moth populations will continue to grow, which is why systematic surveys on their abundance and range expansions will be topical.

  • Melin, Natural Resources Institute Finland, Yliopistokatu 6b, FI-80100 Joensuu, Finland ORCID ID: https://orcid.org/0000-0001-7290-9203 E-mail: markus.melin@luke.fi (email)
  • Viiri, Natural Resources Institute Finland, Yliopistokatu 6b, FI-80100 Joensuu, Finland; UPM-Kymmene Oyj, UPM Forest, Åkerlundinkatu 11 B, FI-33100 Tampere, Finland ORCID ID:E-mail: heli.viiri@upm.com
  • Tikkanen, University of Eastern Finland, School of Forest Sciences, Yliopistokatu 6, FI-80100 Joensuu, Finland ORCID ID:E-mail: olli-pekka.tikkanen@uef.fi
  • Elfving, Natural Resources Institute Finland, Yliopistokatu 6b, FI-80100 Joensuu, Finland; University of Oulu, Department of Biology, Pentti Kaiteran katu 1, FI-90014 Oulu, Finland ORCID ID:E-mail: riku.elfving@gmail.com
  • Neuvonen, University of Turku, Biodiversity Unit, Kevo Subarctic Research Institute, FI-20014 Turku, Finland ORCID ID:E-mail: seppo.neuvonen@utu.fi

Category: Discussion article

article id 10350, category Discussion article
Maja Peteh. (2020). A synthesis of the characteristics of current national, regional and international forestry journals. Silva Fennica vol. 54 no. 3 article id 10350. https://doi.org/10.14214/sf.10350
Highlights: Currently, 451 forestry-related journals are published worldwide (41.7% in Europe, 37.3% in Asia) in 32 different languages (47.9% in English only); 6 categories have been defined for the geographical coverage of a journal (55.5% of which have been defined as national and 18.2% as international); The journals could increase their visibility and value by improving their websites and submitting relevant information to international indexing databases.

One of the main objectives of the International Union of Forest Research Organization’s WP 9.01.06 (Forest Science Publishing) is to clarify the range of forestry-related journals in the context of the overall objective of supporting authors and readers to deepen their knowledge of forestry. This study extended an earlier list of forestry journals using the ISSN database and the CAB abstracts. The study included 451 journal titles, each categorized by ISSN, publisher, language of publication, website, and geographical coverage (i.e. national, regional, international, or three mixed intermediate categories), as well as information on indexing in Web of Science, Scopus, DOAJ, and SherpaRomeo. The included journals are published in 61 countries and in 32 different languages. Those categorized as international are mostly published in English. 21.7% of the journals are indexed in Web of Science and 34.1% in Scopus. 95.6% of the titles are published online or in the print+online publishing model, but only 57.0% of the titles are published in Open Access, of which only 33.7% are indexed in DOAJ.

  • Peteh, University of Ljubljana, Biotechnical Faculty, Večna pot 83, Ljubljana 1000, Slovenia; Slovenian Forestry Institute, Večna pot 2, Ljubljana 1000, Slovenia ORCID ID: https://orcid.org/0000-0002-9636-1155 E-mail: maja.peteh@gozdis.si (email)

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