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Articles containing the keyword 'habitat'

Category : Article

article id 5637, category Article
Janne Uuttera, Harri Hyppänen. (1997). Relationship between forest management planning units and spatial distribution of forest habitat components in Koli National Park. Silva Fennica vol. 31 no. 4 article id 5637. https://doi.org/10.14214/sf.a8539
Keywords: Finland; forest management planning; forest habitat distribution; Geographic Information Systems; kriging-interpolation; Koli National park
Abstract | View details | Full text in PDF | Author Info

This study examined the relationships between forest management planning units and patches formed by forest habitat components. The test area used was a part of Koli National Park in North Karelia, eastern Finland. Forest management planning units (i.e. forest compartments) were defined by using a traditional method of Finnish forestry which applies aerial photographs and compartment-wise field inventory. Patches of forest habitat components were divided according to subjective rules by using a chosen set of variables depicting the edaphic features and vegetation of a forest habitat. The spatial distribution of the habitat components was estimated with the kriging-interpolation based on systematically located sample plots. The comparisons of the two patch mosaics were made by using the standard tools of GIS. The results of the study show that forest compartment division does not correlate very strongly with the forest habitat pattern. On average, the mean patch size of the forest habitat components is greater and the number of these patches lower compared to forest compartment division. However, if the forest habitat component distribution had been considered, the number of the forest compartments would have at least doubled after intersection.

  • Uuttera, E-mail: ju@mm.unknown (email)
  • Hyppänen, E-mail: hh@mm.unknown
article id 5499, category Article
Niels Elers Koch. (1993). Outlines of environmental policy concerning forests in the European Community. Silva Fennica vol. 27 no. 1 article id 5499. https://doi.org/10.14214/sf.a15660
Keywords: forest policy; forestry; European Community; EC; Forestry Action Programme; environmental policy; forestry strategy; conservation of habitats
Abstract | View details | Full text in PDF | Author Info

The paper, presented at the seminar ”Forestry in Europe: Implications of European Integration for National Forestry”, discusses the effects of first Forestry Action Programme in the European Community, UNCED 1992, the European Community’s new Forestry Strategy and the second Forestry Action Programme directives of conservation of habitats on forestry within the EC.

  • Koch, E-mail: nk@mm.unknown (email)
article id 5190, category Article
Jussi Kuusipalo. (1983). Mustikan varvuston biomassamäärän vaihtelusta erilaisissa metsiköissä. Silva Fennica vol. 17 no. 3 article id 5190. https://doi.org/10.14214/sf.a15173
English title: The distribution of blueberry biomass in different forest stands.
Original keywords: kuusi; metsätyyppi; kasvupaikka; pintakasvillisuus; aluskasvillisuus; biomassa; peittävyys; mustikka; varjostus; puulajisuhteet
English keywords: biomass; Norway spruce; habitat; distribution; shading; ground vegetation; Vaccinium myrtillus; forest types; blueberry
Abstract | View details | Full text in PDF | Author Info

The study deals with the distribution of above-ground biomass of Vaccinium myrtillus L. along the vegetation continuum segregated by using phytosociological classification method composite clustering. The qualitative characteristics of forest sites corresponding to different vegetational clusters were defined on the basis of indirect gradient analysis of vegetation data and description of tree stand properties in stands in 160 sample areas in Southern Finland.

Six vegetation types differing from each other mainly in abundance of the most constant and dominant plant species were formed. Sample areas with rich grass-herb vegetation, as well as sample areas representing comparatively dry, barren site type were clearly separated from other groups of sample areas. Stand characteristics, particularly the proportional distribution of Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) H. Karst.) seems to be another important factor affecting the vegetation composition.

The lowest biomass values of blueberry were connected with herb-rich vegetation and shady spruce-dominated stands. Comparatively low values were connected to also other spruce-dominated sample areas. Pine-dominant or mixed pine-spruce stands the biomass values were significantly higher. Even if the site quality is essentially equal, the abundance relationships between Vaccinium myrtillus and other components of the ground vegetation may vary in wide ranges and cause difficulties in practical site classification.

The PDF includes a summary in English.

  • Kuusipalo, E-mail: jk@mm.unknown (email)

Category : Article

article id 7062, category Article
Aimo Kaarlo Cajander. (1922). Determining concepts for topography of plants. Acta Forestalia Fennica vol. 20 no. 2 article id 7062. https://doi.org/10.14214/aff.7062
Keywords: habitat; vegetation condition; concept; plant topography
Abstract | View details | Full text in PDF | Author Info

The article presents definitions for central concepts that are commonly used in the research of plant topography. The discipline has close connections to defining and classifying forest types.

The concepts defined involve concrete and abstract concepts linked to vegetation conditions and to habitat. 

  • Cajander, E-mail: ac@mm.unknown (email)

Category : Research article

article id 9968, category Research article
Hubert Lachowicz, Anna Bieniasz, Rafał Wojtan. (2019). Variability in the basic density of silver birch wood in Poland. Silva Fennica vol. 53 no. 1 article id 9968. https://doi.org/10.14214/sf.9968
Keywords: Betula pendula; tree age; forest habitat type; thickness of trees; geographical location; physical properties of wood
Highlights: Location, tree age and forest habitat type, and the interactions between those factors, have a statistically significant impact on the basic density of silver birch wood; The average basic density of silver birch wood increases with the age of the tree.
Abstract | Full text in HTML | Full text in PDF | Author Info

This work presents the findings of a study concerning variability in the basic density of silver birch (Betula pendula Roth) wood, depending on the geographical location of tree stands, the age and thickness of the trees, the forest habitat type, and interactions between some of these factors. The study was carried out on wood from trees aged approximately 30, 50 and 70 years in 12 forest districts located throughout Poland. In total 4777 wood samples, taken from 306 trees from 51 test plots, were measured. The location, the age of the trees, the thickness of the trees and the forest habitat type, as well as interactions between these factors, proved to have a significant influence on the basic density of silver birch wood. The highest mean values of the basic density of the birch wood were found in Sokołów forest district on the FBF habitat type (549 kg m–3) and in Giżycko forest district on the FMBF habitat type (548 kg m–3). For the entire set of examined material, the average values of the basic density of wood increase with tree age. For the examined material originating in FBF and FMBF habitats the average values of basic density showed no significant differences; however, in the cases of the forest districts of Giżycko, Łobez and Rudziniec, significant differences in the analysed property were observed.

  • Lachowicz, Department of Forest Utilization, Warsaw University of Life Sciences SGGW, Nowoursynowska 159 02-787 Warsaw, Poland E-mail: hubert.lachowicz@wl.sggw.pl
  • Bieniasz, Department of Forest Utilization, Warsaw University of Life Sciences SGGW, Nowoursynowska 159 02-787 Warsaw, Poland E-mail: anna.bieniasz@wl.sggw.pl (email)
  • Wojtan, Laboratory of Dendrometry and Forest Productivity, Warsaw University of Life Sciences SGGW, Nowoursynowska 159 02-787 Warsaw, Poland E-mail: rwojtan@wl.sggw.pl
article id 9918, category Research article
Ari Nikula, Vesa Nivala, Juho Matala, Kari Heliövaara. (2019). Modelling the effect of habitat composition and roads on the occurrence and number of moose damage at multiple scales. Silva Fennica vol. 53 no. 1 article id 9918. https://doi.org/10.14214/sf.9918
Keywords: forestry; Alces alces; damage probability; forest damage; forest plantation; habitat selection; habitat modelling; zero-inflated negative binomial distribution
Highlights: The occurrence and number of moose damage were modelled with a zero-inflated count model; An admixture of mature forests within plantations increased the number of damage; Vicinity of inhabited areas and roads reduced damage; Plantations in landscapes with a large amount of pine-dominated thinning forests had less damage in Lapland; Damage risk assessment should include characteristics specific to each region.
Abstract | Full text in HTML | Full text in PDF | Author Info

We modelled the effect of habitat composition and roads on the number and occurrence of moose (Alces alces L.) damage in Ostrobothnia and Lapland using a zero-inflated count model. Models were developed for 1 km2, 25 km2 and 100 km2 landscapes consisting of equilateral rectangular grid cells. Count models predict the number of damage, i.e. the number of plantations and zero models the probability of a landscape being without damage for a given habitat composition. The number of moose damage in neighboring grid cells was a significant predictor in all models. The proportion of mature forest was the most frequent significant variable, and an increasing admixture of mature forests among plantations increased the number and occurrence of damage. The amount of all types of plantations was the second most common significant variable predicting increasing damage along with increasing amount of plantations. An increase in thinning forests as an admixture also increased damage in 1 km2 landscapes in both areas, whereas an increase in pine-dominated thinning forests in Lapland reduced the number of damage in 25 km2 landscapes. An increasing amount of inhabited areas in Ostrobothnia and the length of connecting roads in Lapland reduced the number of damage in 1 and 25 km2 landscapes. Differences in model variables between areas suggest that models of moose damage risk should be adjusted according to characteristics that are specific to the study area.

  • Nikula, Natural Resources Institute Finland (Luke), Bioeconomy and Environment, Ounasjoentie 6, FI-96200 Rovaniemi, Finland E-mail: ari.nikula@luke.fi (email)
  • Nivala, Natural Resources Institute Finland (Luke), Bioeconomy and Environment, Ounasjoentie 6, FI-96200 Rovaniemi, Finland E-mail: vesa.nivala@luke.fi
  • Matala, Natural Resources Institute Finland (Luke), Natural resources, Yliopistokatu 6, FI-80100 Joensuu, Finland E-mail: juho.matala@luke.fi
  • Heliövaara, University of Helsinki, Department of Forest Sciences, P.O. Box 27, FI-00014 University of Helsinki, Finland E-mail: kari.heliovaara@helsinki.fi
article id 7699, category Research article
Dalytė Matulevičiūtė, Jurga Motiejunaite, Domas Uogintas, Ričardas Taraškevičius, Mindaugas Dagys, Valerijus Rašomavičius. (2018). Decline of a protected coastal pine forest under impact of a colony of great cormorants and the rate of vegetation change under ornithogenic influence. Silva Fennica vol. 52 no. 2 article id 7699. https://doi.org/10.14214/sf.7699
Keywords: coniferous forests; piscivorous birds; Baltic Sea; habitats
Highlights: We studied vegetation and its changes in a pine forest affected by a colony of great cormorants; Vegetation in the colony varied according to the period of bird influence and the stand elevation above sea level; Considerable vegetation changes occur in several years after bird colony establishment; Pine forest ecosystem cease to exist following a decade of bird activity.
Abstract | Full text in HTML | Full text in PDF | Author Info

We investigated the impact of a colony of great cormorants on the vegetation of the old growth Pinus sylvestris L. forest on the Curonian Spit peninsula, Lithuania. We studied the characteristics and rates of plant cover changes under varying length and intensity of bird influence. Plant species numbers, as well as the coverage of plants with different ecological requirements, varied according to the period of bird influence, but the resulting vegetation also depended upon the stand elevation above sea level. In our study, the initial increase in plant species richness at the start of bird nesting was not obvious and was of a transient character, due to the weak invasion of non-forest species and the rapid decline of forest plants. The colony area showed obvious and rapid vegetation changes during the investigation period. According to the calculated colony expansion rates, after 6–7 years of impact from birds the tree layer decreased by about four fold; the shrub layer decreased by about two fold; the field layer decreased by about 15 fold; and the dwarf shrub and bottom layers disappeared. The coverage by oligotrophic species decreased by more than four fold, while the coverage by eutrophic species increased by more than 60 fold. After 9–10 years of ornithogenic impact, all the trees were dead, and the protected coniferous forest ecosystem, with its characteristic plant species, had ceased to exist as such.

  • Matulevičiūtė, Institute of Botany, Nature Research Centre, Žaliųjų ežerų Str. 49, LT-08406 Vilnius, Lithuania ORCID http://orcid.org/0000-0001-7550-1860 E-mail: dalyte.matuleviciute@botanika.lt (email)
  • Motiejunaite, Institute of Botany, Nature Research Centre, Žaliųjų ežerų Str. 49, LT-08406 Vilnius, Lithuania ORCID http://orcid.org/0000-0002-6949-1990 E-mail: jurga.motiejunaite@botanika.lt
  • Uogintas, Institute of Botany, Nature Research Centre, Žaliųjų ežerų Str. 49, LT-08406 Vilnius, Lithuania ORCID http://orcid.org/0000-0002-3937-1218 E-mail: domas.uogintas@botanika.lt
  • Taraškevičius, Geology and Geography Institute, Nature Research Centre, Akademijos Str. 2, LT-08412 Vilnius, Lithuania ORCID http://orcid.org/0000-0002-5110-6142 E-mail: taraskevicius@geo.lt
  • Dagys, Institute of Ecology, Nature Research Centre, Akademijos Str. 2, LT-08412 Vilnius, Lithuania ORCID http://orcid.org/0000-0001-9342-3464 E-mail: dagys@ekoi.lt
  • Rašomavičius, Institute of Botany, Nature Research Centre, Žaliųjų ežerų Str. 49, LT-08406 Vilnius, Lithuania ORCID http://orcid.org/0000-0003-1314-4356 E-mail: valerijus.rasomavicius@botanika.lt
article id 6986, category Research article
Mari Tilk, Tea Tullus, Katri Ots. (2017). Effects of environmental factors on the species richness, composition and community horizontal structure of vascular plants in Scots pine forests on fixed sand dunes. Silva Fennica vol. 51 no. 3 article id 6986. https://doi.org/10.14214/sf.6986
Keywords: biodiversity; inland dunes; microhabitats; soil conditions; vegetation–site relationships
Highlights: Factors affecting the species richness, composition and horizontal structure of vascular plants are related to dune topography, resulting in the differentiation of soils and therefore complexes of different microhabitats that are populated by various vascular plant species and causing vegetation zonation.
Abstract | Full text in HTML | Full text in PDF | Author Info

Different environmental factors were studied to determine which factors influence the species richness, composition and structure of vascular plants in Pinus sylvestris L. forests in a fixed dune landscape in south-western Estonia. In addition to site topographic factors, different environmental parameters were investigated. Thirty-four vascular plant species were recorded in 232 quadrats. The most abundant species was Vaccinium vitis-idaea L., which was in 82.8% of quadrats, followed by Vaccinium myrtillus L. (74.1%), Melampyrum pratense L. (71.1%) and Deschampsia flexuosa (L.) Trin. (69.8%). The multiple response permutation procedure (MRPP) showed considerable differences in species composition at the bottoms of dunes compared with that on the slopes and at the tops of dunes. Indicator species analysis (ISA) determined species exhibited characteristics specific to zone: V. myrtillus had the highest indicator value at the bottoms of dunes; Calluna vulgaris L., at the tops. Soils were Haplic Podzols, and the presence of humus horizon depended on zone. Soil conditions on the dunes were variable and site specific, in general, soils at the bottoms of the dunes were more acidic and moist compared with those of the slopes and tops of the dunes, and the nutrient content decreased toward the dune tops. According to non-metric multidimensional scaling (NMDS) and linear mixed model analyses, species coverage, composition and richness were controlled by site-specific factors such as absolute height, location and aspect of the quadrat on the dune; soil nitrogen, potassium and phosphorus contents; soil pH and moisture; light conditions; and the thickness of the litter horizon.

  • Tilk, Department of Silviculture, Estonian University of Life Sciences, Kreutzwaldi 5, Tartu, Estonia, 51014; Tallinn Botanic Garden, Kloostrimetsa Road 52, Tallinn, Estonia, 11913 E-mail: Mari.Tilk@botaanikaaed.ee (email)
  • Tullus, Department of Silviculture, Estonian University of Life Sciences, Kreutzwaldi 5, Tartu, Estonia, 51014 E-mail: Tea.Tullus@emu.ee
  • Ots, Department of Silviculture, Estonian University of Life Sciences, Kreutzwaldi 5, Tartu, Estonia, 51014 E-mail: Katri.Ots@emu.ee
article id 1516, category Research article
Hamed Yousefzadeh, Abasalt Hosseinzadeh Colagar, Fatemeh Fallah. (2016). Genetic diversity of geographically isolated Iranian populations of Betula pendula Roth: implications for conservation. Silva Fennica vol. 50 no. 3 article id 1516. https://doi.org/10.14214/sf.1516
Keywords: genetic differentiation; habitat isolation; haplotype diversity; genetic drift; long-term isolation
Highlights: The Iranian populations of birches exhibited high levels of genetic diversity, population differentiation, and the presence of unique haplotypes; The high genetic differentiation amongst the populations may contribute to the local geographical structure and poor gene flow amongst individuals; The results can potentially be used to adopt appropriate strategies for the conservation and management of isolated tree populations.
Abstract | Full text in HTML | Full text in PDF | Author Info

The effects of long-term habitat fragmentations on genetic and population differentiation of Betula pendula Roth were investigated using chloroplast DNA (cpDNA) variations. Leaf samples were collected from four small remnant populations across the north of Iran. Three pairs of universal primers were used to amplify cpDNA, large single copy regions of trnC-trnD, trnK1-trnK2 and trnD-trnT. A total of 18 of the cpDNA haplotypes in the four populations were identified, however, no clear phylogeographic structuring of haplotypes could be detected. The total genetic diversity (HT) for all populations was high (0.932). Average intra-population genetic diversity was estimated as HS = 0.729 and average differentiation of populations GST = 0.218. Mantel tests of isolation by distance revealed a significant relationship between Wright’s inbreeding coefficient (Fst) and geographical distances for the four populations in Iran (r = 0.77, p < 0.05). The results of the hierarchical analysis of molecular variance (AMOVA) indicated that a 66% variation was partitioned within populations, whilst the variance amongst the four populations was only 34%. We suggest that significant genetic differentiation amongst populations can likely be attributed to reduced gene flow as a result of habitat fragmentation.

  • Yousefzadeh, Department of Forestry, Faculty of Natural Resources, Tarbiat Modares University, Nour, Mazandaran, Iran E-mail: h.yousefzadeh@modares.ac.ir (email)
  • Hosseinzadeh Colagar, Department of Molecular and Cell Biology; Faculty of Basic Sciences, University of Mazandaran, 47416-95447 Babolsar, Iran E-mail: ahcolagar@umz.ac.ir
  • Fallah, Department of Molecular and Cell Biology; Faculty of Basic Sciences, University of Mazandaran, 47416-95447 Babolsar, Iran E-mail: fatemehfalah69@yahoo.com
article id 84, category Research article
Asko Lõhmus, Piret Lõhmus. (2011). Old-forest species: the importance of specific substrata vs. stand continuity in the case of calicioid fungi. Silva Fennica vol. 45 no. 5 article id 84. https://doi.org/10.14214/sf.84
Keywords: forest management; conservation; continuity; habitat; lichen; limiting factor; structural diversity
Abstract | View details | Full text in PDF | Author Info
Appropriate conservation management of old-forest species depends on the causes of their old-forest affinity, which, however, are insufficiently known. Calicioid fungi are often considered old-forest dependent because of their special requirements for microhabitat, microclimate, and stand continuity for at least two tree generations. We demonstrate that, for several methodological or interpretational problems, published studies do not provide unequivocal evidence for such mechanisms and even for old-forest dependency of calicioids in general. We then analyse a large Estonian dataset (ca. 2300 records of 32 species) representing various management types and site types to answer whether old forests have more calicioid species, and any specific species, than could be expected for the substratum availability observed. Although old growth had more species and records than mature managed stands or cutover sites, those substratum types that occurred at roughly similar abundances also hosted comparable numbers of species in different management types. The characteristic substrata adding extra species to old growth were snags and root-plates of treefall mounds; wood surfaces in general comprised more than half of all calicioid records. Although substratum abundance did not fully explain the species-richness contrast between old growth and mature stands, additional evidence suggested that the unexplained variance is rather due to small-scale habitat characteristics than stand-scale continuity or microclimate. Finally, we review the evidence for old-forest affinity of calicioid species and distinguish a set of threatened species. We conclude that the availability of specific substrata is the main limiting factor for calicioid fungi in forests, and its quantitative and stochastic nature explains the large random and region-specific variation in the published lists of ‘old-forest species’.
  • Lõhmus, Department of Zoology, Institute of Ecology and Earth Sciences, University of Tartu, Vanemuise st. 46, EE-51014, Tartu, Estonia E-mail: asko.lohmus@ut.ee (email)
  • Lõhmus, Department of Botany, Institute of Ecology and Earth Sciences, University of Tartu, Tartu, Estonia E-mail: pl@nn.ee
article id 80, category Research article
Mari T. Jönsson, Shawn Fraver, Bengt Gunnar Jonsson. (2011). Spatio-temporal variation of coarse woody debris input in woodland key habitats in central Sweden. Silva Fennica vol. 45 no. 5 article id 80. https://doi.org/10.14214/sf.80
Keywords: boreal forest; Picea abies; dendrochronology; disturbance dynamics; tree mortality; woodland key habitats; windstorms
Abstract | View details | Full text in PDF | Author Info
The persistence of many saproxylic (wood-living) species depends on a readily available supply of coarse woody debris (CWD). Most studies of CWD inputs address stand-level patterns, despite the fact that many saproxylic species depend on landscape-level supplies of CWD. In the present study we used dated CWD inputs (tree mortality events) at each of 14 Norway spruce (Picea abies) dominated woodland key habitat sites to analyze the spatial and temporal patterns of CWD additions between 1950 and 2002 within a small landscape in central Sweden. We found that inputs were episodic within sites, where local windstorms created pulses in CWD input. Pulses occurred simultaneously in many sites, yielding landscape-level synchrony of CWD input. These synchronous pulses, and importantly, the breaks between pulses, may have negative implications for saproxylic species that are dependent on large volume inputs of freshly killed Norway spruce. In addition, the inherent small size and relative isolation of these sites may further increase extinction risks due to stochastic events. However, background CWD input rates occurring between pulses varied substantially among sites, presumably the result of the sites’ varied histories and structural characteristics. This finding suggests that the different sites have varied abilities to provide habitat for saproxylic species during periods with low landscape-level input of CWD.
  • Jönsson, Department of Ecology, SLU, P.O. Box 7044, SE-750 07 Uppsala, Sweden (current); Department of Natural Sciences, Engineering and Mathematics, Mid Sweden University, Sundsvall, Sweden E-mail: mari.jonsson@slu.se (email)
  • Fraver, U.S. Forest Service, Northern Research Station, Grand Rapids, Minnesota, USA (current); Department of Natural Sciences, Engineering and Mathematics, Mid Sweden University, Sundsvall, Sweden E-mail: sf@nn.us
  • Jonsson, Department of Natural Sciences, Engineering and Mathematics, Mid Sweden University, Sundsvall, Sweden E-mail: bgj@nn.se
article id 216, category Research article
Juha Siitonen, Jenni Hottola, Auli Immonen. (2009). Differences in stand characteristics between brook-side key habitats and managed forests in southern Finland. Silva Fennica vol. 43 no. 1 article id 216. https://doi.org/10.14214/sf.216
Keywords: dead wood; woodland key habitats; stand structure; CWD; WKH; Forest Act
Abstract | View details | Full text in PDF | Author Info
Preservation of small habitat patches termed as “woodland key habitats” or “especially important habitats” in the Finnish Forest Act has become an integral part of biodiversity-oriented forest management. Forest Act habitats belong to particular habitat types defined in the act, and they are supposed to have natural-like stand characteristics. However, very little is known about the actual stand structure in the designated habitats. Our aim was to compare stand characteristics between brook-side key habitats and comparable managed forests as controls. Seven study areas were selected from four regions across southern Finland. Within each study area ten key habitats and ten controls (140 stands) were randomly selected. Living and dead trees and cut stumps were measured in each stand within a 0.2 ha plot. The average degree of previous cutting was significantly lower whereas the volume of dead wood, volume of deciduous trees, and stand diversity were each significantly higher in key habitats than controls. The average volume of dead wood was 11.7 m3 ha–1 in key habitats and 6.5 m3 ha–1 in controls. However, there was considerable variation among individual stands, and a large part of key habitats could not be distinguished from randomly selected control stands with respect to stand characteristics. The preservation of natural brook channels with their immediate surroundings is undoubtedly important for maintaining aquatic and semiaquatic biodiversity. Nevertheless, when complementing the forest conservation network in the future, main emphasis in selecting potentially valuable stands should be placed on important structural features such as dead wood and old trees.
  • Siitonen, Finnish Forest Research Institute, Vantaa Research Unit, P.O. Box 18, FI-01301 Vantaa, Finland E-mail: juha.siitonen@metla.fi (email)
  • Hottola, Finnish Forest Research Institute, Vantaa Research Unit, P.O. Box 18, FI-01301 Vantaa, Finland E-mail: jh@nn.fi
  • Immonen, Finnish Forest Research Institute, Vantaa Research Unit, P.O. Box 18, FI-01301 Vantaa, Finland E-mail: ai@nn.fi
article id 396, category Research article
Timo Pukkala, Mikko Kurttila. (2005). Examining the performance of six heuristic optimisation techniques in different forest planning problems. Silva Fennica vol. 39 no. 1 article id 396. https://doi.org/10.14214/sf.396
Keywords: genetic algorithms; simulated annealing; ecological planning; habitat suitability index (HSI); Hero; random search; tabu search
Abstract | View details | Full text in PDF | Author Info
The existence of multiple decision-makers and goals, spatial and non-linear forest management objectives and the combinatorial nature of forest planning problems are reasons that support the use of heuristic optimisation algorithms in forest planning instead of the more traditional LP methods. A heuristic is a search algorithm that does not necessarily find the global optimum but it can produce relatively good solutions within reasonable time. The performance of different heuristics may vary depending on the complexity of the planning problem. This study tested six heuristic optimisation techniques in five different, increasingly difficult planning problems. The heuristics were evaluated with respect to the objective function value that the techniques were able to find, and the time they consumed in the optimisation process. The tested optimisation techniques were 1) random ascent (RA), 2) Hero sequential ascent technique (Hero), 3) simulated annealing (SA), 4) a hybrid of SA and Hero (SA+Hero), 5) tabu search (TS) and 6) genetic algorithm (GA). The results, calculated as averages of 100 repeated optimisations, were very similar for all heuristics with respect to the objective function value but the time consumption of the heuristics varied considerably. During the time the slowest techniques (SA or GA) required for convergence, the optimisation could have been repeated about 200 times with the fastest technique (Hero). The SA+Hero and SA techniques found the best solutions for non-spatial planning problems, while GA was the best in the most difficult problems. The results suggest that, especially in spatial planning problems, it is a benefit if the method performs more complicated moves than selecting one of the neighbouring solutions. It may also be beneficial to combine two or more heuristic techniques.
  • Pukkala, University of Joensuu, Faculty of Forestry, P.O. BOX 111, FI-80101 Joensuu, Finland E-mail: timo.pukkala@forest.joensuu.fi (email)
  • Kurttila, Finnish Forest Research Institute, Joensuu Research Centre, P.O. Box 68, FI-80101 Joensuu, Finland E-mail: mk@nn.fi

Category : Review article

article id 390, category Review article
Bengt Gunnar Jonsson, Nicholas Kruys, Thomas Ranius. (2005). Ecology of species living on dead wood – lessons for dead wood management. Silva Fennica vol. 39 no. 2 article id 390. https://doi.org/10.14214/sf.390
Keywords: forest management; saproxylic species; coarse woody debris; woodland key habitats; landscape planning; Fennoscandian forests; epixylic species
Abstract | View details | Full text in PDF | Author Info
Dead wood has been identified as a crucial component for forest biodiversity. Recent research has improved our understanding of habitat relations for many species associated with dead wood. However, the consequences for forest management are yet to be explored. In this review we build upon the growing volume of studies on dead wood dependent species, the dynamics of dead wood and ecological theory in order to identify the challenges for forest management at the landscape level. The review has a Fennoscandian focus, but the problems and challenges are similar in many forest ecosystems. We argue that it is necessary to 1) counteract the current shortage in availability of dead wood, 2) concentrate planning at the landscape level in order to minimize isolation and reduce edge effects, 3) create a variety of dead wood types, and 4) utilise available quantitative analytical tools. This calls for new approaches to management that to a large extent includes available knowledge, and to find platforms for planning forested landscapes with diverse holdings.
  • Jonsson, Mid Sweden University, Dept of Natural Sciences, SE-851 70 Sundsvall, Sweden E-mail: bengt-gunnar.jonsson@miun.se (email)
  • Kruys, SLU, Dept of Forest Resource Management and Geomatics, SE-901 83 Umeå, Sweden E-mail: nk@nn.se
  • Ranius, SLU, Dept of Entomology, SE-750 07 Uppsala, Sweden E-mail: tr@nn.se

Category : Research note

article id 10491, category Research note
Atte Komonen, Ilkka Puumala, Gergely Várkonyi, Reijo Penttilä. (2021). Wood-decaying fungi in old-growth boreal forest fragments: extinctions and colonizations over 20 years. Silva Fennica vol. 55 no. 1 article id 10491. https://doi.org/10.14214/sf.10491
Keywords: polypores; fragmentation; extinction debt; habitat loss; spruce forest
Highlights: Rare fungi can persist for decades in isolated old-growth forest fragments; The remaining old-growth forest fragments should be urgently protected, even if they are isolated from larger expanses of natural biotopes.
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According to ecology theory, isolated habitat fragments cannot maintain populations of specialized species. Yet, empirical evidence based on monitoring of the same fragments over time is still limited. We studied the colonization–extinction dynamics of eight wood-decaying fungal species in 16 old-growth forest fragments (<14 ha) over a 20-year period (1997–2017). We observed 19 extinctions and 5 colonizations; yet, the distribution of extinctions and colonizations did not differ from the one expected by chance for any of the species. Twenty-six percent of the extinctions took place in two natural fragments amid large forest–peatland complexes. Phellinus nigrolimitatus (Romell) Bourdot and Galzin decreased and Phellinus ferrugineofuscus (P. Karst.) Bourdot increased in abundance (number of logs occupied). The volume of living spruce trees in the forest fragments correlated positively with the number of logs inhabited in five of the study species. Because fragment characteristics did not affect species turnover, it seems that stochastic processes governed colonizations and extinctions. Although the least abundant species in 1997 had declined, and the most abundant species had become more abundant, it appears that specialized wood-decaying fungi can persist for decades in isolated old-growth forest fragments, if suitable dead wood is continuously available.

  • Komonen, University of Jyväskylä, Department of Biological and Environmental Science, School of Resource Wisdom, P.O. Box 35, FI-40014 University of Jyväskylä, Finland E-mail: atte.komonen@jyu.fi (email)
  • Puumala, University of Jyväskylä, Department of Biological and Environmental Science, School of Resource Wisdom, P.O. Box 35, FI-40014 University of Jyväskylä, Finland E-mail: ilkka.puumala1@outlook.com
  • Várkonyi, Finnish Environment Institute, Friendship Park Research Centre, Lentiirantie 342 B, FI-88900 Kuhmo, Finland E-mail: gergely.varkonyi@ymparisto.fi
  • Penttilä, Natural Resources Institute Finland, Natural resources, Latokartanonkaari 9, FI-00790 Helsinki, Finland E-mail: reijo.penttila@luke.fi

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