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Abstract: Background A major challenge in biodiversity science is to understand the factors contributing to the variability of species richness –the number of different species in a community or region - among comparable taxonomic lineages. Multiple biotic and abiotic factors have been hypothesized to have an effect on species richness and have been used as its predictors, but identifying accurate predictors is not straightforward. Spiders are a highly diverse group, with some 48,000 species in 120 families; yet nearly 75% of all species are found within just the ten most speciose families. Here we use a Random Forest machine learning algorithm to test the predictive power of different variables hypothesized to affect species richness of spider genera. Results We test the predictive power of 22 variables from spiders’ morphological, genetic, geographic, ecological and behavioral landscapes on species richness of 45 genera selected to represent the phylogenetic and biological breath of Araneae. Among the variables, Random Forest analyses find body size (specifically, minimum male body size) to best predict species richness. Multiple Correspondence analysis confirms this outcome through a negative relationship between male body size and species richness. Multiple Correspondence analyses furthermore establish that geographic distribution of congeneric species is positively associated with genus diversity, and that genera from phylogenetically older lineages are species poorer. Of the spider-specific traits, neither the presence of ballooning behavior, nor sexual size dimorphism, can predict species richness. Conclusions We show that machine learning analyses can be used in deciphering the factors associated with diversity patterns. Since no spider-specific biology could predict species richness, but the biologically universal body size did, we believe these conclusions are worthy of broader biological testing. Future work on other groups of organisms will establish whether the detected associations of species richness with small body size and wide geographic ranges hold more broadly.
Keywords: biodiversity, lineage diversity, species traits, spiders, phylogenetic diversity, species distribution, random forest, multiple correspondence analysis
Published in DiRROS: 22.07.2024; Views: 64; Downloads: 29
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Abstract: Changing environmental conditions, disturbances, and escalating demands for forest ecosystem services require foresters to restore present forestlands with new forest generations that will exhibit ecological integrity, diversity, high adaptive capacity, and the ability to provide essential ecosystem services. Establishing such forests requires careful consideration of the forest landscape and site dynamics. In pursuit of these requirements, we developed a novel framework that enables the restoration of forest sites and promotes the desired features of the forest complex at the same time. This framework was designed with the methods of system engineering and was organized in the same way as the forest planning process. It was tested in the habitat type of Illyrian Fagus sylvatica forests belonging to the Natura 2000 network. The environmental, vegetation, and site conditions were investigated via field inspections, available forest management plans, and simple GIS analyses. Additionally, we established a seminatural stand composed of European beech, sessile oak, sycamore maple, silver fir, and some wild fruit tree species. The survival of planted species was assessed using census and simple random sampling, the performance of provenances by the Student’s test, while microhabitat factors were explored by a one-way ANOVA. The survival rate of key species was estimated to be 55.6%, while that of fruit species was estimated to be 94.5%. Our framework demonstrated satisfactory performance and contained sufficient benchmarks to facilitate consistent decision-making. In the discussion, we elucidate the framework’s primary features and attributes of the mixed stand, where we also expose some open issues to be addressed in the future.
Keywords: restoration, forest habitat type, indigenous species, planting, mixed stand, key species, fruit species
Published in DiRROS: 13.06.2024; Views: 143; Downloads: 94
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Keywords: national forest inventory, history, statistical design
Published in DiRROS: 20.05.2024; Views: 228; Downloads: 306
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Abstract: Private forest ownership, with small and fragmented forest properties prevailing in Europe, is affected by demographic, economic and social changes as well as by forest-related policy goals. This is reflected in the lack of knowledge about forest management, insufficient forest management and underutilization of forest resources. Considering that, business coop- eration between private forest owners and with forest service providers or managers is recog- nized as one of the key instruments to increase the efficiency of private forest management. The aim of this study is to investigate whether there is a potential for further development of forest lease as form of long-term business cooperation. In this research, interviews (n=8) were conducted with tenants who have signed long-term forest lease contracts with private forest owners in Slovenia. The results show that there are limited possibilities for further develop- ment of long-term business cooperation between private forest owners and forest service pro- viders/managers (e.g. forest lease). The results indicate that there are many benefits of long- term business cooperation for both sides, but private forest owners’ interest is questionable. If we want long-term business cooperation (forest lease) to succeed, forest lease should be rec- ognized in legislation, education about business cooperation (forest lease) should be given to public forest service employees, so they could promote forest lease and provide information to private forest owners. In addition, a connection between potential business partners should be established and examples of good practice should be promoted to gain trust between busi- ness partners, which could increase private forest owners’ interest and consequently improve private forest management and utilization of forest resources from private forests.
Keywords: small-scaled private forest owners, business contract, forest lease agreement, snowball sampling
Published in DiRROS: 24.04.2024; Views: 276; Downloads: 102
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Abstract: Forest ground vegetation may serve as an early warning system for monitoring anthropogenic global-change impacts on temperate forests. Climate warming may induce a decline of cool-adapted species to the benefit of more thermophilous plants. Nitrogen deposition has been documented to potentially result in soil eutrophication or acidification, which can increase the proportion of species with higher nutrient requirements and species impoverishment caused by competitive exclusion. Abiotic forest disturbances are changing the light conditions in the forest understorey environment. In this resurvey study, we tested the magnitude and direction of change in alpha (species richness) and beta (within-site dissimilarity) diversity and composition of forest ground vegetation in forests of different types in Slovenia over fifteen years. Using plant-derived characteristics (Ellenberg-type indicator values) and by testing a priori predictions concerning expected effects of environmental drivers, we show that the magnitude and direction of forest ground vegetation diversity and floristic changes varies greatly between forest sites. Divergent responses at different sites resulted in low net change of alpha and beta diversity and a weak overall environmental signal. The largest decrease in species number was observed in lowland oak-hornbeam forests, which were also among the sites with the greatest compositional shifts. Changes in beta diversity did not show any consistent trend, and anticipated floristic convergence was not confirmed when all sites were considered. Thermophilization was mainly detected in montane beech sites and alpine spruce forests whereas eutrophication signal was most significant on nutrient-poor sites. Vegetation responses were strongly dependent on initial site conditions. Shrinkage of ecological gradients (process of ecological homogenization) suggests that sites positioned at the ends of the gradients are losing their original ecological character and are becoming more similar to mid-gradient sites that generally exhibit smaller changes. Our results point to the importance of local stand dynamics and overstorey disturbances in explaining the temporal trends in forest ground vegetation. Ground vegetation in Slovenian forests is changing in directions also dictated by multiple regional and global change drivers.
Keywords: vegetation resurvey, thermophilization, eutrophication, forest disturbances, alpha and beta diversity, initial site conditions, ICP-Forests network
Published in DiRROS: 09.04.2024; Views: 390; Downloads: 182
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