Changes within a single land-use category, forests: threat to biodiversity of saproxylic organisms in terrestrial ecosystems?

Background/Question/Methods

Land-use change is identified as one of the most important drivers affecting biodiversity in terrestrial ecosystems. Beneath land-use change, there are subcategory changes within land-use types e.g. as a result of management. These changes have received far less attention and their effects on biodiversity are less understood, especially for their effects on microbial communities. Forest management activities and with it conversions from one forest type to another potentially modify most characteristics and components of the entire forest ecosystem. We used wood-inhabiting fungi as a model for saproxylic organisms, especially important because of the fungal dominance in wood decay. Specifically, we tested if changes in forest management regimes within beech-dominated forests, and forest type conversion from semi-natural beech to coniferous forest affect wood-inhabiting fungal richness and community structure and composition. We used a culture independent molecular approach based on the length polymorphism in the ribosomal intergenic spacer region (fungal automated ribosomal intergenic spacer analysis (F-ARISA)) to assess fungal operational taxonomic units (OTUs).  This was applied on DNA extractions from deadwood logs of plots in the German Biodiversity Exploratories.     

Results/Conclusions

Overall, 20 – 24% and 25 – 27% of native fungal OTUs from forest reserves and semi-natural forests became undetectable or were lost in managed and converted forests, respectively. Fungal richness was significantly reduced during a regeneration phase in age-class beech forests with a high level of wood extraction (P = 0.017) while fungal community structures and composition were not significantly affected by forest management regimes. Conversion of forests from native, European beech to coniferous species (Norway spruce, Scots pine) caused significant changes in the fungal community structure (P = 0.0001) and composition (P = 0.0001), and could reduce fungal richness and diversity (P < 0.05). We conclude that changes within a single land-use category can be regarded as a major threat to biodiversity of saproxylic organisms in terrestrial ecosystems.