Forest structure and heterogeneity increase diversity and alter composition of host-parasitoid networks

Antagonistic host-parasitoid interactions can be quantified using bipartite and metanetworks, which have the potential to reveal how habitat structural elements relate to this important ecosystem function.Here, we analysed the host-parasitoid interactions of cavity-nesting bees and wasps, as well as their abundance, diversity and species richness with forest structural elements from 127 forest research plots in southwestern Germany.We found that parasitoid abundance, diversity and species richness all increase with host abundance, a potential mediator between parasitoids and forest structure. Both parasitoid abundance and diversity increased with stand structural complexity, possibly mediated by the abundance of hosts. In addition, parasitoid abundance increased with increasing standing deadwood and herb cover.The bipartite networks of host-parasitoid interactions showed higher connectance with increasing standing deadwood, herb cover and host abundance. Analyses of interactions within the host-parasitoid metanetwork revealed that increasing host abundance and decreasing canopy cover diversify the suites of interactions present at the plot level.These results demonstrate that forest structural elements can improve the stability and resilience of host-parasitoid networks by promoting parasitoids and diversifying interactions in ecological networks.Cavity-nesting bees and wasps and their associated parasitoids rely on forest structural elements such as deadwood. Host-parasitoid interaction networks can reveal how these forest structures can support this important ecosystem function.Here, we sample cavity-nesting bee wasps and their parasitoids from 127 forest research sites, along with gradients of amounts of forest structural elements.We found that increasing amounts of forest structural elements increased the diversity of parasitoids and altered species composition, partly via increasing host abundance. In addition, canopy openness diversified suites of host-parasitoid interactions.imag

Where are we now with European forest multi-taxon biodiversity and where can we head to?

International audienceForestry implementation significantly impacts forest biodiversity. Despite the promotion of Sustainable Forest Management (SFM) in Europe, sustainability assessments hardly account for direct biodiversity indicators. We aim to i) gather and map the existing information on forest multitaxon biodiversity associated with stand structure and management in Europe; ii) identify knowledge gaps for forest biodiversity research; and iii) discuss the research potential associated with multitaxon biodiversity data. We established a research network focused on multi-taxon biodiversity, stand structure and management data of European forests; and fitted species records, standing trees, lying deadwood, and sampling unit metadata from 34 local datasets. Suitable information was available for 3,591 sampling units, each surveyed for on average 4.6 taxonomic groups. Standing tree diameters, tree height deadwood and tree-related microhabitats were sampled in respectively 2,889; 2,356; 2,309 and 1,388 sampling units. Sampling unit metadata includes spatial coordinates, and compositional and management descriptors. Available data cover all the 14 European forest compositional categories but are unevenly distributed among them, with European beech forests being over-represented as compared to thermophilous and boreal forests. Overall, the available information has the potential to inform the development of conservation and SFM strategies for European forests by supporting: (i) methodological harmonization and coordinated monitoring; (ii) the definition and testing of SFM indicators and thresholds; (iii) datadriven assessment of the effects of environmental and management drivers on multi-taxon forest biological and functional diversity, (iv) multi-scale forest monitoring integrating in-situ and remotely sensed information