Search

Resource-use complementarity of producer species is often invoked to explain the generally positive diversity-productivity relationships. Additionally, multi-trophic interactions that link processes across trophic levels have received increasing attention as a possible key driver. Given that both are integral to natural ecosystems, their interactive effect should be evident but has remained hidden. We address this issue by analysing diversity-productivity relationships in a simulation experiment of producer communities nested within complex food-webs, manipulating resource-use complementarity and multi-trophic animal richness. We show that these two mechanisms interactively create diverse communities of complementary producer species. This shapes diversity-productivity relationships such that their joint contribution generally exceeds their individual effects. Specifically, multi-trophic interactions in animal-rich ecosystems facilitate producer coexistence by preventing competitive exclusion despite overlaps in resource-use, which increases the realised complementarity. The interdependence of food-webs and producer complementarity in creating biodiversity-productivity relationships highlights the importance to adopt a multi-trophic perspective on biodiversity-ecosystem functioning relationships.

Aims Ecological theories predict that assembly processes shape communities so that co‐existing species may either be functionally more dissimilar ("divergence") or more similar ("convergence") than expected by chance. Two important factors that are rarely considered in combination are spatial scale and successional stage. Our aim is to identify different functional patterns during succession across spatial scales and to discuss the likely underlying assembly processes. We expect to find convergence due to environmental filtering at early succession, especially at the largest scales, and a tendency towards divergence driven by competitive interactions as succession unfolds and at smaller spatial scales. Location Protected Landscape Area “Bohemian Karst”, Czech Republic. Methods We studied three succession stages (two, eight and 55 years after abandonment). Each field was sampled using 40 1‐m2 quadrats containing 100 pins in a regular grid. We analysed trait dispersion at several combinations of grain and extent and characterised trait similarity using phylogeny and four traits: specific leaf area, leaf dry matter content, height, and seed mass analysed individually and combined using Gower distance (multi‐trait dissimilarity). Results In the youngest field, three of the traits individually and the multi‐trait dissimilarity showed convergence regardless of scale. Phylogeny showed convergence at most spatial scales of the youngest stage. The other two fields showed greater divergence predominantly in the oldest field at the smallest spatial scale. Conclusions The results are mainly congruent with theoretical expectations and provide a valuable example of directional changes from trait convergence to divergence along succession. The scale‐invariant convergence in the early stages of succession seems to be the result of environmental filtering and weaker competitive exclusion. At later stages and particularly at smaller scales, divergence becomes more common, likely because competition limits the trait similarity of species. These results highlight the importance of predictable (non‐random) changes in ecological succession.

While mature forests are declining worldwide, tree plantations could provide habitats of conservation value for forest-adapted species. However, to what degree the fauna in tree plantations matches the diversity and composition of mature forest communities is still debated. In this meta-analysis, we used beetle species (Coleoptera) as biodiversity indicators to assess the conservation value (i.e. the log response ratio in species richness and abundance and the Soerensen similarity) of tree plantations versus reference old-growth forests. We tested the effects of biome, plantation age, tree species richness and origin, surrounding habitat and the trophic position of the focal guild on the diversity and composition of beetle communities. Our results showed that tree plantations generally harboured communities with 47% less individuals, 33% less species and a significantly distinct composition than old-growth forests. In the case that tree plantations had a similar number of species or individuals as old-growth forests, those plantations still displayed a 40% difference in species composition. Beetle abundance was significantly lower in tropical/subtropical plantations and for detrivorous species. We found no further significant drivers of beetle diversity and community composition in tree plantations. We conclude that, although tree plantations can provide crucial habitats for forest-adapted species, they generally harbour less diverse and significantly different communities, highlighting the conservation value of old-growth forests as biodiversity refuges. To properly assess the conservation value of plantations in different taxa, we propose the use of species composition instead of single diversity indices.