Search

Tree species are known to predominantly interact either with arbuscular mycorrhizal (AM) or ectomycorrhizal (EM) fungi. However, there is a knowledge gap regarding whether these mycorrhizae differently influence biodiversity–ecosystem functioning (BEF) relationships and whether a combination of both can increase community productivity. In 2015, we established a tree‐diversity experiment by growing tree communities with varying species richness levels (one, two, or four species) and either with AM or EM tree species or a combination of both. We investigated basal area and annual basal area increment from 2015 to 2020 as proxies for community productivity. We found significant positive relationships between tree species richness and community productivity, which strengthened over time. Further, AM and EM tree species differently influenced productivity; however, there was no overyielding when AM and EM trees grew together. EM tree communities were characterized by low productivity in the beginning but an increase of increment over time and showed overall strong biodiversity effects. For AM tree communities the opposite was true. Although young trees did not benefit from the presence of the other mycorrhizal type, dissimilar mechanisms underlying BEF relationships in AM and EM trees indicate that maximizing tree and mycorrhizal diversity may increase ecosystem functioning in the long run. [ABSTRACT FROM AUTHOR]

Understanding factors that maintain ecosystem stability is critical in the face of environmental change. Experiments simulating species loss from grassland have shown that losing biodiversity decreases ecosystem stability. However, as the originally sown experimental communities with reduced biodiversity develop, plant evolutionary processes or the assembly of interacting soil organisms may allow ecosystems to increase stability over time. We explored such effects in a long‐term grassland biodiversity experiment with plant communities with either a history of co‐occurrence (selected communities) or no such history (naïve communities) over a 4‐yr period in which a major flood disturbance occurred. Comparing communities of identical species composition, we found that selected communities had temporally more stable biomass than naïve communities, especially at low species richness. Furthermore, selected communities showed greater biomass recovery after flooding, resulting in more stable post‐flood productivity. In contrast to a previous study, the positive diversity–stability relationship was maintained after the flooding. Our results were consistent across three soil treatments simulating the presence or absence of co‐selected microbial communities. We suggest that prolonged exposure of plant populations to a particular community context and abiotic site conditions can increase ecosystem temporal stability and resilience due to short‐term evolution. A history of co‐occurrence can in part compensate for species loss, as can high plant diversity in part compensate for the missing opportunity of such adaptive adjustments. [ABSTRACT FROM AUTHOR]