Co‐occurrence history increases ecosystem stability and resilience in experimental plant communities

Abstract

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.

Effects of plant community history, soil legacy and plant diversity on soil microbial communities

“…Here, we found that 4 years of soil microbial community re-assembly under identical plant species compositions was not enough to remove the strong soil legacy effect that had developed under these same plant species compositions for 8 years previous to the experiment. The differences between soil treatments were even maintained through a severe natural flood at the field site in spring 2013 (van Moorsel et al, 2020); during which the plots were completely submerged by standing water. We found much faster adjustments of rhizosphere microbiomes in an associated experiment with the same soil legacy from the Jena Experiment (M.…”

“…In contrast to the strong effects of soil legacy on soil microbial communities, effects of plant community history were much weaker. This was unexpected because those same plant community history treatments led to significant plant evolutionary responses, including changes in plant–plant interactions (Zuppinger-Dingley et al, 2014; van Moorsel et al, 2018 and 2020) and even altered plant–soil feedbacks (Hahl et al, 2020; Zuppinger-Dingley et al, 2016). These evolutionary changes in the plant communities may have been too small to become influential on the diversity and composition of soil microbial communities that may need more time to develop or are too subtle to detect.…”

“…Effects of plant evolution on microbial communities so far are mainly being studied in model plants and for microbiomes directly associated with plants root or leaves (Bergelson et al, 2019;Thiergart et al, 2020). We believe that the importance of the co-evolution between plants and their associated microbial communities in natural plant and soil communities is worthwhile investigating because they may both affect the maintenance of biodiversity in an ecosystem and the resulting effects of biodiversity on ecosystem functioning (van Moorsel et al, 2018(van Moorsel et al, , 2020.…”

Evolution of species complementarity in response to drought in a grassland biodiversity experiment

“…Extreme climatic events such as droughts are predicted to be more frequent in the future 1,2 , with potentially negative effects on the functioning of ecosystems and the provision of ecosystem services for human well-being [3][4][5][6][7] . Ecosystems may adjust to climatic extremes by changes in species abundances [8][9][10] or evolutionary responses of populations [11][12][13][14][15][16][17][18][19] . Both experimental and observational studies have shown that higher biodiversity buffers temporal variation in ecosystem functioning against extreme climatic events 20-24 .…”

“…We used the biomass difference between 2-species mixtures vs. monocultures to calculate the net biodiversity effects, which we further partitioned into complementarity effects (indicating niche differentiation or facilitation) and sampling effects (indicating a disproportionate contribution to community productivity of one or the two species; which is also referred as "selection effect" elsewhere, a term we did not use in this study to avoid confusion) 48 . Second, we assessed the effects of drought selection on resistance (biomass ratio during vs. before the drought), recovery (biomass ratio after vs. during the drought) and resilience (biomass ratio after vs. before the drought) of productivity 19,20 . Third, we tested whether altered plant interactions drove the above differences between the two selection treatments.…”