Trophic and non‐trophic interactions influence the mechanisms underlying biodiversity–ecosystem functioning relationships under different abiotic conditions

Abstract

Plant diversity effects on ecosystem functioning usually have been studied from a plant perspective. However, the mechanisms underlying biodiversity–ecosystem functioning relationships may also depend on positive or negative interactions between plants and other biotic and abiotic factors, which remain poorly understood. Here we assessed whether plant–herbivore and/or plant–detritivore interactions modify the biodiversity–ecosystem functioning relationship and the mechanisms underlying biodiversity effects, including complementarity and selection effects, biomass allocation, vertical distribution of roots, and plant survival using a microcosm experiment. We also evaluated to what extent trophic and non‐trophic interactions are affected by abiotic conditions by studying drought effects. Our results show that biotic and abiotic conditions influence the shape of the biodiversity–ecosystem function relationship, varying from hump‐shaped to linear. For instance, total biomass increased linearly with plant richness in the presence of detritivores, but not in the absence of detritivores. Moreover, detritivore effects on belowground plant productivity were highly context dependent, varying in the presence of herbivores. Plant interactions with soil biota, especially with herbivores, influenced the mechanisms underlying diversity effects. Herbivores increased plant complementarity and modified biomass allocation and vertical distribution of roots. Furthermore, biotic–abiotic interactions influenced plant productivity differently across plant functional groups. Our findings emphasize the importance of complex biotic interactions underlying biodiversity effects, and that these biotic interactions may change with abiotic conditions. Despite minor changes in productivity in the short‐term, soil biota‐induced changes in plant–plant interactions and plant survival are likely to have significant long‐term consequences for ecosystem functioning. Considering the context‐dependency of multichannel interactions may contribute to reconciling differences among observed patterns in biodiversity studies. Further, abiotic conditions modified the effects of biotic interactions, suggesting that changes in environmental conditions may not only affect ecosystems directly, but also change the biotic composition of and dynamics within ecosystems.

Drought modulates interactions between arbuscular mycorrhizal fungal diversity and barley genotype diversity

“…Our results showed that the mycorrhiza colonization frequency of roots can mediate root biomass production, while this may also diminish under drought stress. This result further exemplifies how biotic interactions and biodiversity-ecosystem function relationships depend on environmental conditions 161 . Trait-based approaches with a temporal dimension are necessary to mechanistically understand identity effects, mycorrhizal functions and their temporal aspects 33,61,127 .…”

Plant diversity maintains multiple soil functions in future environments

“…Alternatively, diverse communities may have higher functioning because of an elevated probability of containing and becoming dominated by one or a few productive species (Loreau and Hector, 2001). Moreover, there is growing evidence that biotic interactions across trophic levels are important drivers of biodiversity effects (Maron et al, 2011; Schnitzer et al, 2011; Eisenhauer et al, 2012a) and that these interactions are significantly modulated by environmental conditions (Guerrero-Ramírez and Eisenhauer, 2017). As a consequence, biodiversity effects may depend on the environmental context, such as climatic conditions and resource availability (Craven et al, 2016; Guerrero-Ramírez et al, 2017), and thus may change in future environments.…”

Biodiversity influences the effects of oil disturbance on coastal ecosystems

“…Diversity effects arise from interactions among individuals and between individuals and their environments (Craven et al, 2016; Guerrero‐Ramirez & Eisenhauer, 2017). Because, environmental change—including disturbance—can modify the strength and direction of species interactions as well as how individuals’ response to a disturbance, diversity effects can vary across environmental conditions (Cardinale et al, 2000; Fridley, 2002; Steudel et al, 2012; Worm et al, 2002).…”