Title: Context dependency of biodiversity-ecosystem functioning realtions
Human domination of ecosystems has led to dramatic alterations of biodiversity, which has been shown to affect the functioning of ecosystems. However, much of what we know about the role of biodiversity in mediating ecosystem process and functioning stems from manipulative experiments that have mostly manipulated the number of species and largely been performed in isolated homogenous environments with artificially assembled communities that do not reflect natural observations. Yet, in natural systems, the restructuring of community composition, evenness and dominance occurs in response and alongside to multiple aspects of biotic and environmental change.
By incorporating more realistic changes in community evenness and species dominance identity in experimetnal studies we dmonstrate that both are important mediators of ecosystem process and functions. Changes in evenness can affect ecosystem properties, but the direction and magnitude of change depends on the dominant species identity, which can have disproportionate effects on ecosystem properties, especially at low evenness levels. While the general importance of species identity effects is a consistent feature across varying environmental context, the functional impacts of species are highly context dependent. Collectively, these results indicate that context dependent functional variability within each level of species richness alters biodiversity-ecosystem functioning relations, which means that the ecosystem consequences of natural and anthropogenic forcing will differ from current expectation.