Scale-dependent causes and consequences of biodiversity loss
We are living in a time of rapid biodiversity change, caused by various human activities. But changes in biodiversity are often scale-dependent: local biodiversity gains can coincide with a homogenization of plant or animal communities across sites (regional biodiversity losses) and vice versa. Given this scale-dependence of biodiversity change, two key questions are: 1) at what spatial scale is human-driven biodiversity loss most severe, and 2) what are the consequences of biodiversity loss for the functioning of ecosystems at different spatial scales? My research focuses on these questions, using grassland plant communities and forests as model systems. I will first discuss how management activities, as well as human pressures, drive plant grassland plant diversity across various scales. One of the conclusions is that often-reported local-scale losses in plant diversity due to human pressures are often mirrored by homogenization at much larger spatial scales, whereby plant communities across different sites become increasingly similar over time. I will then discuss two types of scale-dependent consequences of biodiversity loss for ecosystem functioning. First, average levels of various ecosystem processes, such as biomass production, soil carbon storage and ecosystem stability, are affected by multiple scales of biodiversity loss, although not always predictable ways. Second, when ecological communities become increasingly similar to each other over time, the way how they function also becomes increasingly similar, resulting in ‘functional homogenization’ of ecosystems.
