A meta-analysis on decomposition quantifies afterlife effects of plant diversity as a global change driver

Biodiversity loss can alter ecosystem functioning; however, it remains unclear how it alters decomposition—a critical component of biogeochemical cycles in the biosphere. Here, we provide a global-scale meta-analysis to quantify how changes in the diversity of organic matter derived from plants (i.e. litter) affect rates of decomposition. We find that the after-life effects of diversity were significant, and of substantial magnitude, in forests, grasslands, and wetlands. Changes in plant diversity could alter decomposition rates by as much as climate change is projected to alter them. Specifically, diversifying plant litter from mono- to mixed-species increases decomposition rate by 34.7% in forests worldwide, which is comparable in magnitude to the 13.6–26.4% increase in decomposition rates that is projected to occur over the next 50 years in response to climate warming. Thus, biodiversity changes cannot be solely viewed as a response to human influence, such as climate change, but could also be a non-negligible driver of future changes in biogeochemical cycles and climate feedbacks on Earth. There is evidence that reducing plant litter diversity may slow litter decomposition rate. Here, Mori and colleagues perform a global meta-analysis of litter-bag studies to show that mixed-species litter assemblages decompose faster than monospecific assemblages, with a magnitude comparable to the predicted effect of climate warming.