Interactive effects of climate change and biodiversity loss on ecosystem functioning

TLDR

Climate change and biodiversity loss are expected to simultaneously affect ecosystems, yet how each driver mediates the other's impact remains poorly understood, especially given the non‑additive effects highlighted by the multiple stressor framework. We tested how rainfall changes and litter diversity jointly influence ecological processes in tank bromeliad ecosystems. We conducted a controlled experiment in tank bromeliad ecosystems, manipulating rainfall regimes and litter diversity to assess their combined effects on ecological processes. Litter diversity and rainfall changes interactively affected multiple functions: high litter diversity buffered altered rainfall on detritivore communities, shifted decomposition mechanisms from complementarity to dominance, suppressed methanogenesis by reducing microbial activity by 58%, and overall demonstrated that climate change and biodiversity loss interact in multifaceted ways.

Abstract

Climate change and biodiversity loss are expected to simultaneously affect ecosystems, however research on how each driver mediates the effect of the other has been limited in scope. The multiple stressor framework emphasizes non-additive effects, but biodiversity may also buffer the effects of climate change, and climate change may alter which mechanisms underlie biodiversity-function relationships. Here, we performed an experiment using tank bromeliad ecosystems to test the various ways that rainfall changes and litter diversity may jointly determine ecological processes. Litter diversity and rainfall changes interactively affected multiple functions, but how depends on the process measured. High litter diversity buffered the effects of altered rainfall on detritivore communities, evidence of insurance against impacts of climate change. Altered rainfall affected the mechanisms by which litter diversity influenced decomposition, reducing the importance of complementary attributes of species (complementarity effects), and resulting in an increasing dependence on the maintenance of specific species (dominance effects). Finally, altered rainfall conditions prevented litter diversity from fueling methanogenesis, because such changes in rainfall reduced microbial activity by 58%. Together, these results demonstrate that the effects of climate change and biodiversity loss on ecosystems cannot be understood in isolation and interactions between these stressors can be multifaceted.