Climate change and intensive land use reduce soil animal biomass through dissimilar pathways

Abstract

Global change drivers, such as climate and land use, may profoundly influence body size, density, and biomass of organisms. It is still poorly understood how these concurrent drivers interact in affecting ecological communities. We present results of an experimental field study assessing the interactive effects of climate change and land-use intensification on body size, density, and biomass of soil microarthropods. We found that both climate change and intensive land use decreased their total biomass. Strikingly, this reduction was realized via two dissimilar pathways: climate change reduced mean body size, while intensive land use decreased population size. These findings highlight that two of the most pervasive global change drivers operate via different pathways when decreasing soil animal biomass. These shifts in soil communities may threaten essential ecosystem functions like organic matter turnover and nutrient cycling in future ecosystems. SignificanceMany important ecosystem functions are determined by the biomass of soil animal, however, how their biomass may respond to climate change and land-use intensification still remains unknown. We conducted a large field study to investigate the potential interaction between these two pervasive global change drivers, and disentangle the pathways where they contribute to the changes in soil animal biomass. Our findings are exceptionally novel by showing detrimental, but largely independent, effects of climate change and land-use intensity on soil animal biomass, and that these independent effects can be explained by two dissimilar pathways: climate change reduced mean body size, while intensive land use decreased population size. Notably, consistent climate change effects under different land-use regimes suggest that (1) the identified pathways may apply to a wide range of environmental conditions, and (2) current extensive land-use regimes do not mitigate detrimental climate change effects on ecosystems.