Abstract:
Covering approximately 40% of land surfaces, grasslands provide critical ecosystem services
that rely on soil organisms. However, the global determinants of soil biodiversity and functioning
remain underexplored. In this study, we investigate the drivers of soil microbial and
detritivore activity in grasslands across a wide range of climatic conditions on five continents.
We apply standardized treatments of nutrient addition and herbivore reduction, allowing us
to disentangle the regional and local drivers of soil organism activity. We use structural
equation modeling to assess the direct and indirect effects of local and regional drivers on soil
biological activities. Microbial and detritivore activities are positively correlated across global
grasslands. These correlations are shaped more by global climatic factors than by local
treatments, with annual precipitation and soil water content explaining the majority of the
variation. Nutrient addition tends to reduce microbial activity by enhancing plant growth,
while herbivore reduction typically increases microbial and detritivore activity through
increased soil moisture. Our findings emphasize soil moisture as a key driver of soil biological
activity, highlighting the potential impacts of climate change, altered grazing pressure, and
eutrophication on nutrient cycling and decomposition within grassland ecosystems.
Description:
DATA AVAILABILITY : The source data that support the findings of this study can be found in the
supplementary data (Figs. 1a, b, 2 and 4 were created with Data 1, Fig. 1c and Fig. 3 with
Data 2). All other data are available from the corresponding author on reasonable
request.
CODE AVAILABILITY : The code is available from the corresponding author upon request.
