Data from: Livestock overgrazing disrupts the positive associations between soil biodiversity and nitrogen availability

Livestock overgrazing influences both microbial communities and nutrient
cycling in terrestrial ecosystems. However, the role of overgrazing in
regulating the relationship between soil biodiversity and nitrogen
availability remains largely unexplored. We performed long-term grazing
exclusion experiments across eight sites along precipitation gradient
covering three major types of grassland in northern China to compare the
linkage between soil microbial diversity and N availability in overgrazed
versus non-grazed conditions. We found a positive association between
fungal diversity and soil available N in non-grazed grasslands. However,
the positive association was absent in overgrazed environments. Bacterial
diversity is not related to soil available N in either non-grazed or
overgrazed grasslands. Moreover, in bacterial community, we found a
positive link between the relative abundance of Actinobacteria with soil
available N in non-grazed, but not overgrazed, grasslands. Instead we
found the links between relative abundance of Bacteroidetes and
Acidobacteria with soil available N in overgrazed grasslands, but not
non-grazed, grasslands. Our work provides evidence that the relationships
between microbial diversity and ecosystem functions are context-dependent,
and so microbial community diversity is likely not the major driver of
soil N mineralization in overgrazed grasslands. Our study suggests that
high intensity anthropogenic activities in grasslands restrains the
capacity of diverse soil microbial communities to sustain ecosystem
function, and more broadly the capacity of entire ecosystems to maintain
important ecosystem processes such as plant production. Our study also
indicates that the fundamental microbial communities associated with N
availability change with differing land management strategies (e.g.
livestock grazing).