Abstract
There is widespread concern that cessation of grazing in historically
grazed ecosystems is causing biotic homogenization and biodiversity
loss. Here, we used 12 montane grassland sites along an 800-km
north-south gradient across the United Kingdom, to test whether
cessation of grazing affects local ɑ- and β-diversity of belowground
food webs. We show that cessation of grazing leads to strongly decreased
ɑ-diversity of both soil microbial and faunal diversity, particularly of
relatively rare taxa. In contrast, the β-diversity varied between groups
of soil organisms. While soil microbial communities exhibited increased
homogenization after cessation of grazing, we observed decreased
homogenization for soil fauna after cessation of grazing. Overall, our
results indicate that grazer exclusion from historically grazed montane
grasslands has far-ranging consequences for the diversity and
composition of belowground food webs, and underscore the importance of
grazers for maintaining the diversity of belowground communities, which
play a central role in ecosystem functioning.