Conclusion
By analysing a comprehensive dataset of key belowground taxa, we show
that cessation of grazing on montane grasslands with a long history of
extensive sheep grazing leads to significant declines in ɑ-diversity of
soil organisms, while β-diversity of soil fauna and soil microbes show a
contrasting response. This illustrates that extensive grazing plays a
key a role in regulating biodiversity of belowground communities, and
highlights that the removal of grazing can result in a range of
deleterious effects, much in line with recent work on aboveground
invertebrate communities (Van Klink & WallisDeVries 2018). Large
swarths of Europe are currently being subjected to ‘rewilding’, an
approach to nature conservation that involves the cessation of historic
livestock grazing. Our results suggest that such a ‘rewilding’ approach
to nature conservation might not lead to an associated increase in the
diversity of belowground organisms. Rather, given that current densities
of natural grazers and browsers in historically grazed systems are low,
particularly compared to previous interglacial periods (Sandom et
al. 2014), we expect profound negative impacts of instantaneous
cessation of grazing on belowground diversity. This suggest that there
is a need for a gradual reduction of extensive grassland management and
a gradual increase of natural grazers when aiming to conserve
belowground biodiversity.
AcknowledgementsWe are extremely grateful to all landowners for allowing us to sample
their sites and Jerry Tallowin for providing help in finding suitable
research locations. Professor Rob Marrs is gratefully acknowledged for
his assistance during the work at the various locations in the Peak
District and Moor House, and we thank Aidan Keith, Centre for Ecology
and Evolution, Lancaster, for granting access to the Tullgren
extractors. Furthermore, we are grateful to all the people that assisted
with field work: Ciska Veen, Eva Thuijsman, Jan Degenaar and all
students from the HAS Hogeschool. MS was supported through an NWO
Rubicon grant (2014.08) and facilitated by an International Exchange
Award from the UK Biotechnology and Biological Sciences Research Council
(BBSRC) (Grant BB/L026406/1) to RDB and NF.
Table 1. Site details for all 12 locations; numbers correspond to Fig. 1