Interactions between aridity and land-use on ecosystem
functioning
In this study, we observed significant synergistic effects of aridity
and overgrazing on plant species richness and SOC, as well as of aridity
and haying on aboveground biomass (Table 1, Fig. 4). These findings
suggest that the effects of land-use on grassland diversity and
functioning can be altered by climate. Overgrazing is a pervasive driver
of soil function loss (Bridges & Oldeman 1999), resulting in reductions
in SOC and aboveground biomass in arid lands, while detrimental effects
may be less pronounced in semiarid lands (Eldridge et al. 2011;
Anadón et al. 2014). In this study, grazing and haying effects on
ecosystem functioning were greater at more arid sites than those at more
humid sites. This may be due to the higher diversity and plant recovery
capacity in humid environments. The present results highlight that it is
more important to preserve biodiversity in arid regions to alleviate the
negative effects of land-use on grassland structure and ecosystem
functioning, while biodiversity may be particularly threatened in arid
lands.
Although there have been several studies on effects of diversity,
aridity, and land-use on grassland functioning at the global scale
(Maestre et al. 2012; Delgado-Baquerizo et al. 2013;
McSherry & Ritchie 2013; Petz et al. 2014; Ruppert et al.2015), the joint and synergistic effects of these factors have not been
examined at such a large scale as this study. Implications of our study
can provide guidelines for mitigating the impacts of global change and
improving adaptive grassland management. In the future, multi-factor
experiments with grazing or haying intensities at such large scale and
on the above-belowground mechanisms underlying these effects would
provide a more comprehensive understanding for sustainable grassland
management.