Data from: Effects of grazing on soil nitrogen spatial heterogeneity depend on herbivore assemblage and pre-grazing plant diversity

The spatial heterogeneity of limiting soil resources is an essential
factor determining ecosystem processes and function. It has been reported
that large herbivores can strongly impact the variation and spatial
distribution pattern of soil nitrogen (N). However, it remains unclear how
large herbivores affect soil spatial heterogeneity and whether this
influence is dependent on plant community diversity. Here we examined
effects of different herbivore assemblages [no grazing; cattle grazing
(CG); sheep grazing (SG); and mixed grazing (MG) of cattle and sheep] on
soil N spatial heterogeneity in grasslands with high and low pre-grazing
plant diversity in an eastern Eurasian steppe. We found that herbivore
grazing generated and maintained spatial patterns of soil nutrients,
depending on herbivore assemblage and the level of pre-grazing plant
diversity. CG increased the spatial heterogeneity of soil available N in
Leymus chinensis-dominated steppe meadows, which were independent of
pre-grazing plant diversity. However, the effects of SG and MG strongly
depended on grassland plant diversity, with an increased spatial
heterogeneity of soil available N in the high-diversity grassland, but not
in the low-diversity grassland. Synthesis and applications. We concluded
that in a L. chinensis-dominated eastern Eurasian steppe, cattle ranching
could be considered as an optimal grazing management protocol to improve
soil spatial heterogeneity because cattle grazing (CG) consistently
increased soil spatial heterogeneity in the context of both low and high
plant diversity. Nevertheless, soil spatial heterogeneity could be
improved by any herbivore grazing regime [CG and/or sheep grazing (SG)]
when high plant diversity is maintained. These findings highlight the
importance of conserving plant diversity to maintain grassland structure
and ecosystem function. In grassland systems with high plant diversity,
herbivore grazing and plant diversity would jointly improve soil spatial
heterogeneity, thus feeding back to maintain higher plant diversity.
Therefore, high plant diversity could generate a positive feedback loop of
herbivore–plant–soil interactions in grazed grassland systems. Our
findings indicate the importance of herbivore assemblages in maintaining
spatial heterogeneity in low- and high-diversity grassland systems.