Grazing exclusion regulates bacterial community in highly degraded
semiarid soils from Brazilian Caatinga biome
Abstract
Grazing exclusion (GE) has been applied as a suitable strategy to soil
conservation worldwide, mainly in semiarid soils. However, it is unclear
how GE management reduces the negative effects of overgrazing on the
microbial community. In this study, we assessed the bacterial community
in three different soil management belonged to a semiarid region from
the Brazilian Caatinga biome, as follows: Native Caatinga (NC), Grazing
exclusion (GE), and a highly degraded area by Overgrazing (OG). The
bacterial community was assessed through the sequencing of the V4 region
of the 16S rRNA gene. We also analyzed soil chemical and physical
properties and correlated with bacterial community composition, and α-
and β- diversities. Our results demonstrated that GE increases the
content of soil C, N, and bacterial diversity. However, the changes in
bacterial diversity were significant in a specific site (nº 1),
suggesting that GE strategy could be a context-dependent and a complex
approach to Caatinga soils. Moreover, overgrazing might restrain the
potential of bacterial diversity to sustain ecosystem functions, since
non-beneficial elements (e.g., Na+ and Al3+) increased in OG, which
presented a negative correlation with the bacterial community. Our study
provides novel evidence that high-intensity disturbance by overgrazing
could not only reduce soil fertility, but it may also restrain bacterial
composition, with implications on environmental functioning. Thus, the
Caatinga soil microbiome may be unable to maintain ecosystem services
such as plant and animals’ development under overgrazing management.