Grazing exclusion has been applied as a suitable strategy for soil conservation worldwide, mainly on semiarid soils. However, it is unclear how grazing exclusion reduces the negative effects of overgrazing on the microbial community in the Caatinga biome. In our study, we assessed the bacterial community under three different soil managements in a semiarid region of the Brazilian Caatinga biome, as follows: (a) Native Caatinga vegetation (natural); (b) grazing exclusion (exclusion); and (c) overgrazing (grazed). The bacterial community was assessed through the sequencing of the V4 region of the 16S rRNA gene and analyzed soil chemical and physical properties were correlated with the bacterial community structure. Our results demonstrate that exclusion increases the content of soil carbon and nitrogen, and bacterial diversity, while grazed showed a reduction of ~31 and ~43% in organic C, compared to exclusion and natural, respectively. However, the changes in bacterial diversity were more expressive in a specific site (No. 1), suggesting that exclusion strategy could be a context‐dependent and complex approach to protecting or improving Caatinga soils. Moreover, grazed areas might restrain the potential of bacterial diversity to sustain ecosystem functions since nonbeneficial elements increased in grazed treatments, 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 ecosystem functioning. The Caatinga soil microbiome may be unable to maintain ecosystem services such as plant and animals' development under overgrazing management.

中文翻译：

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放牧排除可调节巴西Caatinga生物群落中高度退化的半干旱土壤中的细菌群落

放牧排除已被用作全球范围内土壤保护的合适策略，主要是在半干旱土壤上。但是，目前尚不清楚放牧排除如何减少过度放牧对Caatinga生物群落中微生物群落的负面影响。在我们的研究中，我们评估了巴西卡廷加生物群落半干旱地区三种不同土壤管理下的细菌群落，如下：（a）本地卡廷加植被（自然）；（b）放牧排斥（exclusion）；（c）过度放牧（放牧）。通过对16S rRNA基因的V4区域进行测序来评估细菌群落，并分析土壤化学和物理性质与细菌群落结构相关。我们的研究结果表明，排阻增加了土壤碳和氮的含量以及细菌的多样性，而放牧相比于排阻和自然分别减少了约31％和约43％的有机碳。但是，细菌多样性的变化在特定位点更具表达性（第1号），这表明排除策略可能是保护或改善Caatinga的背景相关且复杂的方法土壤。此外，放牧的地区可能会限制细菌多样性维持生态系统功能的潜力，因为放牧的处理中非有益元素增加，这与细菌群落呈负相关。我们的研究提供了新的证据，表明过度放牧引起的高强度干扰不仅会降低土壤肥力，而且可能会抑制细菌组成，从而影响生态系统的功能。在过度放牧管理下，Caatinga土壤微生物组可能无法维持生态系统服务，例如动植物的生长。