Abstract Soil microorganisms communities regulate key functions in terrestrial ecosystems and contributes to the formation of stable organic matter and hence climate change mitigation. The structure, diversity and activity of soil microbial communities are influenced by the quantity and quality of organic compounds entering soils through the contribution of their root exudates and plant litter, which the microorganisms use as a substrate for biosynthesis and energy source. However, grazing effect on the soil microorganisms showed variable results dependent on the ecosystem under study. One of the main challenges of this millennium is the sustainability of agricultural production, especially in fragile soils such as those present in Patagonia. Therefore, our objective was to evaluate the responses of microbial biomass carbon (MBC), soil basal respiration (SBR), the derived coefficients and the abundance of fungi and bacteria under contrasting long-term grazing intensities in an environmental gradient. The study was established in three ecological areas Mata Negra Thicket (MNT), Dry Magellanic Steppe (DMS) and Humid Magellanic Steppe (HMS) with two grazing intensities. Soil samples were taken over two years in different seasons (autumn, winter, spring and summer). Results showed that biotic and abiotic factors (temperature and precipitation), plant communities and soil characteristics modulated the microbial structure and function in ecological area. On the other hand, high grazing intensity decreased the MBC and microbial coefficient (qM). There was a seasonal and interannual dynamic in the MBC and the bacteria and fungal communities, attributed mainly to temperature and precipitation. The results indicated that the effect of grazing intensity in soil microbial communities depends largely on intrinsic characteristics of each ecological area defined by the environmental gradient.

中文翻译：

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阿根廷巴塔哥尼亚南部土壤微生物群落对放牧强度的环境梯度的响应

摘要 土壤微生物群落调节陆地生态系统的关键功能，有助于形成稳定的有机物质，从而减缓气候变化。土壤微生物群落的结构、多样性和活性受到通过根系分泌物和植物凋落物的贡献进入土壤的有机化合物的数量和质量的影响，微生物将其用作生物合成和能源的底物。然而，放牧对土壤微生物的影响显示出取决于所研究的生态系统的不同结果。本世纪的主要挑战之一是农业生产的可持续性，特别是在脆弱的土壤中，例如巴塔哥尼亚的土壤。因此，我们的目标是评估微生物生物量碳 (MBC) 的响应，土壤基础呼吸（SBR）、衍生系数以及在环境梯度中长期放牧强度对比下真菌和细菌的丰度。该研究在三个生态区建立，即马塔内格拉丛林 (MNT)、干麦哲伦草原 (DMS) 和湿麦哲伦草原 (HMS)，具有两种放牧强度。土壤样本在不同季节（秋季、冬季、春季和夏季）进行了两年多的采集。结果表明，生物和非生物因素（温度和降水）、植物群落和土壤特性调节了生态区微生物的结构和功能。另一方面，高放牧强度降低了 MBC 和微生物系数 (qM)。MBC 以及细菌和真菌群落存在季节性和年际动态，主要受气温和降水影响。结果表明，放牧强度对土壤微生物群落的影响很大程度上取决于由环境梯度定义的每个生态区的内在特征。