Abstract Grazed alpine pastures have shaped landscapes of the European Alps for millennia, but have partially been abandoned since the 1950s. Re-grazing of abandoned pastures could preserve this cultural landscape with its high species diversity, but also alter soil carbon and nitrogen cycles, as well as microbial communities, potentially affecting ecosystem services (e.g., water purification, carbon and nitrogen storage). However, there is a lack of information on the resistance of soil characteristics to re-grazing effects. After characterising the distribution of vegetation types of an abandoned pasture in the German Alps, we investigated short-term effects of re-grazing on soil organic carbon and nitrogen biochemistry, soil microbial communities, and water quality along a gradient of grazing intensity. The abandoned grassland studied presented a remarkably high diversity of species and habitats even 60 years after abandonment. It was also found to be particularly rich in terms of microbial biomass, as well as in soil carbon and nitrogen. A few months after re-grazing started, extractable organic carbon, gross nitrogen mineralisation rates and inorganic nitrogen concentrations were increased only in intensively grazing-affected areas with bare soil (i.e. concentration of cows with excreta inputs), which insignificantly contributed to the overall area. Re-grazing did not affect the microbial abundance, whatever the grazing intensity, but induced a community shift towards a smaller proportion of fungi compared to bacteria and an increase of ammonia oxidizers (archaea/bacteria) under bare soil conditions. Concentrations of dissolved organic carbon and nitrate in the draining creek remained very low. Overall, re-grazing of pastures in the first season had very limited effects on microbial communities and associated carbon and nitrogen turnover and concentrations, highlighting the resistance of the studied alpine soils to extensive re-grazing. Our results indicate how to develop sustainable management strategies that preserve alpine pastures from degradation.

中文翻译：

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长期废弃的高山牧场土壤对短期重新放牧的高抵抗力

摘要 数千年来，放牧的高山牧场塑造了欧洲阿尔卑斯山的景观，但自 1950 年代以来已部分废弃。重新放牧废弃牧场可以保护这种具有高度物种多样性的文化景观，但也会改变土壤碳和氮循环以及微生物群落，从而可能影响生态系统服务（例如水净化、碳和氮储存）。然而，缺乏关于土壤特性对重新放牧影响的抵抗力的信息。在表征了德国阿尔卑斯山废弃牧场的植被类型分布后，我们研究了重新放牧对土壤有机碳和氮生物化学、土壤微生物群落以及沿放牧强度梯度的水质的短期影响。所研究的废弃草地即使在废弃 60 年后仍呈现出非常高的物种和栖息地多样性。还发现它在微生物生物量以及土壤碳和氮方面特别丰富。重新放牧开始几个月后，可提取有机碳、总氮矿化率和无机氮浓度仅在受密集放牧影响的裸土地区（即有排泄物投入的奶牛浓度）增加，对整个面积的贡献微不足道. 无论放牧强度如何，重新放牧都不会影响微生物丰度，但在裸土条件下，与细菌相比，会导致菌群向更小比例的真菌和氨氧化剂（古生菌/细菌）的增加方向转变。排水小溪中溶解的有机碳和硝酸盐的浓度仍然很低。总体而言，第一季牧场的重新放牧对微生物群落以及相关的碳和氮周转和浓度的影响非常有限，突出了所研究的高山土壤对广泛重新放牧的抵抗力。我们的研究结果表明如何制定可持续管理策略，以防止高山牧场退化。