Land-use intensification can reduce soil carbon stocks and changes microbial community biodiversity and functionality. However, there is a lack of consensus on whether management consistently affects microbial biodiversity across geographic scales, and how this relates to altered soil function. From a regulatory and monitoring perspective, there is a need to identify functionally relevant indicators of land use in order to evaluate the progress of soil restoration approaches. We performed a landscape-scale survey of unimproved calcareous grasslands paired with local arable contrasts, and assessed the consistency of responses in a variety of soil, biotic and functional measures. In addition, adjacent grasslands undergoing restoration were assessed to identify soil microbial indicators of recovery. Organic matter content was consistently larger in grasslands than in arable fields, and increased with time in the restoring sites. Molecular comparisons of grassland versus arable soils revealed numerous bacterial, archaeal and fungal indicators, with more representatives of Ca. Xiphinematobacter, DA101, Bradyrhizobium, Rhodoplanes, Mycobacteria and Mortierella in old grassland soils, whereas Nitrososphaera, Sporosarcina and Alternaria infectoria were more abundant in arable soils. Extracellular enzymatic responses were more variable, with none of the eight investigated enzymes being consistent indicators of grassland or arable soils. Correlation analyses, incorporating the molecular and enzymatic responses across all surveyed soils, revealed that molecular indicators were more strongly correlated with soil organic matter increases with restoration of arable soils. Our results highlight that microbial taxa are among the most sensitive indicators of soil restoration, and we identify consistent responses of specific taxa to management across geographic scales. This discovery will be important for both the instigation and monitoring of soil restoration.

中文翻译：

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细菌和古菌类群是分布钙质草地土壤恢复的可靠指标

土地利用集约化可以减少土壤碳储量并改变微生物群落的生物多样性和功能。然而，关于管理是否会持续影响跨地理尺度的微生物生物多样性，以及这与土壤功能改变的关系，缺乏共识。从监管和监测的角度来看，有必要确定土地利用的功能相关指标，以评估土壤恢复方法的进展。我们对未改良的钙质草原与当地耕地对比进行了景观尺度调查，并评估了各种土壤、生物和功能措施的响应一致性。此外，对正在恢复的相邻草地进行评估，以确定恢复的土壤微生物指标。草地有机质含量始终高于耕地，并随着时间的推移在恢复地点增加。草地与耕地土壤的分子比较揭示了许多细菌、古菌和真菌指标，其中 Ca 的代表更多。Xiphinematobacter , DA101 , Bradyrhizobium , Rhodoplanes , Mycobacteria和Mortierella在旧草地土壤中, 而Nitrososphaera , Sporosarcina和Alternaria infectoria在可耕土壤中更为丰富。细胞外酶促反应的变化更大，所研究的八种酶中没有一种是草地或耕地土壤的一致指标。结合所有调查土壤的分子和酶反应的相关性分析表明，分子指标与土壤有机质随着耕地恢复而增加的相关性更强。我们的结果强调微生物类群是土壤恢复最敏感的指标之一，我们确定了特定类群对跨地理尺度管理的一致响应。这一发现对于土壤恢复的启动和监测都很重要。