Alpine and prealpine grasslands provide various ecosystem services and are hotspots for the storage of soil organic C (SOC) in Central Europe. Yet, information about aggregate-related SOC storage and its controlling factors in alpine and prealpine grassland soils is limited. In this study, the SOC distribution according to the aggregate size classes large macroaggregates (> 2000 μm), small macroaggregates (250–2000 μm), microaggregates (63–250 μm), and silt-/clay-sized particles (< 63 μm) was studied in grassland soils along an elevation gradient in the Northern Limestone Alps of Germany. This was accompanied by an analysis of earthworm abundance and biomass according to different ecological niches. The SOC and N stocks increased with elevation and were associated with relatively high proportions of water-stable macroaggregates due to high contents of exchangeable Ca2+ and Mg2+. At lower elevations, earthworms appeared to act as catalyzers for a higher microaggregate formation. Thus, SOC stabilization by aggregate formation in the studied soils is a result of a joined interaction of organic matter and Ca2+ as binding agents for soil aggregates (higher elevations), and the earthworms that act as promoters of aggregate formation through the secretion of biogenic carbonates (low elevation). Our study highlights the importance of aggregate-related factors as potential indices to evaluate the SOC storage potential in other mountainous grassland soils. Graphical abstract

中文翻译：

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钙质高山和前高山草地土壤中聚集体碳储存的生物和非生物控制

高山和前高山草原提供各种生态系统服务，是中欧土壤有机碳 (SOC) 储存的热点。然而，关于高山和前高山草地土壤中与骨料相关的 SOC 储存及其控制因素的信息是有限的。在本研究中，SOC 分布根据聚集体尺寸分类：大团聚体（> 2000 μm）、小团聚体（250–2000 μm）、微团聚体（63–250 μm）和粉砂/粘土大小的颗粒（< 63 μm） ) 在德国北部石灰岩阿尔卑斯山沿海拔梯度的草地土壤中进行了研究。这伴随着根据不同生态位对蚯蚓丰度和生物量的分析。由于可交换 Ca2+ 和 Mg2+ 含量高，SOC 和 N 库随海拔升高而增加，并且与较高比例的水稳性大团聚体相关。在较低海拔处，蚯蚓似乎充当了更高微团聚体形成的催化剂。因此，在研究的土壤中通过聚集体形成稳定 SOC 是有机物质和 Ca2+ 作为土壤聚集体（较高海拔）的粘合剂以及蚯蚓通过分泌生物碳酸盐作为聚集体形成促进剂相互作用的结果（低海拔）。我们的研究强调了与聚集体相关的因素作为评估其他山区草地土壤 SOC 储存潜力的潜在指标的重要性。图形概要 蚯蚓似乎充当了更高微团聚体形成的催化剂。因此，在研究的土壤中通过聚集体形成稳定 SOC 是有机物质和 Ca2+ 作为土壤聚集体（较高海拔）的粘合剂以及蚯蚓通过分泌生物碳酸盐作为聚集体形成促进剂相互作用的结果（低海拔）。我们的研究强调了聚集体相关因素作为评估其他山区草地土壤 SOC 储存潜力的潜在指标的重要性。图形概要 蚯蚓似乎充当了更高微团聚体形成的催化剂。因此，在研究的土壤中通过聚集体形成稳定 SOC 是有机物质和 Ca2+ 作为土壤聚集体（较高海拔）的粘合剂以及蚯蚓通过分泌生物碳酸盐作为聚集体形成促进剂相互作用的结果（低海拔）。我们的研究强调了与聚集体相关的因素作为评估其他山区草地土壤 SOC 储存潜力的潜在指标的重要性。图形概要 蚯蚓通过分泌生物碳酸盐（低海拔）促进聚集体形成。我们的研究强调了与聚集体相关的因素作为评估其他山区草地土壤 SOC 储存潜力的潜在指标的重要性。图形概要 蚯蚓通过分泌生物碳酸盐（低海拔）促进聚集体形成。我们的研究强调了与聚集体相关的因素作为评估其他山区草地土壤 SOC 储存潜力的潜在指标的重要性。图形概要