Availability of labile carbon controls the temperature-dependent response of soil organic matter decomposition in alpine soils

Summary

Abstract. Soil organic matter (SOM) decomposition in alpine environments is influenced by multiple factors including temperature and substrate quality. It is important to understand how these factors influence soil carbon dynamics. We incubated subalpine forest and pasture soils at 12.5, 16.5, and 20.5 °C for one year with and without addition of fresh grass litter to assess impacts on total organic carbon (TOC) and lignin dynamics. In the absence of litter, TOC losses were limited, accounting for 6.7 ± 2.4 % in forest soils and 3.3 ± 1.6 % in pasture soils after 360 d, with no consistent temperature effect. In contrast, litter addition strongly increased the decomposition of primary SOM, resulting in TOC losses of 11.8 ± 1.1 % in forest soils and 17.4 ± 1.9 % in pasture soils, which were