Shifting Carbon Fractions in Forest Soils Offset 14 C‐Based Turnover Times Along a 1700 m Elevation Gradient

作者：Margaux Moreno‐Duborgel, Sia Gosheva-Oney, Beatriz González‐Domínguez, Mirjam Brühlmann, Luisa Minich, Negar Haghipour, Roman Flury, Claudia Guidi, Alexander S. Brunmayr, Samuel Abiven, Timothy I. Eglinton, Frank Hagedorn · 发表于：Global Change Biology · 年份：2025 · DOI：10.1111/gcb.70326 · 被引用次数：10 · 研究领域：Soil Carbon and Nitrogen Dynamics、Peatlands and Wetlands Ecology、Geology and Paleoclimatology Research

ABSTRACT Climate change impacts the soil carbon cycle, yet there is no scientific consensus on the vulnerability of soil organic carbon (SOC) stocks to global warming. Here, we studied soil organic matter (SOM) changes across 50 Swiss forest sites covering an elevation gradient from 270 to 2020 m, with dominant tree species changing from sub‐Mediterranean pubescent oak to mountain pine at treeline. We sought to assess how elevation, serving as an integrating variable for climate variation, affects the stocks, transformation state, and radiocarbon ( 14 C)‐based turnover of SOM fractions in the organic layer, as well as in particulate organic matter (POM) and mineral‐associated organic matter (MOM) fractions in forest mineral soils (0–20 cm). Our results show consistent enrichment in 13 C and 15 N across all SOM fractions with increasing elevation, indicating a ubiquitous transformation state among SOM fractions regardless of environmental conditions. However, C stocks in the organic layer and in mineral soil POM increased proportionally relative to MOM with increasing elevation. Additionally, 14 C‐based turnover times in the organic layer, the free POM, and the fine MOM fractions increased with elevation, indicating slower SOM processing and a reduced transformation of POM to MOM under harsher climatic conditions. In contrast to individual SOM fractions, total SOC stocks and 14 C‐based turnover times in the bulk mineral soil showed no elevational pattern. This indicates that w...