Prolonged warming leads to carbon depletion and increases nutrient availability in alpine soils

Summary

This field study quantifies long-term soil carbon and nutrient dynamics in alpine grasslands subjected to a 3 °C temperature increase via downslope transplantation over seven years. The warmed plots exhibited substantial soil organic carbon depletion (18% loss) driven by enhanced microbial mineralisation that exceeded plant carbon inputs, alongside increased soil nutrient availability. The findings suggest that warming-driven carbon losses in mountain soils may establish a positive feedback loop with climate change, with limited microbial acclimation offsetting adaptive responses.

Regional applicability

This study was conducted in the French Alps and provides mechanistic insights directly applicable to UK upland and mountainous regions (Scottish Highlands, Lake District, Snowdonia) that face similar rapid warming trajectories. The experimental methodology and findings on soil carbon vulnerability under warming are transferable to UK alpine and subalpine grassland management and natural capital accounting, though absolute rates will vary with local soil composition, vegetation, and snow regimes.

Key measures

Soil organic carbon (SOC) stocks, soil nutrient content, soil organic matter chemistry and thermal stability, labile organic matter pools, net ecosystem exchange (NEE), microbial activity, growing season length

Outcomes reported

The study measured soil organic carbon stocks, soil nutrient content, soil organic matter characteristics, microbial activity, and net ecosystem exchange following seven years of experimental warming in alpine grasslands. Warmed plots showed an 18% decrease in soil organic carbon stocks and increased nutrient availability through enhanced microbial mineralisation.

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