Vegetation succession on Arctic sand dunes controls organic matter accumulation and CO2 efflux from soil

Aeolian sand dunes are a widespread feature of Arctic and Subarctic ecosystems. The movement and stabilization of sand dunes determines soil development and vegetation expansion in these landscapes. Such ecosystem succession regulates organic carbon (C) accumulation in soil and CO2 emission from microbial mineralization of organic matter. This study aimed to investigate microbial activity in soils across a vegetation succession on typical sand dunes in the north of Western Siberia. We hypothesized that the sand dune’s stabilization by vegetation expansion leads to organic C accumulation and increases CO2 emission from soils, due to raised microbial biomass and activities. Five chronosequence sites representing an ecosystem succession were examined: windward slope, dune top, leeward slope of active dunes; young forest and climax on stabilized dunes. The sand dunes stabilization through vegetation increased soil organic C content from 1.1 g·kg−1 on active dunes to 7.3 g·kg−1 in the climax forest and decreased soil pH. The rate of organic C accumulation during the vegetation succession on the Arctic sand dunes was 0.1–0.2 g C kg−1 per decade. The CO2 efflux from soil and microbial biomass C content increased from areas on active dunes to the young and then to the climax forests, indicating a strong raise of microbial biomass content and activity along vegetation succession. The microbial metabolic quotient and the ratio of CO2 efflux from soil to organic C content were greatest on the leeward slope of active dunes and in the young forest, suggesting increase of labile organic matter availability for soil microorganisms. In contrast, the climax forest was characterized by the input of recalcitrant coniferous litter, leading to high organic C accumulation and microbial biomass C in soil, but by lower metabolic quotients. Concluding, vegetation succession on Arctic sand dunes and their stabilization increases C accumulation and microbial activities in soil. © 2025 Elsevier B.V.