Vegetation succession of Arctic sand dunes

Vegetation succession determines organic matter inputs and affects soil respiration rates. The effects of primary vegetation succession on soil organic carbon (Corg) content and soil respiration (ER) in Arctic sand dune ecosystems have not yet been established. Using spatial analysis, this study investigated differences in soil Corg and ER at different stages of vegetation succession on a natural sand massif in northern Western Siberia. Five stages of primary vegetation succession were identified: windward dune slope (WS) stage, dune top (DT), leeward dune slope (LSD) on active dunes, young forest (YF), and climax forest (CF) on stable dunes. The study involved soil sample collection, CO2 emission measurements, vegetation description, and analyses of Corg, total nitrogen (Ntotal), microbial biomass carbon (Cmic), and soil acidity. Species richness varies greatly across the landscape: from zero on windward slopes of active dunes to 26 species in climax forest on stable dunes. Increased plant litter input leads to increase in soil acidity (from 6.1 pH at the initial successional stage to 4.7 pH in the climax forest), higher organic carbon content in the top 10 cm of soil from 0.06 % to 0.73 %, and an increase in the C/N ratio from 4.6 to 26.1 respectively. The minimum rates of soil and ground cover CO2 emission (0,7 g C m-2 day-1), basal soil respiration (0,5 mg C kg-1 day-1), and microbial biomass carbon (23 mg C kg-1) were observed in areas with active sand transport. Maximum values of soil respiration and microbial activity indices were observed on stable dunes at the final stage of succession in mature forest, with CO2 emission of 13.3 g C m-2 day-1, basal respiration of 7.4 mg C kg-2 day-1, and microbial biomass carbon of 150 mg C kg-1. The results confirm that vegetation succession during sand dune stabilization is the primary factor in increasing soil biological activity and carbon storage.