Circular and Linear Ecosystem Successions on Sand Dunes: Factors and Consequences

Unforested sandy areas near flood plains and riverbed plains formed by dunes, barchans, and accumulative berms are well common in northern Eurasia and Alaska indicating the complex history of climate periods in the Holocene and modern eras. Active dunes with simple plant communities are surrounded by stable dunes overgrown with taiga forests, and are predestined for investigation of initial vegetation and soil development. Based on climatic, geomorphological, vegetation and soil properties including soil microbiome, we analyzed the cyclic and linear development of ecosystems in a typical sand area in the lower part of the Nadym River, 100 km south of the Arctic Circle. Shift of wind direction during Holocene, as well as very slow vegetation development under these harsh climatic conditions, lead to circular ecosystem development without to reach a steady state. Arenosols with extremely sparse vegetation and undifferentiated horizons are typical for this circular ecosystem development. In contrast, faster development of vegetation on slightly stabilized soils in wind protected areas (enclaves) stabilize sand movement, and lead to soil formation in the direction of Podzols. Based on soil acidification by litter input and succession of microbial communities we concluded about the carbon and nutrient limitations during soil development. Summarizing, detailed analysis of initial ecosystem development chains on sand dunes in taiga allowed to elucidate the common phases of vegetation and soil succession, and clarify their cyclic and linear development.