Changes in Leaf Wax Components of Biological Soil Crusts Associated with Altered Vegetation in the Tengger Desert, Northwestern China

Purpose-The aim of this study was to reveal the effect of vegetation restoration on soil alkane accumulation, which contributes to exposing the developmental process of biological soil crusts (BSCs) in desert ecosystems at the molecular level and provides a basis for the restoration of desert ecosystems. Methods-A field survey was conducted in Shapotou area of Tengger Desert, with six sites revegetated for different durations (11, 21, 34, 58, 57, and 65 years) and adjacent control sites of mobile sand. The samples were analyzed with the support of gas chromatography–mass spectrometry (GC–MS). Results and conclusions-The alkane concentrations increased significantly with revegetation; short-chain alkanes (SCAs) were likely derived from microorganisms such as archaea, bacteria, and fungi; long-chain alkanes (LCAs) were probably associated with the flourishing of lichens and mosses. However, LCA dominance in the subsoil was due to microbial degradation and biosynthesis, and n-tritriacontane (nC33) may potentially be derived from Actinobacteria. Furthermore, SCAs had the greatest accumulation rate in the early stages of succession, while LCAs had in the later stages. This trend suggests that SCAs may be related to the early colonization of BSCs, whereas LCAs likely favor the stabilization of soil organic matter during the late stages of BSC development. An analysis of the alkane indicators showed that the soil environment gradually became wetter, and the biodegradation of organic matter gradually enhanced with BSC development. Multiple factors drove the increase in soil alkanes due to revegetation.