生物土壤结皮固沙理论与实践

生物土壤结皮是由土壤微生物、藻类、地衣和苔藓等孢子植物类群与土壤颗粒形成的有机复合体，在全球干旱区地表广泛分布，是干旱地表生物覆被层的主要构建者。生物土壤结皮是荒漠植物群落演替的先锋类群，能够提高荒漠地表的稳定性，固定碳和氮等营养元素，增加土壤肥力，并在保持土壤水分方面发挥重要作用，因此在干旱区受损地表的生态修复方面具有广阔的应用前景。通过分析组成生物土壤结皮的物种更替与维持其结构的胶结方式转变之间的生态关系，阐释了生物土壤结皮固沙的生物学基础，提出在人工结皮恢复实践中，应选择以本地优势物种（如具鞘微鞘藻、齿肋赤藓和银叶真藓等）为目标种的生态学原则，并通过对目标物种的纯化、培养，完成由实验室至温室的扩繁过程，实现逐级扩大生产，为野外固沙应用提供充足种源。阐述了结皮野外接种恢复的最适物种组成、物理化学方式结合的组合模式，提出应从地表稳定性、土壤养分和结皮物种多样性等方面进行生长状况评估，梳理了中国在结皮人工恢复领域的研究进展和面临的问题与挑战，阐释了利用人工培养生物土壤结皮开展生态修复的应用前景。

The theory and practices of biological soil crust rehabilitation

Biological soil crusts(BSCs)is a complex of microorganism,cyanobacteria,lichen and moss that occur on or within top few centimeters of the soil surface.BSCs usually distributes in the dryland regions,and is an organizing principle in drylands.As the pioneers occurred in the desert ecosystems,BSCs can improve the stability of sand surface,fix carbon and nitrogen,increase soil fertility,and maintain soil moisture.In addition,BSCs plays a crucial role in the restoration of degraded soil surface.This article introduced the biological mechanism to fix sand through the ecological relationships between species replacements and the changes in ways of sand grain binding.The local dominant species(such as Microcoleus vaginatus,Syntichia caninevis and Bryum argenteum)in the field are recommended for the BSCs rehabilitation.Mass cultivation can be attained via the steps from species isolation in the laboratory to factory production in greenhouse,thus proving abundant inoculum for field growth.We also explored the species composition,physical and chemical assistance models during the field inoculation,and suggested that we need assess the growth according to surface stability,soil nutrient and species diversity of artificial BSCs.Last,we introduced the developments in sand fixation though artificial BSCs in China,and the experiences and challenges of BSCs rehabilitation.Our reviews suggest that artificial BSCs rehabilitation is a prospecting option for the ecological restoration.