Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China.
School of Resources and Environmental Engineering, Wuhan University of Technology, Wuhan 430072, China.
Sci Total Environ. 2015 Dec 15;538:492-9. doi: 10.1016/j.scitotenv.2015.08.066. Epub 2015 Aug 28.
Biological soil crusts play important ecological functions in arid and semi-arid regions, while different crust successional patterns appeared in different regions. Therefore in this study, the environmental conditions between Shapotou (with cyanobacterial, lichen and moss crusts) and Dalate Banner (with only cyanobacterial and moss crusts) regions of China were compared to investigate why lichen crusts only appeared in Shapotou; at the same time, artificial moss inoculation was conducted to find out the environmental factors promoting crust succession to moss stage. The results showed lichen crusts always developed from cyanobacterial crusts, which provide not only the stable soil surface, but also the biomass basis for lichen formation; furthermore, addition of crust physicochemical characteristics (primarily silt content) play a facilitating effect on lichen emergence (R(2)=0.53). The inoculation experiment demonstrated early crust soil surface and enough water holding content (>4%) provided the essential guarantee for moss germination. Our results show that there is heterogeneity in crust succession in different regions, which may be mainly affected by the ambient soil microenvironments. It is concluded that a positive feedback mechanism is expected between crust succession and ambient soil microenvironments; while a negative feedback mechanism forms between crust succession and free living cyanobacteria and algae.
生物土壤结皮在干旱和半干旱地区发挥着重要的生态功能，而不同的结皮演替模式出现在不同的地区。因此，本研究比较了中国沙坡头（具有蓝藻、地衣和苔藓结皮）和达拉特旗（仅具有蓝藻和苔藓结皮）地区的环境条件，以调查为什么地衣结皮仅出现在沙坡头；同时，进行了人工苔藓接种实验，以找出促进结皮演替到苔藓阶段的环境因素。结果表明，地衣结皮总是从蓝藻结皮发育而来，蓝藻结皮不仅提供了稳定的土壤表面，还为地衣形成提供了生物量基础；此外，结皮物理化学特性（主要是粉土含量）的增加对地衣的出现具有促进作用（R(2)=0.53）。接种实验表明，早期的结皮土壤表面和足够的持水含量（>4%）为苔藓发芽提供了必要的保证。我们的研究结果表明，不同地区的结皮演替存在异质性，这可能主要受到环境土壤微环境的影响。可以得出结论，结皮演替与环境土壤微环境之间存在正反馈机制；而结皮演替与自由生活蓝藻和藻类之间则形成负反馈机制。
