接种蓝藻对生物结皮发育及荒漠土壤生态功能的影响

As a new sand-fixing method in desertification control, to promote the development of biological soil crusts (BSCs) via inoculating desert cyanobacteria is an innovative study first conducted by our researchers. Base on the above study, this project on the one hand intends to track and monitor the course of early cyanobacterial crust formation and development after cyanobacterial inoculation; on the other hand to investigate crust development and succession in the Crust Recovery Demonstration Zone where cyanobacteria have been inoculated in the different years, studying the effects of inoculating environmental conditions on the formation, development and succession of BSCs. In addition, in this project crust metabolic activity and soil physical and chemical characteristics are planned to analyze, in order to dynamically and systematically research crust and soil ecological functions, aiming at exploring the improving effects of cyanobacterial inoculation on desert soil ecological functions; as well as microscopic observation, cloning, high-throughput sequencing and chlorophyll fluorescence imaging technologies will be conjunctively used to analyze crust community structure and distribution patterns, and ultimately revealing the inherent biological mechanisms and their environmental regulation effects on the promotion of biological soil crust development and succession, and improvement of soil ecological functions after cyanobacterial inoculation in desert region. The results will not only be of great value in discussing the development and succession of BSCs, exploring the possibility and mechanisms of improving desert ecological functions from a point of view of crust recovery, but also provide an important theoretical guidance and scientific basis for the maintenance and management of BSCs, as well for crust application via cyanobacterial inoculation in desertification control.

作为荒漠化地区一种新型固沙方法，通过接种荒漠蓝藻促进生物结皮发育是由我国科研人员率先开展的一项创新性研究。本项目基于上述研究一方面拟通过接种蓝藻促进生物结皮恢复跟踪监测结皮早期形成发育过程；另一方面通过调查目前已经接种蓝藻恢复生物结皮示范区中结皮发育演替状况，从而探究接种环境条件对生物结皮发育演替的影响；通过结皮代谢活性监测与土壤理化分析对结皮及土壤生态功能进行动态、系统研究，探究接种蓝藻对荒漠土壤生态功能的改善作用；通过显微观察、克隆、高通量测序以及叶绿素荧光成像技术分析结皮群落结构组成以及分布模式，最终揭示荒漠地区接种蓝藻对于促进生物结皮发育演替以及土壤生态功能改善的内在生物学机制及其环境调控作用。本项研究的开展不仅对揭示生物结皮发育演替机理、探究荒漠生态功能改善的可能与机制具有重要价值，也将为人工接种蓝藻后结皮的维护管理以及在荒漠化治理方面的应用提供重要的理论基础与科学依据。

接种荒漠蓝藻促进生物结皮发育是由我国科研人员率先开展的一项创新性研究。本项目基于上述研究技术，一方面通过接种蓝藻促进生物结皮恢复跟踪监测结皮早期形成发育过程；另一方面通过调查目前已经接种蓝藻恢复生物结皮示范区中结皮发育演替状况，从而探究了生物结皮的发育演替对结皮群落结构组成、分布模式及相关生态功能的影响。通过本项目的研究，提出了微藻在流沙表面的生物膜节水培养模式，同时结合废水回用技术，探究了利用废水培养荒漠微藻的可行性，并实现了废水中氮磷营养物质90%以上的去除率，进一步拓宽了荒漠微藻的培养方法。在此基础上，完成了荒漠蓝藻的接种以及人工藻结皮的构建，并在结皮形成过程中跟踪监测了结皮的形成发育过程。结果证实接种蓝藻后生物结皮的发育演替遵循稳态转化理论，蓝藻的接种打破流沙上的微生物稳态进入藻结皮稳态。一些微区域藓结皮的发育进一步丰富了荒漠地表的稳态转化理论，提供了藻结皮到藓结皮演替的直接证据。随着生物结皮的发育演替，基于16S和18S rRNA基因结果表明蓝藻接种促进生物结皮发育的同时，微生物（包括原核和真核）群落出现异质性变化，尤其相对于流沙中绝对优势的Microcoleus以及较多的特有微生物操作分类单元（OTUs）而言，生物结皮的发育促进了固氮蓝藻的生长。生物结皮微生物群落结构结合结皮厚度、光合生物量、多糖含量等理化分析揭示了蓝藻群落随结皮发育的生态功能转变，即从早期与固碳、多糖分泌相关的土表结构维持逐渐转变为后期的固氮。同时，结合野外原位非降雨型水分积累、结皮光合活性和碳交换量，进一步揭示了结皮对非降雨型水分的促进积累和利用效率，最终提出了生物结皮固沙技术的非降雨型水分边界为≥0.08mm d-1的区域。此外，结合生物结皮叶绿素荧光成像及结皮分布模式分析，尤其对接种蓝藻促进生物结皮发育及其中微生物群落演替进行了功能与形态群分析，最终本研究表明接种Microcoleus vaginatus和Scytonema javanicum形成很好的互补模式，能够长期在结皮中维持其优势并促进结皮的发育。