Bryophytes and their symbiotic microorganisms in karst rocky desertification areas

Biological soil crusts (BSCs) are integral components of drylands on all continents of the earth and constitute a key biotic component of these areas as well as have a large number of ecological effects. However, much research on BSCs has mainly focused on arid and semi-arid areas, especially desert regions. Bryophytic crusts are considered the later and climax community of crust development, they not only have unique ecological function, but also has high biomass and obvious ecological effect, which plays an irreplaceable role in the restoration and reconstruction of degraded ecosystem. Karst rocky desertification has tremendously affected the hydrologic, soil, and ecologic conditions at various scales and consequently causes more geologic hazards such as droughts, floods, landslides, and land subsidence as well as seriously hinders the sustainable development of local economy. Therefore, it is very urgent to seek more sustainable measures to control rocky desertification and restore ecological environment. Bryophytic crusts have high ecological value and wide application prospect in the long-term management of karst rocky desertification. However, in the karst rocky desertification areas of southwest China, the research on bryophytic crusts is very limited. Therefore, in this project, we investigated carefully the diversity composition of bryophytic crusts growing on bare rocks in the karst rocky desertification regions in Guizhou Province, Southwest of China. Through the comprehensive analysis, Hypnum leptothallum and Hyophila involuta were classified as high drought-resistance species. Further microbial diversity and function analysis of Hypnum leptothallum and Hyophila involuta showed that the moss species and rocky desertification types affects the composition of the entire microbiome. Becteria were more sensitive in the microbiome as their communities changed strongly between moss species and drought resistance factors. Moreover, several species of fungi and bacteria can be significantly associated with three drought-resistant indicators: Pro, SOD and POD, which were closely related to the drought adaptability of mosses. Our results enforced the potential of microbial communities as one kind of promoters in the distribution pattern of early mosses succession.

生物土壤结皮（Biological Soil Crusts, BSCs）是全球各大洲干旱区的核心组成部分，既是这类区域的关键生物组成成分，同时具备多样的生态效应。然而，当前针对生物土壤结皮的研究多集中于干旱、半干旱区，尤其是荒漠地带。苔藓结皮（Bryophytic Crusts）被认为是结皮发育的后期顶极群落，其不仅具备独特的生态功能，还拥有较高的生物量与显著的生态效应，在退化生态系统的修复与重建中发挥着不可替代的作用。喀斯特石漠化（Karst Rocky Desertification）在不同尺度上严重干扰了水文、土壤与生态环境，进而引发干旱、洪涝、滑坡、地面沉降等多种地质灾害，同时严重阻碍了当地经济的可持续发展。因此，探寻可持续的石漠化治理与生态环境修复手段已迫在眉睫。苔藓结皮在喀斯特石漠化的长期治理中具备极高的生态价值与广阔的应用前景，但在中国西南喀斯特石漠化区域，针对苔藓结皮的研究仍十分匮乏。为此，本项目针对中国西南贵州省喀斯特石漠化区域裸岩上生长的苔藓结皮的多样性组成展开了细致调查。经综合分析，细枝灰藓（Hypnum leptothallum）与卷叶丛本藓（Hyophila involuta）被鉴定为高抗旱物种。进一步对这两种苔藓的微生物多样性与功能进行分析后发现，苔藓物种与石漠化类型会影响整个微生物组的组成结构。微生物组中的细菌群落更为敏感，其组成在不同苔藓物种与抗旱性因子间存在显著变化。此外，部分真菌与细菌类群与脯氨酸（Proline, Pro）、超氧化物歧化酶（Superoxide Dismutase, SOD）、过氧化物酶（Peroxidase, POD）这三项抗旱指标显著相关，而这些指标与苔藓的抗旱适应性密切相关。本研究结果进一步证实了微生物组在早期苔藓群落分布格局构建中的潜在促进作用。