Abstract
In karst rocky desertification areas, bryophytes coexist with algae, bacteria, and fungi on exposed calcareous rocks to form a bryophyte crust, which plays an irreplaceable role in the restoration of karst degraded ecosystems. We investigated the biodiversity of crust bryophytes in karst rocky desertification areas from Guizhou Province, China. A total of 145 species in 22 families and 56 genera were identified. According to frequency and coverage, seven candidate dominant mosses were screened out, and five drought-resistant indexes of them were measured. Hypnum leptothallum, Racopilum cuspidigerum, and Hyophila involuta have high drought adaptability. We explored the interactions between two dominant mosses (H. leptothallum, H. involuta) and the structure of microbial communities in three karst rocky desertification types. Microbial diversity and function analysis showed that both moss species and karst rocky desertification types affect microbial communities. Moss species much more strongly affected the diversity and changed the community composition of these microbial groups. Bacteria were more sensitive in the microbiome as their communities changed strongly between mosses and drought resistance factors. Moreover, several species of fungi and bacteria could be significantly associated with three drought-resistant indexes: Pro (free proline content), SOD (superoxide dismutase activity), and POD (peroxidase activity), which were closely related to the drought adaptability of mosses. Our results enforced the potential role of moss-associated microbes that are important components involved in the related biological processes when bryophytes adapted to arid habitats, or as one kind of promoters in the distribution pattern of early mosses succession in karst rocky desertification areas.
Highlights
Karst rocky desertification is a process of land degradation involving serious soil erosion, extensive exposure of basement rocks, a drastic decrease in soil productivity, and the appearance of a desert-like landscape (Wang et al 2004a)
We have considered firstly the frequency, and 9 species, namely H. leptothallum, Didymodon fallax, H. involuta, T. kanedae, Hyophila javanica, Bryum argenteum, Trichostomum crispulum, Palamocladium euchloron, and Didymodon constrictus var. constrictus, have been screened out
The results demonstrated that the system of drought resistance indexes of Pro, POD, and superoxide dismutase (SOD) and the combined microorganisms can be more helpful for bryophyte adaption to karst rocky desertification
Summary
Karst rocky desertification is a process of land degradation involving serious soil erosion, extensive exposure of basement rocks, a drastic decrease in soil productivity, and the appearance of a desert-like landscape (Wang et al 2004a). As a result of intensive land use, this kind of rocky landscape is caused by degrading the fragile subtropical karst environment (Wang et al 2004b). The karst rocky desertification has tremendously affected hydrologic, soil, and ecologic conditions at various scales and causes various geologic hazards, such as droughts, floods, landslides, and land subsidence. In Southwest China, Guizhou Province is a central area to various provinces, including Yunnan, Guangdong, Chongqing, Hunan, Hubei, and Sichuan, and the Guangxi Zhuang autonomous region, and is the largest ecologically fragile karst region in the world (Yuan 2014; Jiang et al 2014; Xiong and Chi 2015; Fang and Li 2017; Chen et al 2019). Karst rocky desertification seriously hinders the sustainable development of local economy, society, and ecology
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