Landscape differentiation of soil bacteria and bacteria-soil-vegetation interactions in desert-oasis ecosystems

Abstract

Desertification control and oasis management are of strategic importance for the protection of ecological security and the achievement of sustainable development in arid regions. However, the role of soil microorganisms in desertification and oasification has been historically overlooked, especially for the influence of microbial communities on landscape change and the stability of soil-vegetation system in desert-oasis ecosystems. Here, using an environmental sampling approach combined with functional annotation, the landscape differentiation of soil bacterial diversity, community structure and functional traits, as well as the bacteria-soil-vegetation interactions were investigated in desert, oasis and desert-oasis ecotone habitats. The results showed that soil bacterial diversity increased significantly from desert, ecotone to oasis, and the highest spatial differentiation of bacterial diversity was observed in desert. The simplest and unique bacterial composition was detected in desert, which was dominant by Arthrobacter, Streptomyces, Burkholderia, etc. However, the phyla Actinobacteria, Proteobacteria, Acidobacteria, Chloroflexi, and the genus Candidatus_Nitrososphaera were the crucial biomarkers for distinguishing the composition differences across different landscapes. In terms of bacterial composition shift, it was far more challenging to go from ecotone to oasis than from desert to ecotone. Meanwhile, the most stable functional network was exhibited in oasis, while the simplest network was detected in ecotone rather than in desert. Relatively high soil moisture, total nitrogen, organic carbon, total phosphorus, and silt and clay proportions played decisive roles in improving microbial diversity, community structure and functional service, which would enhance the stability and diversity of desert-oasis ecosystems. Furthermore, increase in the relative abundances of functional genes, which were related to metabolism, environmental information processing, and organismal systems, may be harmful to nitrogen cycling and vegetation growth. These results conclude that the landscape differentiation of soil bacteria in desert, ecotone and oasis identifies the central role of bacterial interactions in ecosystem processes and highlights the importance of landscape stability control, forming a novel perspective of microbial behaviour in controlling landscape stability in desert-oasis ecosystems.