The Qinghai-Tibetan Plateau (QTP) is one of the most sensitive areas to global climate change, with fragile ecosystems and complex habitats. Biological soil crusts (BSCs) are an important type of ground cover on the soil surface that plays an essential role in stabilizing the soil surface, regulating water distribution, and driving the carbon and nitrogen cycle. These capabilities can provide critical ecosystem services in extreme plateau regions. Given the key role of soil microbes in BSCs and their feedback effects on global climate change, it is critical to explore the role of habitat environmental factors in driving spatial variation in BSC microbial communities. 

Recently, a research team led by Prof. LI Dunhai from the Institute of Hydrobiology (IHB) of the Chinese Academy of Sciences revealed the diversity patterns, spatial distributions, and drivers of BSC prokaryotes and eukaryotes in four habitats on the QTP, and identified the roles of stochastic and deterministic processes in community assembly. This study was published in Science of The Total Environment.  

Based on vegetation growth and geomorphological characteristics, the researchers selected four typical habitats, Gobi (GB), alpine desert (AD), shrub meadow (SM) and forest grassland (FG) to collect well-developed biological soil crusts. They collected a total of 16 sites with 80 BSC samples and underlying soil samples, and the geographic characteristics of each sampling area. Meanwhile, the soil and BSC properties of the samples were determined, and the BSC microbial community diversity and structural characteristics were characterized by metagenomic sequencing. 

The results showed that the difference in BSC microbial communities between different habitats was driven by a combination of several environmental factors, among which soil organic carbon (SOC) was the most important factor affecting the spatial variability of prokaryotes, while soil water content (SWC) was the most significant factor affecting the spatial variability of eukaryotes. Under specific climate of the QTP, the spatial pattern of microbial communities in BSCs was controlled by precipitation rather than temperature.  

From the perspective of ecological processes, environmental filtering had a greater effect on the distribution of BSC microorganisms in plateau habitats than dispersal limitation. The assembly of prokaryotic communities was determined by deterministic processes at both the regional scale and local scale. The assembly process was mainly determined by habitat type, while the assembly of eukaryotic communities was determined by stochastic processes at both the regional and local scales.  

This study provides scientific references for predicting the distribution and resource conservation of BSCs under future climate change scenarios and provides important insights for ecological assessment and restoration management on the Tibetan Plateau.  

(Editor: MA Yun)