In the face of intensifying global climate change, shifting spatiotemporal heterogeneity of precipitation patterns profoundly affects ecosystem stability. In arid regions with sparse higher plant cover, biological soil crusts (Biocrusts), dominated by desert cyanobacteria as keystone species, drive critical ecological functions such as carbon-nitrogen cycling and soil-water conservation through microbial community dynamics. However, traditional research has largely focused on the effects of single annual mean precipitation (MAP) on ecosystems, often overlooking the multifaceted characteristics of precipitation patterns (e.g., variability, frequency) and their cascade effects mediated by microbial communities. 

In a recent study published in Global Ecology and Biogeography, a research team led by Prof. HU Chunxiang from the Institute of Hydrobiology (IHB) of the Chinese Academy of Sciences revealed the cascade mechanism through which multifaceted precipitation traits regulate biocrust multifunctionality via microbial diversity. The study, conducted in arid regions of northwestern China, systematically analyzed 38 years of daily precipitation records alongside multitrophic microbial community characteristics. 

Through historical precipitation data analysis, the researchers discovered that precipitation variability (PV), defined as the magnitude of fluctuation in rainfall intensity, exhibited stronger explanatory power for biocrust multifunctionality than MAP. High precipitation variability was associated with reduced relative abundances of key functional taxa in soil microbial communities and promoted the aggregation of species with low functional importance. This finding highlights the limitations of traditional MAP-based climate-response models and underscores the potential threats of extreme precipitation fluctuations to arid-region ecosystems.

The researchers further dissected the contribution patterns of microorganisms across trophic levels to multifunctionality: heterotrophic bacteria and fungi primarily maintained local-scale functionality (α-multifunctionality) via species richness, whereas photoautotrophic cyanobacteria drove functional stability through phylogenetic diversity (i.e., evolutionary dissimilarities among species). This discovery suggests that functional-group-specific diversity analyses can more accurately capture microbial contributions to ecosystem processes. 

Quantifying the role of microbial β-diversity (i.e., spatial species turnover) in multifunctionality, the results indicated that species replacement (rather than richness difference) across microbial communities was the core mechanism sustaining regional-scale multifunctionality differences/asynchrony (β-multifunctionality). When local functions were disrupted by precipitation fluctuations, species replacement in adjacent areas maintained overall ecosystem stability through functional complementarity. This insight provides a new perspective on the spatial resilience of desert ecosystems. 

Through structural equation modeling, a cascading process was identified where the indirect effect of precipitation heterogeneity, regulated by microbial β-diversity, accounted for a higher proportion of variance in β-multifunctionality than direct climate influence. This indicates that regulating soil microbial community structure through inoculation and other methods may effectively buffer the impact of climate change on arid ecosystems. 

By constructing a cascade framework of "multifaceted precipitation patterns-microbial diversity-ecosystem functions", this study clarifies the limitations of single-dimensional climate-response research. These findings provide novel insights for desert ecological restoration. It is critical to prioritize cyanobacterial strains with distinct phylogenetic profiles during artificial biocrust cultivation to enhance functional stability, and to implement long-term monitoring of precipitation variability effects in climate-sensitive regions.

(Editor: MA Yun)