Factors affecting soil quality index and spatial variability of multifunction in dryland: Climate and biological soil crust development

Abstract

Abstract Background and Aims: Soil multifunctional (MF) and quality index (SQI) are essential indicators of soil function, productivity, and health, and the spatial variability of soil multifunctional (SVM) is a significant characteristic of soil heterogeneity. As fundamental components of drylands, biological soil crusts (BSCs) or biocrusts regulate soil MF, SQI, and SVM to global climate changes. Biocrusts affect the soil MF, SQI, and SVM; however, there is little information about the role of soil in interspaces of BSC patches with diverse biocrust types in regulating the response of multiple ecosystem functions to climate change. Methods We evaluated the relative importance of climate, soil environment, and biotic (e.g., BSC) variables as drivers of soil MF, SQI, and SVM at 74 sites in the Gurbantunggut Desert. Results We found that soil pH, soil EC, soil MF, and SQI increase with the development of BSC. Climate (MAP, MAT, MAW) and soil environment (soil pH, EC) affect soil MF and SQI. SVM displayed a significant decreasing trend with the increase of MAP and soil EC. Based on the SEM analysis, the interpretation rate of the model to the SVM was 24%. The SEM model shows that the climate has a significant positive effect on soil sand content, soil EC, and soil MF. Similarly, BSC development had a significant positive effect on soil EC, soil MF, and SQI. BSC development had no significant influence on the SVM. Conclusion These results indicate that future changes in climate may directly affect the desert soil MF, SQI, and SVM and indirectly affect soil MF and SQI by changes in soil environment (soil sand content, pH, EC) and BSC development. The findings contribute significantly to our understanding of the patterns and mechanisms driving soil MF, SQI, and SVM in drylands, which is important for predicting changes in ecosystem functioning under climate change.