Microbial Life‐History Strategies Shape Biocrusts Soil Multifunctionality Responses to Multi‐Year Snow‐Cover Change

Winter snowfall is a critical water source sustaining the survival and ecological functioning of biocrusts in desert ecosystems, yet how different biocrust types respond to altered snow-depth conditions and maintain soil multifunctionality (SMF) through microbial community adjustments and life-history strategies remains poorly understood. Based on a field snow-manipulation experiment, we compared SMF responses in cyanobacterial and lichen crusts under snow removal, ambient snow, and double-snow treatments across different treatment-duration categories and further explored the underlying microbial regulatory mechanisms. Cyanobacterial and lichen crusts exhibited contrasting SMF responses to altered snow conditions. SMF significantly increased in cyanobacterial crusts in the short-term treatment plots (1 year), whereas lichen crusts showed a significant decline only under short-term snow removal. In the medium- and long-term treatment plots (8 and 11 years), differences in SMF between altered-snow and ambient-snow conditions were reduced for both biocrust types. Lichen crusts mainly showed increases in bacterial and total microbial diversity under snow manipulation, whereas significant diversity responses in cyanobacterial crusts were primarily associated with fungi. Microbial life-history strategies showed clear but biocrust-type-specific associations with SMF. Random forest and structural equation modeling (SEM) analyses indicated that SMF in cyanobacterial crusts was strongly constrained by the S strategy, while Y-related metabolic pathways were positively associated with SMF; in contrast, SMF in lichen crusts was positively associated with the A strategy but negatively associated with the S strategy. Soil physicochemical properties also played an important role in regulating SMF, but their effects and interactions with microbial attributes differed between the two biocrust types. Overall, this study demonstrates that altered snow conditions regulate biocrust SMF through the coupling of soil environmental changes and microbial functional responses, with the underlying regulatory pathways strongly dependent on biocrust type.