Divergent adaptive strategies of different biological soil crusts to seasonal environmental fluctuations in a temperate desert

Abstract Pronounced seasonal fluctuations in Central Asian temperate deserts, where annual temperature variations can exceed 80 °C, have shaped unique environmental adaptation strategies in regional vegetation. However, it remains unclear how biological soil crusts (BSCs), a dominant desert land cover, respond to inter‐seasonal hydrothermal fluctuations and whether these adaptive strategies are consistent across different crust types. This study investigated cyanobacterial, lichen and moss crusts in the Gurbantunggut Desert to explore their seasonal adaptive strategies from the perspectives of biomass dynamics and non‐structural carbohydrate (NSC) allocation patterns. The results indicated that biomass in cyanobacterial and lichen crusts increased progressively from spring to the following spring, whereas moss crusts showed no significant variation. Regarding resource allocation, cyanobacterial crusts showed a steady increase in soluble sugars and the soluble sugar‐to‐starch ratio, suggesting they effectively utilize seasonal precipitation pulses to sequester carbon (C) for growth. In contrast, lichen and moss crusts exhibited an inverse relationship between soluble sugars and starch; specifically, during stress periods, they remobilize starch into soluble sugars to maintain cellular osmotic homeostasis. Notably, their environmental tolerances diverged: lichen crusts exhibited high thermal tolerance but were sensitive to low‐temperature stress, whereas moss crusts demonstrated robust chilling tolerance but were vulnerable to heat stress. In conclusion, our findings confirm that different BSC types employ distinctive survival strategies and stress‐tolerance mechanisms, suggesting a potential for seasonal ecological niche complementarity. This study provides novel insights into the physiological adaptation strategies of desert cryptogams in response to extreme environmental variability.