Differential wind tolerance of soil crust mosses explains their micro-distribution in nature

Wind has extensive effects on biological and ecological performances of organisms throughout the world. However, the responses of desert biological soil crusts to wind are still largely unexplored. Bryum argenteum and Didymodon vinealis are two predominant soil crust mosses that exhibit restricted, contrasting microhabitats with B. argenteum being excluded from higher wind speed microsites in the windward slopes of fixed sand dunes in the Tennger Desert, Northern China. We conducted this study to determine if wind has negative effects on the ecophysiological variables of the two soil crust mosses and whether D. vinealis possesses greater resistance to high wind speed than B. argenteum. The results showed that photosynthesis, respiration, PSII photochemical efficiency, photosynthetic pigments, shoot upgrowth, productivity and regeneration potential of the two soil crust mosses were all drastically inhibited due to the rapid drying, prolonged drought period and unfavorable coupling of moisture and temperature under high wind speed conditions. In addition, D. vinealis displayed stronger resistance to wind than B. argenteum based on all of the aspects mentioned above. Overall, the negative effects of wind on the physiology of soil crust moss and the differential resistance to wind observed in this study suggest that wind is an important determinant regulator influencing ecological micro-distribution patterns of soil crust moss in desert ecosystems.