Yalin Zhou, Rong Hui, Shuanglang Li
The results revealed that UV-B radiation was the dominant driver of physiological and metabolic variation in BSCs, consistently suppressing photosynthetic performance and secondary metabolite accumulation across all BSC types. The strongest inhibition occurred in algal crusts, indicating high sensitivity but limited physiological plasticity. In contrast, lichen and moss crusts exhibited greater regulatory capacity and partial recovery under combined warming and reduced precipitation, suggesting stress-buffered metabolic adjustment. Notably, several physiological and metabolic traits exhibited partial recovery under combined stress treatments relative to the UV-B-only treatments, suggesting that altered temperature and moisture conditions may modulate the effects of UV-B through physiological buffering rather than yielding simple additive effects.
INTRODUCTION: Biological soil crusts (BSCs) are key components of dryland ecosystems, yet their physiological stability under concurrent changes in UV-B radiation, temperature, and precipitation remains poorly understood. In particular, how BSCs at different developmental stages regulate carbon acquisition and secondary metabolism under multifactor climate stress remains unclear.
METHODS: In this study, we investigated the physiological and metabolic responses of algal, lichen, and moss crusts exposed for two years to factorial combinations of warming and reduced precipitation (+1.5 °C and -8%) and UV-B enhancement (ambient, +18%, +24%) in open-top chambers (OTCs). We quantified photosynthetic traits (chlorophyll a, chlorophyll b, and gross primary productivity) and secondary metabolites (flavonoids, total phenolics, carotenoids, and extracellular polysaccharides).
RESULTS: The results revealed that UV-B radiation was the dominant driver of physiological and metabolic variation in BSCs, consistently suppressing photosynthetic performance and secondary metabolite accumulation across all BSC types. The strongest inhibition occurred in algal crusts, indicating high sensitivity but limited physiological plasticity. In contrast, lichen and moss crusts exhibited greater regulatory capacity and partial recovery under combined warming and reduced precipitation, suggesting stress-buffered metabolic adjustment. Notably, several physiological and metabolic traits exhibited partial recovery under combined stress treatments relative to the UV-B-only treatments, suggesting that altered temperature and moisture conditions may modulate the effects of UV-B through physiological buffering rather than yielding simple additive effects.
DISCUSSION: This study reveals the divergent adaptation strategies of BSCs at different developmental stages under combined climatic stresses. The results highlight the importance of incorporating successional-stage heterogeneity and physiological trade-offs into predictions of dryland ecosystem responses under future climate change.