Species-specific effects of biocrust-forming lichens on soil properties under simulated climate change are driven by functional traits

• Biocrusts are key drivers of ecosystem functioning in drylands, yet our understanding of how climate change will affect the chemistry of biocrust-forming species and their impacts on carbon (C) and nitrogen (N) cycling is still very limited. • Using a manipulative experiment conducted with common biocrust-forming lichens with distinct morphology and chemistry (Buellia zoharyi, Diploschistes diacapsis, Psora decipiens and Squamarina lentigera), we evaluated changes in lichen total and isotopic C and N and several soil C and N variables after 50 months of simulated warming and rainfall reduction. • Climate change treatments reduced δ13C and the C : N ratio in B. zoharyi, and increased δ15N in S. lentigera. Lichens had species-specific effects on soil dissolved organic N (DON), NH 4 + , β-glucosidase and acid phosphatase activity regardless of climate change treatments, while these treatments changed how lichens affected several soil properties regardless of biocrust species. Changes in thallus δ13C, N and C : N drove species-specific effects on dissolved organic nitrogen (DON), NH 4 + , β-glucosidase and acid phosphatase activity. • Our findings indicate that warmer and drier conditions will alter the chemistry of biocrust-forming lichens, affecting soil nutrient cycling, and emphasize their key role as modulators of climate change impacts in dryland soils.