Biocrust-forming lichens increase soil available phosphorus under simulated climate change

Drylands are important reservoirs of soil phosphorus (P) at the global scale, although large uncertainties remain regarding how climate change will affect P cycling in these ecosystems. Biocrust-forming lichens are important regulators of abiotic and biotic processes occurring in the soil surface, including nutrient availability and redistribution, across global drylands. However, their role as modulators of climate change impacts on soil P cycling is poorly known. We conducted a manipulative microcosm experiment to evaluate how six biocrust-forming lichens (Buellia zoharyi, Diploschistes diacapsis, Fulgensia subbracteata, Psora decipiens, Squamarina lentigera and Toninia sedifolia) with diverse morphology and chemistry affect soil available P concentration and the activity of acid phosphatase after 50 months of simulated ~2°C warming and 35% rainfall reduction. Lichens increased soil available inorganic and total available P, and the activity of acid phosphatase, although the magnitude of these effects was highly species-specific. Climate change treatments increased available organic P regardless of lichen species. Our findings provide novel experimental evidence of the importance of biocrusts as modulators of P cycling in drylands and highlight the necessity to take into account the identity of biocrust constituents when evaluating their effects on soil fertility. Highlights: Biocrust-forming lichens effects on soil phosphorus under simulated climate change were evaluated A microcosm experiment with warming and rainfall reduction and six lichen species was conducted Lichens increased available inorganic and total available P, and the activity of acid phosphatase Biocrust-forming lichens have species-specific effects on phosphorus cycling in dryland soils.