Dead Moss-Dominated Biocrusts Enhanced Soil Nutrients and Extracellular Enzyme Activities in a Temperate Desert

Abstract

As the most advanced stage of biological soil crusts, moss crusts are crucial for maintaining the stability of the desert soil surface and regulating the hydrological and biochemical processes. Continuous warming and extreme precipitation events have resulted in the death of desert moss-dominated biocrusts to varying degrees. However, there is still a lack of knowledge on how dead moss-dominated biocrusts influence nutrients cycles in desert soils. In this study, we selected moss-dominated biocrusts in the Gurbantunggut desert. Soil chemical properties and six types of extracellular enzyme activities were determined at different soil depths underneath living and dead moss-dominated biocrusts. The results showed that dead moss-dominated biocrusts significantly enhanced the content of carbon, nitrogen, phosphorus and related extracellular enzyme activities, with the most pronounced effect on nitrate content and nitrate reductase activity. Meanwhile, the dead moss-dominated biocrusts alleviated microbial nitrogen limitation to a certain extent, but had limited effect on carbon limitation. Total nutrients (soil organic carbon, total nitrogen, total phosphorus) and pH were the most important factors influencing vector length, while the most important factors influencing vector angle were available nutrients (NO₃⁻, NH₄⁺, available phosphorus) and pH. These findings shed light on the impact of biocrusts on biogeochemical cycles and the nutrients (total or available nutrients) and pH were the vital factors influencing C- and N- limitation of microorganisms. This highlights the need to pay more attention to the impact of biocrusts' death on soil nutrient cycling when formulating desert ecosystem management under global climate change.