The response mechanisms of soil N mineralization under biological soil crusts to temperature and moisture in temperate desert regions

• Higher temperatures stimulated the net nitrification and N mineralization rates.
• The net N mineralization rate reached its maximum at 85% of field water content.
• The moss-covered soils exhibited a higher N transformation rate.
• The algae-lichen-covered soils showed a lower net nitrification rate.

Soil nitrogen (N) mineralization is an important component of the N cycling process in desert ecosystems. However, the effects of biological soil crust (BSC), especially different patterns of BSCs (i.e. moss, algae-lichen), on net nitrification and N mineralization rates under climate-change conditions are still largely unexplored. To investigate the effects of temperature and moisture on net nitrification and N mineralization rates in BSC-dominated desert soils, and to highlight the regulatory role of BSC on N availability in the Tengger Desert, China, intact soil cores from three microhabitats (moss-covered, algae-lichen-covered, and bare soil) were incubated at six temperatures (−10, 5, 15, 25, 35, and 40 °C) and four moisture levels (29, 58, 85, and 170% field water content, FWC). Generally, moss-covered soil exhibited the highest net N transformation rate, whereas, algae-lichen-covered soil inhibited the nitrification process. Incubation temperature and moisture significantly affected net nitrification and N mineralization rates in all three microhabitats, in general that values were higher at the higher temperature (i.e. 25, 35, and 40 °C) compared to lower temperature (i.e. −10, 5, 15 °C). The net N mineralization rate for the three microhabitats peaked at 85% FWC. Overall, results indicated that BSCs, especially moss-dominated soils, increase net N transformation rate and N availability. Thus, they can make a contribution to plant growth and play a positive role in primary productivity under climate change in arid areas.