Microbial function regulates the effect of vegetation restoration on the contribution of biocrusts to soil respiration in drylands

Biocrusts are special components of dryland ecosystems and play important roles in ecosystem carbon cycles. Vegetation restoration not only affects carbon storage but also changes the characteristics of biocrusts. However, how vegetation restoration influences the contribution of biocrusts to soil carbon cycling in dryland ecosystems is poorly understood. Using continuous field measurements combined with metagenomic shotgun sequencing, we explored the effect and regulatory mechanisms of Caragana korshinskii vegetation restoration on the contribution of biocrusts to total soil respiration. We found that vegetation restoration increased the contribution of biocrusts to total soil respiration, with the biocrust contribution increasing from −5.6% for mixed biocrusts in a typical steppe to 17.1%, 18.1% and 19.6% for cyanobacteria–algae, lichen and moss biocrusts, respectively, in a Caragana korshinskii vegetation restoration area. The driving factors for total soil respiration changed from solely soil temperature to soil temperature and moisture after vegetation restoration. In contrast, the driving factors for soil respiration estimated for biocrust layers changed from precipitation alone to soil temperature and precipitation after vegetation restoration. We reveal that changes in microbial functional structure play important roles in regulating the effect of vegetation restoration and biocrusts on soil respiration. In addition, vegetation restoration also increases the microbial activity in biocrusted soils. This calls for an improved understanding of the effects of biocrusts on soil respiration under vegetation restoration scenarios to advance our ability to evaluate soil carbon releases from dryland ecosystems. Read the free Plain Language Summary for this article on the Journal blog. Read the free Plain Language Summary for this article on the Journal blog.