The autotrophic community across developmental stages of biocrusts in the Gurbantunggut Desert

Abstract

Autotrophs, such as cyanobacteria, algae, and prokaryotic non-cyanobacterial autotrophs, play fundamental roles in biocrust development by adhering to soil particles and fixing CO2. The variation in autotrophic community structure, in particular that of prokaryotic non-cyanobacterial autotrophs, and the factors driving this variation during biocrust succession have not been revealed. In this study, we investigated the autotrophic communities in bare sand and three biocrust successional stages in the Gurbantunggut Desert by assessing the cbbL gene, which encodes the form I ribulose1,5-bisphosphate carboxylase/oxygenase (RuBisCO) large subunit. The cbbL gene profiles demonstrated that the abundance of cyanobacteria and algae (form IAB, 105–107 copies g−1 soil) and prokaryotic non-cyanobacterial autotrophs (form IC, ~107 copies g−1 soil) changed significantly as succession progressed. Stepwise multiple regression showed that soil water, organic carbon, total phosphorous, available potassium content and pH explained 95.7% of the variation in cyanobacterial and algal (form IAB) abundance. Soil water content explained 60.1% of the variation in prokaryotic non-cyanobacterial autotroph (form IC) abundance. Variation partitioning analysis showed that the variation in form IC community structure was related to soil nutrients (C, N, and P), ion content (Mg2+, Na+ and Ca2+) and physical soil properties (86.1% explained). The variation in form IAB community structure could be predictable by total potassium, total organic carbon and Na+ and Mg2+ content (37.1% explained). Our results showed significant shifts in both autotrophic abundance and community structure, and highlighted the combined effects of soil factors on autotrophic community variation during biocrust succession.