Maize stalk mulching significantly influences the cyanobacterial communities and alpha diversity in artificial cyanobacterial crusts in arid sandy areas

Abstract

Biological soil crusts are biotic soil layers formed by interactions between cyanobacteria, other microorganisms, and soil particles. Cyanobacterial crust represents the primary stage of biological soil crust succession and performs crucial ecological functions within desert ecosystems. These crusts play a vital role in ecological sustainability by not only enhancing surface soil stability and water regulation but also by contributing significantly to soil nutrient cycling and carbon/nitrogen fixation. Cyanobacteria are key pioneer species in newly-established cyanobacterial crust, and cyanobacterial communities and alpha diversity are strongly influenced by surface microenvironmental conditions. Maize straw mulching can improve the surface microenvironment (e.g., sum of effective wetting time, accumulated temperature) in arid sandy areas. However, its effects on cyanobacterial communities and alpha diversity in artificial cyanobacterial crusts are still unknown. Here, the effects of five different rates of maize stalk mulch coverage (0, 25 %, 50 %, 75 %, 100 %) + biocrust inoculation were tested in an artificial cyanobacterial crust cultivation experiment on the southeastern edge of the Tengger Desert, China. The drivers of changes in cyanobacterial communities and alpha diversity were explored by monitoring microenvironmental variation. It was found that dominant cyanobacterial species varied with maize stalk mulch coverage rate. Community composition was the most similar between the biocrust inoculum and artificial crusts under 25 %, 50 %, and 75 % mulch coverage (0.7; 0.6; 0.7); Cyanobacteria species abundance and richness first increased before decreasing with increasing mulch coverage, whereas evenness exhibited the opposite pattern. Additionally, sum of effective wetting time, average light intensity, average temperature and accumulated temperature significantly influenced (p < 0.05) cyanobacterial communities and alpha diversity. These results suggest that 25–50 % maize straw coverage improves the surface microenvironment and facilitates the growth and development of key cyanobacterial taxa. As such, this coverage rate may be ideal to support efforts to stabilize sand using artificial cyanobacterial crusts.