Dynamics in eukaryotic algal communities regulate bacterial and fungal communities as biocrusts develop in a temperate desert in Central Asia

Abstract Eukaryotic algae, as the primary group of photosynthetic autotrophs, exert a significant influence on the development and functions of biological crusts in dryland ecosystems. Despite their importance, there are substantial knowledge gaps on the composition of eukaryotic algal communities and their effects on the distributions of bacteria and fungi in dryland soils. This study examined the eukaryotic algal community along a successional sequence of biocrusts in the Gurbantunggut desert, while also investigating their patterns of co‐occurrence with bacteria and fungi through high‐throughput sequencing and bioinformatic analyses. The results showed that nitrogen and phosphorus levels played a crucial role in the regulation of changes in the abundance and composition of the algal community. In particular, changes in the structure of the algal community arise primarily from fluctuations in the main species, rather than from loss and appearance of species during the biocrust succession. The accumulation of nitrogen and phosphorus in the biocrust was associated with the decrease in the relative abundance of Chlorophyta. The results also indicated that eukaryotic algae played an important role in the affecting bacterial and fungal communities and significantly improved the stability of the microbial community, reflected by the robustness of co‐occurrence networks. The network analysis further indicated that eukaryotic algae affected the stability of microbial co‐occurrence networks either by acting as keystone taxa or associating with the keystone bacterial and fungal taxa. These findings reveal a clear mechanism by which soil nitrogen and phosphorus levels affected the composition of eukaryotic algae communities and further regulated bacterial and fungal communities during biocrust development, providing valuable information on the development and functional execution of biocrusts in dryland ecosystems. Read the free Plain Language Summary for this article on the Journal blog.