Biotic and abiotic properties of biocrus

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 led to increases
in the relative abundance of algal species in the Chlorophyta. The results
also indicated that eukaryotic algae played an important role in 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.