Distinct co-occurrence patterns and assembly processes of abundant and rare taxa under cadmium stress in volcanic areas

Microorganisms play a crucial role in coping with environmental stresses such as heavy metals in terrestrial ecosystems. However, elucidating the environmental adaptations and ecological processes of abundant and rare taxa is a core but less known theme. The diversity, co-occurrence networks, and the assembly processes of abundant and rare taxa were compared and analyzed in volcanic soils. The findings indicated that the shannon and richness of rare taxa was generally higher than that of abundant taxa. Furthermore, compared with rare taxa, abundant taxa indicated greater stability and resistance. Co-occurrence patterns revealed that abundant taxa exhibited a higher number of interspecific interactions in response to cadmium (Cd) stress, and fungi and archaea generated higher modularity in high Cd environment. Additionally, the assembly process of abundant taxa in volcanic soils was mainly influenced by stochastic processes, whereas deterministic processes were increasingly enhanced in rare taxa. These findings provide value for understanding the assembly processes of bacteria, fungi, and archaea, and conduce to a deeper comprehension of the environmental adaptations exhibited by both abundant and rare taxa in extreme volcanic environments.