Soil phosphorus determines the distinct assembly strategies for abundant and rare bacterial communities during successional reforestation

Abstract

Uncovering the mechanisms underlying the diversity patterns of abundant and rare species is crucial for terrestrial biodiversity maintenance. However, the response of abundant and rare community assembly to ecological succession has not been explored, particularly considering soil profiles. Here 300 soil samples were collected from reforestation ecosystems from depths of up to 300 cm and horizontal distances of 30–90 cm from a tree. We revealed that soil phosphorus not only affected alpha diversity and community structure, but also mediated the balance of stochastic and deterministic processes for abundant and rare sub-communities, which exhibited contrasting assembly strategies. The abundant sub-community changed from variable selection to stochasticity with the increase of phosphorus, while the rare sub-community shifted from homogeneous selection to stochasticity. Dispersal limitation was the main assembly process in the abundant sub-community, while the rare sub-community was governed primarily by homogeneous selection. Moreover, the relative influence of deterministic processes increased with succession for both sub-communities. At the scale of a single tree, stochastic processes increased with soil depth in rare sub-community, while deterministic processes increased with the radius from a single tree in the abundant subcommunity. Overall, our results highlight the importance of the soil phosphorus-driven assembly process in understanding the re-assembly and maintenance of soil bacterial diversity.