Soil microbes cycle nutrients needed for plant growth; consequently, the state of these communities can have cascading effects on whole-ecosystem restoration following disturbance. Yet, the factors influencing microbial communities during secondary succession remain only partially understood. One particularly severe anthropogenic disturbance to soil is surface mining for natural resources, which displaces established communities and changes the soil environment. These changes may alter the composition of microbial communities by applying selective pressure on taxa (i.e., deterministic processes). Dispersal and ecological drift can also shape communities post-disturbance (i.e., stochastic processes). Understanding the successional dynamics governing soil microbial community assembly following disturbance can aid in the development of land reclamation strategies. We investigated the relative influence of stochastic and deterministic processes on soil microbial community succession using a chronosequence of reclaimed surface mines in West Virginia, USA ranging from 2-32 years post-reclamation. We hypothesized that deterministic factors would prevail in shaping communities due to the drastic nature of this disturbance. To address our hypothesis, we sequenced soil bacterial and fungal rRNA gene amplicons and applied a linear modeling approach to link deterministic (i.e., soil chemical and physical characteristics) and stochastic (i.e., time and space) factors to microbial community succession.
Results/Conclusions
The influence of deterministic factors on soil bacterial communities was ~7 times greater than that of stochastic factors. Similarly, fungal communities were influenced only by deterministic factors and not by stochastic factors. Of the deterministic factors examined, soil organic matter, texture, and pH emerged as the most influential on both bacterial and fungal community compositions. Soil nutrient content increased with time since reclamation indicating a larger scale recovery of this disturbed land, which is plausibly influenced by microbial processes. Our results indicate that reclaimed mine soils harbor dynamic microbial communities which are shaped predominately by soil chemical and physical properties following reclamation while stochastic processes such as dispersal and ecological drift have little influence. Taken together our results suggest that by managing key soil properties, it may be possible to accelerate microbial succession to develop communities which fit the ecological needs of the desired post-mining land use.