Bacterial Community Succession and Influencing Factors of Imperata Cylindrica Litter Decomposition in a Degraded Copper Tailings Dam of China

Abstract

Litter decomposition is a critical component of the ecological nutritional transformation process. It is particularly important to investigate characteristics and interactions of bacterial communities in litter decomposition in heavy metal polluted degrade areas, which will help clarify driving mechanisms of organic matter and nutrient cycling in mining areas that harbor contaminated soil. Imperata cylindrical was the dominant plant species in the degrade area investigated; thus, we selected this species as research object. Here we explore bacterial community characteristics and key microbial groups as well as driving factors of litter decomposition using in-situ litter decomposition experiments. The nutrient content of I. cylindrica decreased, while the litter pH status increased as decomposition progressed in one of the three sub-dams investigated (i.e., S516). Proteobacteria and Actinobacteriota were the dominant bacterial phyla during the different litter decomposition stages. Moreover, the role of Friedmanniella was critical in sustaining both structure and function of the bacterial community during the early decomposition stage. Quadrisphaera became the dominant species as litter decomposition progressed. Litter properties and enzyme activities both had significant effects on litter bacterial community characteristics, whose driving factors varied during different restoration stages. The bacterial community dynamics of litter were affected primarily by litter properties during the decomposition process. Furthermore, the most crucial factors that impacted bacterial litter structure were pH and copper content. Findings will help to deepen our understanding of litter decomposition mechanisms in degraded ecosystems, while also providing a scientific basis for improving effectiveness of material circulation and nutrient transformation in degrade ecosystems.