Impact of plant carbon inputs on soil bacterial communities and nitrogen cycle functions in temperate steppe

Abstract

Background and aims

Plants influence soil microbial communities through aboveground litter and root inputs. However, studies on the effects of various plant carbon inputs on soil microbial communities in grassland ecosystems are limited.

Methods

We characterized bacteria, ammonia-oxidizing bacteria and ammonia-oxidizing archaea using 16S rRNA amplicon sequencing and quantified the amoA gene via real-time PCR. We assessed the impacts of different carbon inputs (litter addition, litter removal, plant removal, and their interactions) on soil bacterial community structure, composition, nitrogen cycle functions, co-occurrence networks and assembly in a temperate grassland ecosystem following over a decade of experimental manipulations.

Results

Plant removal significantly affected soil total carbon content and the ratio of total carbon to total nitrogen content. The impact of plant removal was stronger than that of litter changes, significantly influencing bacterial community structure. Compared to ammonia-oxidizing archaea, ammonia-oxidizing bacteria dominated semi-arid grassland communities, and plant removal inhibited potential denitrification and nitrogen fixation groups. Notably, plant removal increased the complexity but reduced the stability of bacterial co-occurrence networks. It also enhanced deterministic processes and decreased the relative contribution of stochastic processes in bacterial communities.

Conclusions

This study elucidates the effects of various carbon input patterns on soil bacterial communities, highlighting their importance for comprehensively understanding the stability of these communities and their role in nitrogen cycling in temperate grasslands amid global change.