Microbial regulation of soil carbon properties under nitrogen addition and plant inputs removal

Ran Wu; Xiaoqin Cheng; Wensong Zhou; Hairong Han

doi:10.7717/peerj.7343

Microbial regulation of soil carbon properties under nitrogen addition and plant inputs removal

PeerJ. 2019 Jul 17:7:e7343. doi: 10.7717/peerj.7343. eCollection 2019.

Authors

Ran Wu¹, Xiaoqin Cheng¹, Wensong Zhou¹, Hairong Han¹

Affiliation

¹ Beijing Key Laboratory of Forest Resources and Ecosystem Processes, Beijing Forestry University, Beijing, China.

Abstract

Background: Soil microbial communities and their associated enzyme activities play key roles in carbon cycling in terrestrial ecosystems. Soil microbial communities are sensitive to resource availability, but the mechanisms of microbial regulation have not been thoroughly investigated. Here, we tested the mechanistic relationships between microbial responses and multiple interacting resources.

Methods: We examined soil carbon properties, soil microbial community structure and carbon-related functions under nitrogen addition and plant inputs removal (litter removal (NL), root trench and litter removal (NRL)) in a pure Larix principis-rupprechtii plantation in northern China.

Results: We found that nitrogen addition affected the soil microbial community structure, and that microbial biomass increased significantly once 100 kg ha^-1 a^-1 of nitrogen was added. The interactions between nitrogen addition and plant inputs removal significantly affected soil bacteria and their enzymatic activities (oxidases). The NL treatment enhanced soil microbial biomass under nitrogen addition. We also found that the biomass of gram-negative bacteria and saprotrophic fungi directly affected the soil microbial functions related to carbon turnover. The biomass of gram-negative bacteria and peroxidase activity were key factors controlling soil carbon dynamics. The interactions between nitrogen addition and plant inputs removal strengthened the correlation between the hydrolases and soil carbon.

Conclusions: This study showed that nitrogen addition and plant inputs removal could alter soil enzyme activities and further affect soil carbon turnover via microbial regulation. The increase in soil microbial biomass and the microbial regulation of soil carbon both need to be considered when developing effective sustainable forest management practices for northern China. Moreover, further studies are also needed to exactly understand how the complex interaction between the plant and below-ground processes affects the soil microbial community structure.

Keywords: Nitrogen addition; Plant inputs removal; Regulation; Soil carbon properties; Soil enzyme; Soil microorganisms.

Grants and funding

This study was financed by the National Key Research and Development Program of China (2016YFD0600205). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.