Wu Ran, Cheng Xiaoqin, Zhou Wensong, Han Hairong
Beijing Key Laboratory of Forest Resources and Ecosystem Processes, Beijing Forestry University, Beijing, China.
PeerJ. 2019 Jul 17;7:e7343. doi: 10.7717/peerj.7343. eCollection 2019.
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.
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 plantation in northern China.
We found that nitrogen addition affected the soil microbial community structure, and that microbial biomass increased significantly once 100 kg ha a 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.
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.
土壤微生物群落及其相关酶活性在陆地生态系统的碳循环中起着关键作用。土壤微生物群落对资源可用性敏感，但微生物调节机制尚未得到充分研究。在此，我们测试了微生物反应与多种相互作用资源之间的机制关系。
我们在中国北方的一个纯人工林中，研究了施氮和去除植物输入（去除凋落物（NL）、根系挖沟和去除凋落物（NRL））条件下的土壤碳特性、土壤微生物群落结构和与碳相关的功能。
我们发现施氮影响土壤微生物群落结构，当添加100 kg ha⁻¹ a的氮时，微生物生物量显著增加。施氮与去除植物输入之间的相互作用显著影响土壤细菌及其酶活性（氧化酶）。NL处理在施氮条件下提高了土壤微生物生物量。我们还发现革兰氏阴性菌和腐生真菌的生物量直接影响与碳周转相关的土壤微生物功能。革兰氏阴性菌的生物量和过氧化物酶活性是控制土壤碳动态的关键因素。施氮与去除植物输入之间的相互作用加强了水解酶与土壤碳之间的相关性。
本研究表明，施氮和去除植物输入可以改变土壤酶活性，并通过微生物调节进一步影响土壤碳周转。在中国北方制定有效的可持续森林管理措施时，需要考虑土壤微生物生物量的增加和土壤碳的微生物调节。此外，还需要进一步研究以确切了解植物与地下过程之间的复杂相互作用如何影响土壤微生物群落结构。
