Soil Bacterial Community Responses to N Application and Warming in a Qinghai-Tibetan Plateau Alpine Steppe

Yaoming Li,Zhenzhen Zhao,Jing Zhang,Yuhui Han,Yudan Xu,Shuai Li,Zhiyuan Mu,Shikui Dong,Hao Shen

doi:10.3389/fevo.2021.709518

Abstract

Nitrogen deposition and climate warming can alter soil bacterial communities. However, the response of soil bacteria in an alpine steppe to these changes is largely unknown. In this study, a field experiment was performed on the northeastern Qinghai-Tibetan Plateau to determine the changes in soil bacterial communities of alpine steppes in response to nitrogen application and warming. The experiment consisted of four treatments, namely no-N application with no-warming (CK), N application (8 kg N ha−1 year−1) with no-warming (N), warming with no-N application (W), and N application (8 kg N ha−1 year−1) with warming (W&amp;N). This study aimed to investigate (1) the changes in soil bacterial diversity and community structure under simulated nitrogen deposition and warming conditions, and (2) the key environmental factors responsible for these changes. Based on the results, soil bacterial diversity and community composition did not change significantly in the short term. Warming had a significant effect on overall bacterial composition, rare species composition, and individual bacterial taxa. Besides, the interaction between nitrogen application and warming had a significant effect on community β-diversity. Above-ground plant variables were highly correlated with bacterial community characteristics. Nitrogen application and warming did not significantly alter the distribution range of the bacterial community. Overall, this study suggests that soil bacterial communities can remain relatively stable at the level of simulated nitrogen application and warming and that short-term climatic changes may have no significant impacts on soil bacterial communities.

Highlights

Ecosystems are profoundly affected by an ocean of human activities, including the usage of fossil fuels and changes in land use, resulting in an increased concentration of atmospheric carbon dioxide, increased deposition rates of nitrogen compounds, and increased average temperatures
There were no significant changes in soil pH, moisture, NH4+N, AK, available phosphorus (AP), and total carbon (TC) caused by N addition, warming and their interaction
Warming caused a significant increase in aboveground biomass data (AGB) by 81.37%, but it induced a significant decrease in plant diversity by 28.55%

Summary

Introduction

Ecosystems are profoundly affected by an ocean of human activities, including the usage of fossil fuels and changes in land use, resulting in an increased concentration of atmospheric carbon dioxide, increased deposition rates of nitrogen compounds, and increased average temperatures. The Qinghai-Tibetan Plateau (the QTP), known as the “Third Pole of the Earth,” is highly vulnerable to climate change and considered a “pre-warning region” for the world (Wang et al, 2002). Nitrogen deposition in this region ranges from 8.7 to 13.8 kg N ha−1 yr−1 (Lü and Tian, 2007), whereas warming is about three times the average global warming level of the past 50 years (Qiu, 2008). The response of the soil microbial community to N deposition and warming in QTP grasslands could be used to predict future climate change, the carbon cycle, and ecosystem functions on the Tibetan Plateau

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Conclusion