Effects of Elevation and Distance from Highway on the Abundance and Community Structure of Bacteria in Soil along Qinghai-Tibet Highway.

Zhuocheng Liu,Liebao Han,Mengdi Wang,Shuangxuan Ji,Di Dong,Xueping Chen,Yangang Yang,Yinruizhi Li

doi:10.3390/ijerph182413137

Abstract

In recent years, highway construction in the Qinghai-Tibet Plateau (QTP) has developed rapidly. When the highway passes through grassland, the soil, vegetation, and ecological environment along the line are disturbed. However, the impact on soil bacteria is still unclear. Soil bacteria play an important role in the ecological environment. The Qinghai-Tibet Highway (QTH) was selected as the research object to explore the changes in bacterial community structure, vegetation, soil, and other indicators. The results showed that the highway-related activities increased the degradation of vegetation along the road, significantly changed the physical and chemical properties of soil, and caused heavy metal pollution. These environmental factors affected the diversity and community structure of soil bacteria. This kind of disturbance shows a trend of gradually increasing from near to far from the highway. Gemmatimonas, Terrimonas, Nitrospira and Bacillus are more tolerant to environmental changes along the highway, while Barnesiella, and Blastococcus are more sensitive. The content of nitrate decreased and the content of ammonium nitrogen increased in the disturbed area, increasing the abundance of nitrifying bacteria. Therefore, the main factor of the disturbance of the QTH on the grassland is the decline of soil nutrient content, and the supplement of soil nutrients such as carbon and nitrogen should be taken into account in the process of ecological restoration of grassland along the line.

Highlights

As the highest geographical unit in the world, the Qinghai-Tibet Plateau (QTP) has a particular and representative ecological environment
The results showed that: (1) The soil bacterial community structure changes with the distance from the Qinghai-Tibet Highway (QTH); (2) In high altitude areas, the soil bacterial community is more susceptible to highway impacts; (3) Soil nutrients are the main driving factor of soil bacterial community structure change; (4) Within a certain distance from the QTH, the heavy metal content was correlated with soil bacterial community diversity
Gemmatimonas was positively correlated with Zn (p < 0.05) and negatively correlated with Soil organic carbon (SOC) (p < 0.01). These results show that soil properties, especially SOC, total nitrogen (TN), alkali-hydrolyzable nitrogen (AN), AK, soil moisture (SM), pH, Cu, and Zn have significant effects on soil bacterial communities

Summary

Introduction

As the highest geographical unit in the world, the Qinghai-Tibet Plateau (QTP) has a particular and representative ecological environment. With the rapid economic development of the Qinghai-Tibet region, road transportation has continued to develop [7,8]. Tibet Autonomous Region increased from 15,852 km in 1978 to 117,000 km in 2021 [9]. Highway traffic inevitably disturbs natural grasslands and has a series of negative influences on the ecosystem, including soil erosion, vegetation destruction, and water quality deterioration [10,11,12,13]. The sharp increase in negative impacts has resulted in imbalances in the self-regulation of the grassland ecosystem, and varying degrees of degradation of grasslands along highways [14]

Methods

Results

Discussion

Conclusion