Light Grazing Significantly Reduces Soil Water Storage in Alpine Grasslands on the Qinghai-Tibet Plateau

Xiaowei Guo,Huakun Zhou,Qian Li,Yangong Du,Guangmin Cao,Dawen Qian,Licong Dai

doi:10.3390/su12062523

Abstract

The degradation of alpine grasslands directly affects their ability to conserve water, but changes in soil water storage in grassland under different degrees of degradation are poorly understood. Here, we selected four grassland plots along a degradation gradient: no-degradation grassland (NG), lightly degraded grassland (LG), moderately degraded grassland (MG) and severely degraded grassland (SG). We then applied an automatic soil moisture monitoring system to study changes in soil water storage processes. Results revealed significant (p < 0.05) differences in soil water storage among NG, LG, MG and SG. Specifically, LG lost 35.9 mm of soil water storage compared with NG, while soil water storage in LG, MG and SG decreased by 24.5%, 32.1% and 36.7%, respectively. The shallow groundwater table, air temperature and grass litter were the key controlling factors of soil water storage in the grassland. Grazing and future global warming will significantly reduce soil water storage in alpine grasslands.

Highlights

With rapid growth of the global population, the freshwater crisis has become a global strategic problem second only to the shortage of oil resources
Grassland degradation causes a series of function degradation in grassland, such as the loss of plant species, soil desertification, the decreasing of above-ground biomass and vegetation coverage and the structural failure of soil aggregates. These grassland environmental factors had an important effect on soil moisture content, so we propose the hypothesis that lightly and moderately degraded grasslands will lose a large proportion of their soil water storage
Grassland degradation had a significant effect on soil moisture content, and the vertical distribution of soil moisture varied among the different degrees of degradation (Figure 2)

Summary

Introduction

With rapid growth of the global population, the freshwater crisis has become a global strategic problem second only to the shortage of oil resources. The Qinghai-Tibet Plateau, as the source of many of China’s and South East Asia’s rivers, is rich in water resources and is called China’s water tower. The region plays an important role in ensuring water security [1]. Alpine grassland is an important basis for water conservation on the Qinghai-Tibet Plateau. Alpine grassland is the most representative vegetation type on the Plateau. Its degradation has a profound impact on China and global ecological security [2,3], thereby generating global interest

Methods

Results

Conclusion