Ecological Effects of Grazing in the Northern Tianshan Mountains

Xiaotao Huang,Tureniguli Amuti,Xinxin Wang,Geping Luo,Huili He

doi:10.3390/w9120932

Abstract

Identifying the effects of grazing is critical for the conservation, protection and sustainable use of arid grassland ecosystems. However, research regarding the ecological effects of grazing along mountainous elevation gradients is limited in arid areas, particularly at the regional scale. Using the Biome-BGC grazing model, we explored the effects of grazing on grassland net primary productivity (NPP), evapotranspiration (ET) and water use efficiency (WUE) from 1979 to 2012 along an elevation gradient in the northern Tianshan Mountains. The NPP, ET and WUE values were generally lower under the grazing scenario than under the ungrazed scenario; the differences between the grazing and ungrazed scenarios showed increasing trends over time; and distinct spatial heterogeneity in these differences was observed. Distinct decreases in NPP and WUE under the grazing scenario mainly occurred in regions with high livestock consumption. The decrease in ET was greater in mountainous areas with high grazing intensity due to decreased transpiration and increased surface runoff. This study contributes to a better understanding of the ecological effects of grazing along an elevation gradient in the northern Tianshan Mountains and provides data to support the scientific management of grassland ecosystems.

Highlights

Grassland ecosystems serve important economic and ecological functions, such as material production, climate regulation, soil and water conservation, sand stabilization, soil improvement and biodiversity preservation [1,2,3]
In this study, using the Biome-BGC grazing model and selecting the northern Tianshan Mountains as a study area, we address the effects of grazing on grassland net primary productivity (NPP), ET and water use efficiency (WUE) at a regional scale from 1979 to 2012
Where Dr (gC/(ha d)) is the defoliation rate that represents carbon consumed by animals; Ge is the grazing efficiency of the livestock; Sr is the grazing intensity; Cleaf is the C in the leaf biomass; (Cleaf )U is the residual aboveground Cleaf that is unavailable to livestock; and Dx is the consumption rate of the livestock based on satiation (gC/(d head))

Summary

Introduction

Grassland ecosystems serve important economic and ecological functions, such as material production, climate regulation, soil and water conservation, sand stabilization, soil improvement and biodiversity preservation [1,2,3]. Grassland ecosystems are susceptible to disturbances and highly vulnerable to climate change and human activities, in arid areas [4,5,6,7]. Due to a lack of water resources and complex human activities, ecological processes in arid grasslands may be different from those in humid areas [8]. Grassland ecosystems in arid areas have become the focus of numerous studies. The northern Tianshan Mountains are located in an arid region of central Asia with widely distributed and diverse grassland ecosystems.

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Methods

Results

Discussion

Conclusion