Comprehensive Grassland Degradation Monitoring by Remote Sensing in Xilinhot, Inner Mongolia, China

Xin Lyu,Xiaobing Li,Hong Wang,Jirui Gong,Siyu Liu,Dongliang Dang,Huashun Dou,Shengkun Li

doi:10.3390/su12093682

Abstract

Grassland degradation is a complex process and cannot be thoroughly measured by a single indicator, such as fractional vegetation cover (FVC), aboveground biomass (AGB), or net primary production (NPP), or by a simple combination of these indicators. In this research, we combined measured data with vegetation and soil characteristics to establish a set of standards applicable to the monitoring of regional grassland degradation by remote sensing. We selected indicators and set their thresholds with full consideration given to vegetation structure and function. We optimized the indicator simulation, based on which grassland degradation in the study area during 2014–2018 was comprehensively evaluated. We used the feeding intensity of herbivores to represent the grazing intensity. We analyzed the effects of climate and grazing activities on grassland degradation using the constraint line method. The results showed degradation in approximately 69% of the grassland in the study area and an overall continued recovery of the degraded grassland from 2014 to 2018. We did not identify any significant correlation between temperature and grassland degradation. The increase in precipitation promoted the recovery of degraded grassland, whereas increased grazing may have aggravated degradation. Our findings can not only improve the scientific quality and accuracy of grassland degradation monitoring by remote sensing but also provide clear spatial information and decision-making help in sustainable management of grassland regions.

Highlights

Grassland plays a key role in the supply of ecosystem services (ES) for human society, which provide provision services and provide regulation and support services such as climate regulation, soil conservation, wind protection and sand fixation, water conservation, as well as cultural services such as recreation [1,2]
About 69% of grassland in the study area showed variable degrees of degradation
We developed a set of standards for the remote-sensing monitoring of regional-scale grassland degradation on the basis of vegetation and soil characteristics

Summary

Introduction

Grassland plays a key role in the supply of ecosystem services (ES) for human society, which provide provision services (e.g., meat, milk) and provide regulation and support services such as climate regulation, soil conservation, wind protection and sand fixation, water conservation, as well as cultural services such as recreation [1,2]. Its continued degradation will negatively affect productivity and result in the deterioration of grassland ecosystem functioning and affect the circulation of trace elements [3,4]. At present, it is an impending issue for enhancing grassland management, identifying the mechanism of grassland productivity decline, and uncovering the pattern of grassland ecosystem service functions. Selecting an appropriate evaluation index is a prerequisite in grassland degradation monitoring by remote sensing and is the basis for establishing related standards. Zhou et al evaluated the degradation dynamics of grassland in China in 1982–2010 with NPP and grass coverage as the main indicators [10]. Using hyperspectral data to simulate FVC, Wiesmair et al assessed the degree of grassland degradation in the study area and proposed suggestions for grassland management [11]

Objectives

Methods

Results

Discussion

Conclusion