The pattern, change and driven factors of vegetation cover in the Qin Mountains region

Chenlu Huang,Yuhan Guo,Linan Guo,Qinke Yang,Yongqiang Zhang

doi:10.1038/s41598-020-75845-5

Abstract

The Qin Mountains region is one of the most important climatic boundaries that divide the North and South of China. This study investigates vegetation covers changes across the Qin Mountains region over the past three decades based on the Landsat-derived Normalized Difference Vegetation Index (NDVI), which were extracted from the Google Earth Engine (GEE). Our results show that the NDVI across the Qin Mountains have increased from 0.624 to 0.776 with annual change rates of 0.0053/a over the past 32 years. Besides, its abrupt point occurred in 2006 and the change rates after this point increased by 0.0094/a (R2 = 0.8159, p < 0.01) (2006–2018), which is higher than that in 1987–1999 and 1999–2006. The mean NDVI have changed in different elevation ranges. The NDVI in the areas below 3300 m increased, such increased is especially most obviously in the cropland. Most of the forest and grassland locate above 3300 m with higher increased rate. Before 2006, the temperature and reference evapotranspiration (PET) were the important driven factors of NDVI change below 3300 m. After afforestation, human activities become important factors that influenced NDVI changes in the low elevation area, but hydro-climatic factors still play an important role in NDVI increase in the higher elevations area.

Highlights

IntroductionDeng analyzed the distribution and change trend of Normalized Difference Vegetation Index (NDVI) in the narrow Qin Mountains (the narrow here means the part of Qin Mountains within Shaanxi Province in China) based on the Moderate Resolution Imaging Spectroradiometer (MODIS) dataset, the results showed that the vegetation cover in narrow Qin Mountains increased significantly from 2000 to 2015, besides, the effect of the influence factor on the change of NDVI in the Qin Mountains is precipitation > temperature > Potential Evapotranspiration[10]
The Qin Mountains region is one of the most important climatic boundaries that divide the North and South of China
Du claimed that vegetation activity in Xinjiang showed an overall increasing tendency over the past three decades during the spring, autumn and summer seasons based on the Global Inventory Monitoring and Modeling System (GIMMS) Normalized Difference Vegetation Index (NDVI) dataset from 1982 to 20122

Summary

Introduction

Deng analyzed the distribution and change trend of NDVI in the narrow Qin Mountains (the narrow here means the part of Qin Mountains within Shaanxi Province in China) based on the MODIS dataset, the results showed that the vegetation cover in narrow Qin Mountains increased significantly from 2000 to 2015, besides, the effect of the influence factor on the change of NDVI in the Qin Mountains is precipitation > temperature > Potential Evapotranspiration[10] These researches still have some insufficiencies because most of them were based on the NDVI derived from GIMMS dataset, which have a long-term available dataset but were conducted only at the coarse resolution level. Questions of this study tries to answer include: (1) when and where have vegetation changes occurs over the past three decades in the Qin Mountains region? and (2) What are the major reasons causing NDVI changes over the past decades in this area?

Methods

Results

Discussion

Conclusion