Changes in NDVI and human population in protected areas on the Tibetan Plateau

Yongkang Xue,Thomas W Gillespie,Austin Madson,Conor F Cusack

doi:10.1080/15230430.2019.1650541

Abstract

ABSTRACTUnderstanding the Tibetan Plateau’s role in environmental change has gained increasing scientific attention in light of warming and changes in land management. We examine changes in greenness over the Tibetan Plateau using the Normalized Difference Vegetation Index (NDVI) from the Global Inventory Monitoring and Modeling Study (GIMMS3g) to identify significant changes over the entire plateau, six ecoregions, and protected areas based on a multiyear time series of July imagery from 1982 to 2015. We also test whether there have been changes in human populations in protected areas. There has been relatively little change in mean NDVI over the Tibetan Plateau or ecoregions, however, there were significant changes at the pixel level. There are sixty-nine protected areas on the Tibetan Plateau; sixty-two protected areas had no significant change in mean NDVI and seven protected areas experienced a significant increase in NDVI. There has been an increase in population within protected areas from 2000 to 2015; however, mean populations significantly increased in two protected areas and significantly decreased in four protected areas. Results suggest a slow greening of the Tibetan Plateau, ecoregions, and protected areas, with a more rapid greening in northern Tibet at the pixel level. Most protected areas are experiencing minor changes in NDVI independent of human population.

Highlights

In the twenty-first century, understanding the Tibetan Plateau’s role in the global climate and environmental change has gained increasing scientific attention in light of global warming (Cui and Graf 2009; Zhu et al 2016)
Vegetation change has been monitored from the Moderate Resolution Imaging Spectroradiometer (MODIS) and Advanced Very High Resolution Radiometer (AVHRR) sensors using the Normalized Difference Vegetation Index (NDVI), which is calculated as a function of the visible and near-infrared wavelengths
There were no significant changes in mean NDVI over ecoregions based on GIMMS3g.v1

Summary

Introduction

In the twenty-first century, understanding the Tibetan Plateau’s role in the global climate and environmental change has gained increasing scientific attention in light of global warming (Cui and Graf 2009; Zhu et al 2016). Since 2001, a number of studies have noted that there has been a significant warming trend over the Tibetan Plateau, and this may have impacted the productivity of vegetation on the Tibetan Plateau (Wang et al 2008; Peng et al 2012; Zhu et al 2016). Climatic changes have been hypothesized as the cause of increased greening of the Qinghai–Tibet Plateau (Sun et al 2013; Zhu et al 2016). From 1982 to 2003, annual greenness based on NDVI from AVHRR showed increases on the Tibetan Plateau, especially for shrublands, meadows, grasslands, and deserts (Peng et al 2012). AVHRR and MODIS have shown decreasing greenness during the growing season from 2000 to 2010, especially in the southwest area of Supplemental data for this article can be accessed on the publisher’s website

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Conclusion