Abstract
Drought and vegetation dynamics in the northern Xinjiang Uygur Autonomous Region of China (NXC), the centre of Asia with arid climate, were assessed using the standardized precipitation evapotranspiration index (SPEI) and the normalized difference vegetation index (NDVI). Analyses were performed through the use of Sen’s method and Spearman’s correlation to investigate variations in the NDVI and the impacts of drought on vegetation from 1998 to 2015. The severity of droughts in the NXC was assessed by the SPEI, which was revealed to increase over the last 60 years at a rate of 0.017 per decade. This indicates that an alleviating tendency of drought intensity occurred in the NXC. Specifically, the spatial pattern of drought intensity increased gradually from the north-western to south-eastern regions. The average yearly NDVI was 0.28 and increased slightly by 0.001 yr−1 (r = 0.94, p = 3.64) between 1998 and 2015. Additionally, the NDVI showed an obviously spatial heterogeneity, with greater values in the west and small values in the east. Significantly, positive correlations between SPEI and NDVI were observed, while drought exerted a five-year lag effect on vegetation.
Highlights
The impact of worldwide climate change has led to changes in terrestrial ecosystems, of which vegetation is a fundamental element and forms a core component of the soil–vegetation–atmosphere continuum
Various studies have proven the sensitivity of vegetation in various regions of the world to environmental changes [1], where vegetation dynamics are significantly affected by climate change, in the arid zone
Applying Sen’s slope estimation, the annual standardized precipitation evapotranspiration index (SPEI) increased at a linear rate of 0.017yr−1 (p < 0.01), and shows a significance level of α = 0.05 based on the M–K test (Figure 2b).The lower the SPEI was, the heavier the drought occurrence was; that is, an increasing trend of SPEI indicates that drought occurrence has been decreasing
Summary
The impact of worldwide climate change has led to changes in terrestrial ecosystems, of which vegetation is a fundamental element and forms a core component of the soil–vegetation–atmosphere continuum. Various studies have proven the sensitivity of vegetation in various regions of the world to environmental changes [1], where vegetation dynamics are significantly affected by climate change, in the arid zone. The investigation and examination of dynamic vegetation changes and the major drivers for such changes has an important significance in the understanding of the response mechanism and managing regional ecosystems [2,3]. Previous studies have shown that the climate warming was not occurred only at the global scale, and in regional scale. To the arid zone, the implications of environmental changes on regional vegetation is complex due to the spatiotemporal variations in such changes and eco-environmental circumstances [11,12,13]
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