Elevation and Climate Effects on Vegetation Greenness in an Arid Mountain-Basin System of Central Asia

Xiaoli Tai,Bo Li,Howard E Epstein

doi:10.3390/rs12101665

Xiaoli Tai, Bo Li + Show 1 more

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https://doi.org/10.3390/rs12101665

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Journal: Remote sensing	Publication Date: May 22, 2020
Citations: 16	License type: CC BY 4.0

Affiliation: Beijing Normal University, University of Virginia

Abstract

Mountain-basin systems (MBS) in Central Asia are unique and complex ecosystems, wherein their elevation gradients lead to high spatial heterogeneity in vegetation and its response to climate change. Exploring elevation-dependent vegetation greenness variation and the effects of climate factors on vegetation has important theoretical and practical significance for regulating the ecological processes of this system. Based on the MODIS NDVI (remotely sensed normalized difference vegetation index), and observed precipitation and temperature data sets, we analyzed vegetation greenness and climate patterns and dynamics with respect to elevation (300–3600 m) in a typical MBS, in Altay Prefecture, China, during 2000–2017. Results showed that vegetation exhibited a greening (NDVI) trend for the whole region, as well as the mountain, oasis and desert zones, but only the desert zone reached significant level. Vegetation in all elevation bins showed greening, with significant trends at 400–700 m and 2600–3500 m. In summer, lower elevation bins (below 1500 m) had a nonsignificant wetting and warming trend and higher elevation bins had a nonsignificant drying and warming trend. Temperature trend increased with increasing elevation, indicating that warming was stronger at higher elevations. In addition, precipitation had a significantly positive coefficient and temperature a nonsignificant coefficient with NDVI at both regional scale and subregional scale. Our analysis suggests that the regional average could mask or obscure the relationship between climate and vegetation at elevational scale. Vegetation greenness had a positive response to precipitation change in all elevation bins, and had a negative response to temperature change at lower elevations (below 2600 m), and a positive response to temperature change at higher elevations. We observed that vegetation greenness was more sensitive to precipitation than to temperature at lower elevations (below 2700 m), and was more sensitive to temperature at higher elevations.

Highlights

As an important part of ecosystem, vegetation affects land cover, water and carbon cycle, and the near-stratigraphic climate [1,2]
The temperature trend increased with increasing elevation, indicating that warming was stronger at higher elevations
Vegetation greenness was more sensitive to precipitation than to temperature at lower elevations, and more sensitive to temperature at higher elevations

Summary

Introduction

As an important part of ecosystem, vegetation affects land cover, water and carbon cycle, and the near-stratigraphic climate [1,2]. Climate change such as precipitation, temperature and radiation, by changing the energy and water available for plant growth, have an impact on the carbon accumulation process, water cycle process, and soil organic carbon decomposition and conversion process, and affect the growth process and distribution pattern of vegetation [3,4]. The climatic factors affecting vegetation greenness mainly include precipitation temperature and radiation, which vary from place to place [20]. The dominant factor in rainforests is radiation, in arid and semiarid regions is precipitation, and in the high latitudes of the northern hemisphere is temperature [21,22,23]

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