Ecosystem Service Value and Its Response to Urbanization Based on Different Terrain Gradients in Shannan, Tibet, China

Abstract

Urbanization affects the supply and spatial distribution of ecosystem services by changing the pattern of land use. Studying the spatial response of ecosystem services to urbanization can provide a scientific basis for urban planning and the establishment of ecological protection measures. Shannan Prefecture in the Tibet Autonomous Region is a typical plateau mountainous area with large elevation fluctuations and rich ecosystem types. It is an important ecological barrier in China and even the world. With ArcGIS software, this research used field survey data and statistical data, as well as the remote sensing data in 1990, 1995, 2000, 2005, 2010 and 2015, to analyze the land use pattern changes on different terrain gradients in Shannan, evaluate the spatial pattern of ecosystem service value (ESV) and its temporal and spatial changes on different terrain gradients, and finally analyze the response of ESV to urbanization. The results show that: a. In Shannan Prefecture, build-up lands were mainly distributed in the second and third terrain gradient. With the increase of terrain gradient, the area of farm land and forest land decreased, the area of grassland first in-creased and then decreased, and the area of unused land increased. b. The value of ecosystem services increases first and then decreases with the increase of terrain gradient, reaching the maximum in the third terrain gradient. c. During the study period, the value of ecosystem services showed a downward trend, with a significant decline at the second and third terrain gradient, which indicates that the urbanization has a negative impact on the value of ecosystem services. d. Through quantitative spatial analysis, it is found that urbanization is negatively related to the value of ecosystem services. Ecosystem service value and urbanization showing a high-low clustering effect account for a relatively large amount, more than 30%, mainly concentrated in the low terrain gradient in the southern part of Shannan; low-high clustering effect is mainly distributed in the second and third terrain gradient in the north, where the value of ecosystem services decreases with the increase of the urbanization degree, resulting in a significant agglomeration effect. Our research results offer a guidance for Shannan Prefecture to plan the land use, and optimize the land space and urbanization layout.