Ecosystem Health Assessment Based on Terrain Gradients and Its Response to Urbanization in Shannan, Tibet, China

Abstract

Urbanization has an important impact on ecosystem health (ESH) by affecting land use patterns and ecosystem processes and services. Evaluating the spatial correlation between ESH and urbanization is helpful to analyze the impact of urbanization on ecosystem, and also provides a new perspective and scientific basis for rational and scientific ecosystem protection and management. In this study, we took Shannan Prefecture in the Tibet Autonomous Region as an example to establish an ecosystem health evaluation index system, and evaluated the ecosystem health on different terrain gradients by using Remote Sensing (RS) and the Geographic Information System (GIS) processing tools in 1990, 1995, 2000, 2005, 2010 and 2015. The results show that Shannan’s ecosystem was in good health, mainly in Ave-health and Highest Health levels from 1990 to 2015. During 1990 to 2015, the ecosystem area of the highest health level increased by 0.68%, while the area of Degraded level decreased by 1.51%. This research showed that the ecosystem health in Shannan got better from 1990 to 2015. The area of Highest Health decreased with an increase in the terrain gradient, which were affected by natural environment. In the third terrain gradient with rapid urbanization, the areas of Highest Health, Sub-Health, and Ave-health decreased while the areas of Degraded and Unhealthy increased. This indicated the urban sprawl cause decline in ecosystem health. After further analyzing the response of ecosystem health to urbanization, it is found that ecosystem health is negatively related to urbanization. According to analysis of spatial correlation, we found Low-High type of ecosystem health and urbanization is obviously concentrated in the north of Shannan City where with high-population and urbanization. This result can be used as a guidance for Shannan Prefecture to rationally plan the urbanization process on the basis of the continuous protection and improvement of ecosystem health, and at the same time, through policy innovation, the ecosystem health can be transformed into an advantage for economic development.