Assessment of ecological conditions over China's coastal areas based on land use/cover change.

Studying the changes of land use and its impacts on ecological condition in coastal areas is of great significance for understanding the evolution of the regional ecological conditions and even global change. In this study, the study area encompassed 10 provincial administrative units of China's coastal areas, covering a total of 56 cities. Based on the land use and land cover data in 1980, 1990, 1995, 2000, 2005, 2010 and 2015 and the corresponding elevation data, we assessed ecological conditions and its temporal dynamic evolution and spatial differentiation characteristics with the ecological grade index method. The effects of the elevation differentiation and land-sea gradient on the ecological condition in China's coastal areas were analyzed. The results showed that the ecological conditions of China's coastal areas were basically stable and deteriorated on the whole although partially improved from 1980 to 2015. With Hangzhou Bay as a boundary-belt, ecological conditions in southern parts were better than that in the northern parts. The ecological grade index differed significantly with the variation of elevation. The areas with elevation below 10 m were in rela-tively poor ecological condition, and the regions below 30 m had the most obvious changes of ecological conditions. Moreover, the ecological conditions increased with elevation, with a gradual turnaround trend of improvement at above 400 m. There was a gradient characteristic of the ecological grade index in China's coastal areas, showing a high-low-high pattern from land to sea. Furthermore, the maximum value of ecological condition changes appeared at a distance of 10 km to the coastline, and the values decreased with the increasing of distance to the coastline.