Intensity Change of Human Disturbance and Its Response to Landscape Pattern in the Yellow River Delta

The coastal wetlands of the Yellow River Delta is the most integral, broadest and youngest wetland ecosystem in the warm temperate zone of China. Also, it has unique ecological landscape as well as important ecological service functions. With the increase in population and the intensification of high- intensity development and construction activities, the sensitivity/fragility of the area is highlighted, which poses a great threat to the sustainable development of coastal areas. Aiming at the unique geographic location and resource characteristics of the Yellow River Delta, based on RS and GIS, the hemeroby model as well as the man-made ditches density were used in this study to intuitively reveal the temporal and spatial characteristics of human disturbance intensity in 1995,2004 and 2015 at the regional and local scales. The response of the wetland landscape pattern to human interference activities was explored as well. A grid analysis method was used to calculate the hemeroby index and man- made ditches density. The data source included the following: Landsat TM、ETM~+ and OLI Remote Sensing Data (30 m resolution) in 1995、2004、2015, SPOT image of 2004(5m resolution), GF-1 image of 2015 (2 m resolution) and topographic map. This study aims to provide decision support for ecological regulation and spatial control on human activities in coastal wetlands of the Yellow River Delta. The results showed that: (1) From 1995 to 2015,both the hemeroby index and the density of artificial ditches in the Yellow River Delta had increased significantly, and its spatial distribution showed a trend of expansion from the southwest to the east and north, and from inland to coastal areas; (2) With the increase of human activities, the area of natural wetlands in the study area have been decreased from 3232.11km~2 in 1995 to 2165.48km2 in 2015,the landscape diversity and spatial heterogeneity increased, ecological connectivity weakened, the plaque shape tended to be regular and simplistic. (3) The response of landscape pattern to hemeroby index varies regionally and temporally. In the Kenli Agricultural Area, Hekou Agricultural Area and Shengli Oil Field Area, where the intensity of human interference activities had been relatively high, the intensity increased significantly, and the regional landscape pattern changed obviously in different phases. In the Yiqianer Management Station and the Yellow River Estuary Management Station area, where the intensity of human interference activities had been relatively low, due to the increase in the density of artificial ditches, the landscape pattern had presented a decreasing trend in landscape diversity, patch complexity and ecological connectivity from 2004 to 2015. (4) The indices of hemeroby and the density of man-made ditches supplement each other and confirm each other, which can reflect the degree of human disturbance activities in the Yellow River Delta more comprehensively and objectively