Search

Habitat change of coastal wetlands caused by natural and anthropogenic factors is an important issue facing China. Large areas of coastal habitat are disappearing, and those remaining become vulnerable to anthropogenic impacts from industry, agriculture, aquaculture, urban development, and domestic waste. A question is whether the change of habitat area has an influence on boundary adjustments of natural reserves. The study reported in this paper applied remotesensing images, and environmental and socioeconomic data to analyse the change of land use and land cover and habitat quality in an estuarine area and to identify the driving forces for these changes from 1988 to 2008. The results show that land use has changed significantly over this period. Cultivated lands occupying total area 35.96% decreased from 36,879.0 ha to 35,313.7 ha from 1988 to 1999. The area of settlements expanded from 11,305.1 ha in 1988 to 16,661.3 ha in 1999 and further to 23,258.6 ha in 2008. The areas of settlement, saltwater bodies, and unused land increased by 47.38%, 33.51%, and 16.66%, respectively, from 1988 to 1999. These trends continued from 1999 to 2008. The total average biomass in 2003 was far below the biomass of the same region in 1983 and the biological density also decreased sharply. The gross domestic product and population of the Dagang District grew continuously from 1993 to 2006 and was the main driving force of habitat change. The habitat quality of coastal wetlands is associated with natural reserve boundaries, which should be modified according to the actual protection status. The suggestion of boundary adjustment has also assisted the enhancement of habitat quality of coastal wetlands. This research emphasises the improvement of coastal environments through implementation of boundary adjustments. [ABSTRACT FROM AUTHOR]

Seagrass distribution is a very important index for costal management and protection. Seagrass distribution changes can be used as indexes to analyze the reasons for the changes. In this paper, in situ hyperspectral observation and satellite images of QuickBird, CBERS (China Brazil Earth Resources Satellite data) and Landsat data were used to retrieve bio-optical models and seagrass (Enhalus acoroides, Thalassia hemperichii) distribution in Xincun Bay, Hainan province, and seagrass distribution changes from 1991 to 2006 were analyzed. Hyperspectral results showed that the spectral bands at 555, 635, 650 and 675 nm are sensitive to leaf area index (LAI). Seagrass detection with QuickBird was more accurate than that with Landsat TM and CBERS; five classes could be classified clearly and used as correction for seagrass remote sensing data from Landsat TM and CBERS. In order to better describe seagrass distribution changes, the seagrass distribution area was divided as three regions: region A connected with region B in 1991, however it separated in 1999 and was wholly separated in 2001; seagrass in region C shrank gradually and could not be detected in 2006. Analysis of the reasons for seagrass reduction indicated it was mainly affected by aquaculture and typhoons and in recent years, by land use changes. [ABSTRACT FROM AUTHOR]