Analysis of the dynamic change characteristics of forest land, grassland and wetland in Xichang City from 1989 to 2018

Remote sensing technology has been widely used in ecological environment investigation and research. In order to obtain the evolution trend of ecological environment in Xichang City in recent 30 years, the authors in this research used TM (Thermal Mapper) remote sensing images in 1989, 2000 and 2010 and OLI (Operational Land Imager) remote sensing images in 2018 to acquire the landuse/cover data of Xichang City from 1989 to 2018 and investigate the dynamic change characteristics of forest land, grassland and wetland, through image processing, visual interpretation and field verification. The results show that the area of forest land, wetland and grassland in Xichang City continued to increase from 1989 to 2018, which indicated the improved ecological environment. The forest land is mainly distributed in Anning River Valley and the mountains around Qionghai Lake Basin, and the main forest areas are formed in the areas of Maoniu Mountain and Luoji Mountain. The grassland is mainly distributed in the area of Maoniu Mountain and Luoji Mountain in the forest area, and the wetland is mainly river wetland and lake wetland, mainly distributed along Anning River and Qionghai Lake. However, there still exist some unsolved problems. The coniferous phenomenon is widespread in the forest and the tree species aren’t rich, and the fire prevention should be strengthened in forest area. The grassland is distributed sporadically, without comprehensive system structure and geod quality function. Most of the grassland with low productivity is not suitable for extensive construction and should be converted to forest by closing hillsides for afforestation. The wetland has limited distribution, which need excessive protection. The research results of this paper can provide a scientific basis for the formulation of ecological protection and restoration measures and the sustainable development of economy and society in Xichang City.