Remote Sensing Monitoring And Analysis Of Typical Mangrove Nature Reserve In China From 1985 To 2015

Mangrove forest is a woody biotic community with dominant mangrove plants in the intertidal zone of tropical and subtropical regions.As an important ecological wetland and species’ habitat,mangrove wetland plays an irreplaceable role in maintaining and improving the ecological environments of the bays and estuarine areas,preserving from the damages of the storms and surges,preventing the pollutions of the coastal waters and protecting the biological diversity of coastal wetland.From the global perspective,the distribution of mangroves in China is located in the northern edge of the distribution area of mangrove forests in the world.Both the species and the distribution range are representative.Therefore,the mangrove forests in China have the values of studying the origin and evolution of the global mangrove forests.In order to protect the few mangrove forests in our country,our government has been gradually establishing several mangrove reserves in the distribution area of mangrove.However,with the increasing of social economy pressure,the increasing of social economy pressure,the protection effectiveness has been doubted.Therefore,carrying out the study of valuing protection effectiveness in mangrove wetland reserves is of great significance.This paper selects four important areas as the research samples,which of them are Zhangjiangkou Mangrove National Nature Reserve in Fujian province,Zhanjiang Mangrove National Nature Reserve of in Guangdong province,Shankou Mangrove National Nature Reserve in Guangxi province and Dongzhai Harbor National Nature Reserve in Hainan province.Regarding the remote sensing data of Landsat series in 1985,1995,2005,and 2015 as the source data,this paper,firstly,adopts object-oriented classification method to access the data of mangrove area.Then,the quantitative studies of landscape patterns in all reserve areas will be taken by utilizing the landscape index.To be continued,the information entropy model is applied to evaluate the protection effectiveness in all reserve areas.Finally,the above studies are all integrated into analyzing driving forces which influence the protection effectiveness of reserve areas.The results are as follows:(1)During the period from 1985 to 2015,the area of mangrove forests in the Zhangjiangkou and Shankou Mangrove Nature Reserve presented an increasing trend,but the trend was decreasing in Dongzhai Harbor and Zhanjiang Mangrove Nature Reserve.The initial time of mangrove area’s increasing in Shankou Zhanjiang and Zhangjiangkou Mangrove Nature Reserve,basically coincided with the year when the Mangrove Nature Reserve was established.Although Dongzhai Harbor Mangrove Nature Reserve in Hainan was established earlier(in 1980),due to a series of man-made reasons,the area of mangrove has been fluctuating frequently.(2)The landscape index of the mangrove forest in the study area was calculated by the landscape index analysis software,which indicated that compared with 1985,the three nature reserves except for Zhangjiangkou Mangrove Nature Reserve actually made mangrove increase in the aspects of plaque’s quantity,density and figure index in 2015.(3)Based on the changes of the landscape pattern of mangrove forests,the information entropy model was utilized to evaluate the protection effectiveness of mangrove nature reserve in Shankou,Zhanjiang,Zhangjiangkou and Dongzhai Harbor at an interval for 10 years.The results demonstrated that the protection effectiveness of Zhangjiangkou Nature Reserve was stably better than others from 1985 to 2005,however,it was replaced by Zhanjiang Mangrove Nature Reserve from 2005 to 2015.(4)The factors influencing driving forces of the protection effectiveness in reserve areas are divided into natural and human ones.The natural factors contain biological invasion,the rising of sea level,plant diseases and insect pests,and other natural factors,etc.The human factors consist of sea reclamation,implementation of mangrove conservation measures,tourism development,mangrove habitat pollution and over-breeding,etc.,while sea reclamation project is the main effective reason for mangrove forests variation.