Dynamic changes and driving force in Jingxin wetlands at the lower reaches of Tumen River Area

With the technical support of geographic information systems and remote sensing,data of topographic maps,Corona images,TM images,Alos images,and the wetland information of the lower reaches of Tumen River from the year of 1960,1986 and 2009,analysised the distribution,landscape pattern,and changes of these wetlands for the last 50 years.The results showed that 1) The man-made wetlands,including paddy fields and reservoirs increased significantly.However,the natural wetlands,including swamps,lakes and rivers,decrease consistently through the years.2) Based on the changing characteristics of the wetland types,a large number of natural wetlands change into man-made wetlands and non-wetlands,whereas a large number of non-wetlands change into paddy fields.3) Based on the change in wetland landscape patterns,there is an increase in the number of landscape patches and the values of the landscape fragmentation index and the landscape evenness index.However,the average patch areas and the landscape diversity index decrease.4) Human factors are the main driving forces causing the reduction of natural wetlands in this area.Among these human factors,agricultural activities have the most significant effect.