Study on land use change of Dajiu lake and its impact on ecological environment in the last 60 years
Dajiu lake of Shennongjia is a typical,unique and rare subalpine peat-swamp wetland in China.From 1985 to 2002,due to the building of farms,the area of Dajiu lake had been transformed from wetlands to farmlands,for example,transforming natural river channels,straightening curved river sections,building north-south main canals,draining water in wetlands,cultivating croplands in a large amount to expand the farmland area,and growing high-altitude vegetables.With China increasingly giving priority to ecological conservation,the government of Shennongjia Forestry District established the Nature Reserve of Dajiu Lake Wetland at a district level in December 2003,initiating the protection of ecological environment in Dajiu lake.During this period,the ecological environment in the area of Dajiu lake,especially the center of this area,underwent a dramatic transition from extensive development to large-scale conservation.In order to fully understand the change in the ecological environment of Dajiu lake before and after large-scale development and conservation,the center of Dajiu Lake National Wetland Park was selected as the study area.Keyhole satellite data,Landsat7 ETM data,and unmanned aerial vehicle images from 1963,2002,and 2021,respectively representing the undeveloped period,development period,and protection period of Dajiu lake,were compared to analyze changes in land use and in ecological environment quality within the study area during the three time periods.Research results show that during the primitive agricultural period in the area of Dajiu lake,wetlands and grasslands covered the largest area of total land use,with less land used for construction,resulting in a relatively better ecological environment.However,during the period of large-scale agricultural development,a significant number of grasslands and wetlands were converted into arable lands.With a sharp increase of arable lands and human activities,the ecological environment suffered considerable damage.After implementing large-scale ecological environment protection in the area of Dajiu lake,initiatives such as returning cropland back to grasslands and wetlands contributed to a significant recovery of grasslands and wetlands,a notable increase in water body area,and a considerable improvement of ecological environment.The index of regional ecological environment quality was determined based on the land use transfer matrix data about the area of Dajiu lake from 1963 to 2002.The results indicate that the index of regional ecological environment quality in the study area decreased from 0.601 in 1963 to 0.473 in 2002,but rose to 0.651 in 2021.This shows that over the past 60 years,the overall ecological environment quality in the study area has exhibited a pattern of an increase after an initial decrease,with a sustained improvement in the overall ecological environment after 2002.The quality of ecological environment during the protection period surpassed that of the large-scale development period and was better than that in the undeveloped period,which demonstrated significant achievements in the 18-year protection of ecological environment in the area of Dajiu lake.This study analyzed in detail the driving forces behind the changes in the ecological environment quality of the study area,explored the specific reasons for and predicted the trends of changes in land use and ecological environment quality.Remote sensing interpretation of land use changes in the area of Dajiu lake was generally based on remote sensing data after 2000.In the remote sensing interpretation of this study,the time of historical data was advanced to 1963,which extended the time span of land use changes in Dajiu lake to over 60 years from more than 20 years,longer than that in previous studies.
国家科技期刊平台
NSTL
万方数据
