Assessment Of Ecological Environment And Monitoring Of Typhoon Disturbance Area Forest Restoration In Changbai Mountain Nature Reserve

The well-being of human race is closely related to the ecological environment,while regional ecological environment management,improvement and development planning can not be separated from the support of eco-environmental quality evaluation.Recently,indicators retrieved from remote sensing data has been increasingly applied to ecological environment quality evaluation for advantages of spatial visualization,and the remote sensing technology can offer iaportant reference to regional ecological environment management,improvement and development planning by quickly assessing regional ecological environment quality.In this paper,Landsat 5 TM images in 1995 and 2007 and Landsat 8 OLI images in 20l5were used as data source to retrieve values of the four indicators including green degree,humidity degree,heat degree and dry degree which can reflect ecological environment status to construct RSE1 with the principal component analysis method,and Changbai Mountain Nature Reserve ecological environment quality from 1995 to 2015 was evaluated using RSEI.The change detection of RSEI classes were used as the transition probability matrix for CA-Markov model to predict the development of ecological environment quality.The result showed:(1)The green degree and humidity degree have an positive effect on promoting the ecological environment quality of the region while the heat degree and dry degree have a restraining effect on the regional ecological environment quality,and the humidity degree is the more significant than other three indicators.(2)In this region,the proportion of excellent and good RSEI classes accountedfor49.520%、66.508%and76.189%of the total areain 1995,2007 and 2015.Meanwhile,the degenerated,unchanged and improved RSEI classes were3.945%、55.598%and 40.457%of the total area respectively,indicating that the overall ecological environment quality has gradually improved.To some extent,this is attributed to the Natural Forest Resources Protection Project and a series of ecological conservation measures taken in the Changbai Mountain Nature Reserve.Although the overall ecological environment quality of the study area has gradually iaproved,the eeological environment quality around Tianchi has declined,this area has a relatively fragile ecological environment and suffers from high intense tourism activities.(3)The Stepwise regression analysis results verify the rationality of constructing the indicators of RSEI and the model prediction result reveals that the control of barren and dry surfaces is a critical step for improving the ecological environment quality.(4)Based on the method of Iand use/cover change,the RSEI class of different periods were used as the transition probability matrix for CA-Markov model.First,compared the predicted RESI and actual calculated RSEI in 2015,the Kappa value is 86.98%,which indicates that this method can be used to forecast the ecological environment quality.Then,RSEI in 2007 and 2015 were used to forecast RSEI situation in 2023,the results shows that the number of bad and comparatively bad class pixels were reduced by 33,800,indicating that the eco-environmental quality is gradually improved.Changbai Mountain Nature Reserve is dominated by forests,while the forests of the west slope and the southern slope are interfered with by typhoons.Therefore,the forest of typhoon disturbance areas is selected for restoration and monitoring.First,the typhoon disturbance area was extracted by combining the land cover types with the DI difference between 1987 and 1985,then DI time series data from 1986 to 2016 were used to analyze forest restoration dynamic situation of typhoon disturbance area.Finally,the time needed for the forest to recover to the level before disturbance was calculated according to the average change rate of forest recovery.The main conclusions are as follows:(1)The DI index has significantly differences before and after the typhoon disaster.The threshold method was used to divide the area which with the maximum difference in 1987 and 1985,and the range of the typhoon disturbance area was extracted combined with land cover types,which covering an area of 125.1 km2.The area of the typhoon disturbance area extracted by this method is close to that of Nanying et al.,Which is higher than the actual measured area of Changbai Mountain Nature Reserve.The remote sensing is superior to manpower investigation in identifying complex terrain and smaller disturbance area.(2)From the mean of DI in the typhoon disturbance area,two fluctuations were observed in 2000 and 2007,and then showed a relatively stable downward trend,but still not restored to the level before typhoon disturbed.From the space,the western slope is better recovered,mainly for mld disturbance,which is close to the normal level.The southern slope is mainly moderate and mild disturbance,with less type of recovery,but less severe disturbance and severe disturbance.(3)Using the slope of the unitary linear regression equation,the average rate of change of DI over 1993-2016 is calculated.The time needed for the forest to recover to the level of 1985 was obtained based on the average change rate.Overall,the forest in typhoon disturbance area has been significantly restored,the forest in the western slope is in good restoration,while the forest in the southern slope still need another 30-50 years to recover to the normal level.The dynamic information of forest restoration can provide guidance for the development of forest ecological conservation measures and the management of forest in typhoon disturbance area.