| Land is the basic natural resource that is the foundation of humansubsistence and development. Land cover has been changed byunreasonable exploitation and utilization of land resource. During theland eco-environmental evolution, the land system balance has beendestroyed seriously, and ecological function slacked up gradually,which induced the crisis of land eco-environmental security.Tongyu county locates in southwest in the west of Jilin Provinceand agro-pastoral zigzag zone of the Northern China . It has farmingand herd potential. Since the half past century, the eco -environment isworsened continually, the balance of eco-environment is destroyed andthe ecological function is dropped increasingly under the coactions ofnature and human together. All above have led to the increased areasof soda saline land, the seriously degenerated grasslands and the badlyshrunk areas of water and wetland and so on. By now, theeco-environment of Tongyu has been one of the most fragile and worstregions in our country. At the same time, because it is located in thetransition zone between the dry area in inland and the humid area ofsoutheast monsoon climate, its eco-environment system has thefeatures of sensitivity, fragile, mutability. The region is easy to beaffected by global change.On the basis of mentor's subject, the land ecological environmentin Tongyu county was selected as the research object. Several researchaspects were carried on by means of theories and methods ofecological security.Land use/land cover information in Tongyu county was drawnwith 3S integrated technology. Space position was offered with GPS real-timely; GIS was the basic platform, it was used to manage andanalyze space-time data; Space information was offered with RS, andthe datum to GIS was updated in time.Land use and land cover is the most extruded sight sign in thesurface layer on earth, its changes were the result of both naturecondition and human activity, it showed the influence of human to theeco-environment. At first, RS-GIS integration technique was using inthe thesis to land use RS dispelling from 1989 to 200 4 in Tongyu, thedynamic changes of the land use state were taken as a masterstroke tothe study on eco-environment, using the changes of number model, itwas studied that the time and space evolvement course of land use inTongyu, which indicated the leading direction, character and rules ofthe changes progress, and it was the basement of the study oneco-environment evolvement. Based on the analysis of the land usestyles number model, it was concluded that the land use style changesmainly incarnated in the phenomenon of"three increases and threedecreases". Three increases meant the increase of the area of infield,woodland and saline-alkali soil. Three decreases meant the decrease ofthe area of grassland, water area and marsh. Thereinto the mostincreasing area is woodland, the area of saline-alkali soil is less;contrary the most decreasing area is grassland, the area of marsh is less.The result of both nature condition and human activity lead to thechange of land-use fashion in different aspects and different rates.Interactional transforms take place in all kinds of land -use style. It isproved that the increasing of infield and saline -alkali soil costs thedecreasing of grassland and marsh. The degradation of grassland andthe increase of saline-alkali soil gave great effect to the degradation ofeco-environment in the study area.During the evaluation of land ecological environment security,with the aid of the space analyses function of GIS , territory range ofTongyu county was divided by village evaluation units. From the viewpoint of systematic pressure, state and response, the index systemwas design according to AHP. With the model of fuzzy syntheticalevaluated method, the evaluation of land ecological environmentalsecurity in the west of Jilin province in 2004 was carried on throughDPS software program. The result of evaluation was represented in theform of digital picture. The result indicated that the land ecologicalenvironment in Tongyu county was in the unsafe state generally.Then, according to the result of land ecological environmentsecurity evaluation, Tongyu county was carried on the land ecologicalenvironment precaution research. According to the principle andcourse of precaution, on the basis of analyzing current land ecolog icalenvironment situation of Tongyu, the precaution research of landecological environment in 2010 was carried on by using the greyprediction models. The research contained five parts: defining themeaning of alert, looking for the alert source, analyzing the indicationof alert, predicting alert degree and getting rid of the hidden trouble.The result indicated that land ecological environment of Tongyucounty had already in the dangerous state in 2010. To this variationtendency, the concrete guarantee measures of the land ecologicalenvironment security were proposed.Based on the soil data investigated all over the country in 1978and 1992, carbon density data from IPCC and space informationdrawn with 3S integrated technology, carbon storage in Tongy u countyin 1989,2000and 2004 was calculated. It is found that, the carbonstorage is decreased in Tongyu county before 2000 and increased after2000. The policy of environmental protection is brought into effectfrom 2001, which induce the good change of land ecological security.Finally. The research of land utilization optimization in Tongyu countyis achieved by linearity programming. The target value is balance ofcarbon storage, and the requirement of farmland is considered.Using the technique integration of RS-GIS-GPS, adoptingmulti-source RS or non-RS data, the dynamic study was done on land resources and eco-environment in Tongyu from different time, allaround space, and various scales. The research which related toeco-environment study method had spread and reference value to theother cities or counties in Jilin Province. |
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