The Assessment Of Land Ecosystem Health

Land is the basic natural resource that is the foundation of human subsistence and development. Land cover has been changed by unreasonable exploitation and utilization of land resource. During the land eco-environmental evolution, the land system balance has been destroyed seriously, and ecological function slacked up gradually, which induced the crisis of land ecosystem health.Tongyu county locates in southwest in the west of Jilin Province and agro-pastoral zigzag zone of the Northern China. It has farming and herd potential. Since the half past century, the eco-environment is worsened continually, the balance of eco-environment is destroyed and the ecological function is dropped increasingly under the coactions of nature and human together. All above have led to the increased areas of soda saline land, the seriously degenerated grasslands and the badly shrunk areas of water and wetland and so on. By now, the eco-environment of Tongyu has been one of the most fragile and worst regions in our country.At the same time, because it is located in the transition zone between the dry area in inland and the humid area of southeast monsoon climate, its eco-environment system has the features of sensitivity, fragile, mutability. The region is easy to be affected by global change. The actuality and transformation of environment in Tongyu county was analysed, and the land ecosystem health assessment was accomplished, which was representative of environmental evolvement in songnen plain. On the base of land-use/land -cover analyse, remote sesing data and non-remote sesing daya was applied to analyze the dynamics land-use/land–cover change, which improved precision of land ecosystem health assessment. Based on the character of soil desertification and land saltification, as well as the anlyse of landscape change, from the viewpoint of systematic pressure, state and response, the index system was design, which was representative in the study of land ecosystem health in dry and semiarid area.A large amount of remote sesing data, land use/land cover data, fieldwork data and other correlational data was accumulated in prof.Tang Jie's scientific research group. The land use changes was combined with land ecosystem evolvement to assess the land ecosystem health. Several research aspects were carried on by means of theories and methods of ecosystem health.Land use/land cover information in Tongyu county was drawn with 3S integrated technology. Space position was offered with GPS real-timely; GIS was the basic platform, it was used to manage and analyze space-time data; Space information was offered with RS, and the datum to GIS was updated in time.Land use and land cover is the most extruded sight sign in the surface layer on earth, its changes were the result of both nature condition and human activity, it showed the influence of human to the eco-environment. At first, RS-GIS integration technique was using in the thesis to land use RS dispelling from 1989 to 2004 in Tongyu, the dynamic changes of the land use state were taken as a masterstroke to the study on eco-environment, using the changes of number model, it was studied that the time and space evolvement course of land use in Tongyu, which indicated the leading direction, character and rules of the changes progress, and it was the basement of the study on eco-environment evolvement. Based on the analysis of the land use styles number model, it was concluded that the land use style changes mainly incarnated in the phenomenon of"three increases and three decreases". Three increases meant the increase of the area of infield, woodland and saline-alkali soil. Three decreases meant the decrease of the area of grassland, water area and marsh. Thereinto the most increasing 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 the change of land-use fashion in different aspects and different rates. Interactional transforms take place in all kinds of land-use style. It is proved that the increasing of infield and saline-alkali soil costs the decreasing of grassland and marsh. The degradation of grassland and the increase of saline-alkali soil gave great effect to the degradation of eco-environment in the study area.During the evaluation of land ecosystem health, with the aid of the space analyses function of GIS, territory range of Tongyu county was divided by village evaluation units. From the viewpoint of systematic pressure, state and response, the index system was design according to AHP. With the model of fuzzy synthetical evaluated method, the evaluation of land ecosystem health in the west of Jilin province in 2004 was carried on through DPS software program. The result of evaluation was represented in the form of digital picture. The result indicated that the land ecosystem health in Tongyu county was in the unsafe state generally, but it was better in westen area. Status of land ecosystem health in Xiaili was worst, where the index was 0.3329. And status of land ecosystem health in Kaitong was best, where the index was 0.6158. 9 villages'healthy status was bad, and another 9 villages'healty status was worse. There was biggish pressure induced by human and nature all over the region, correlated with deteriorative land ecosystem and aridity climate. Because of desert and salina, the healthy status was better in middle and east area than in other area. Then, according to the result of land ecosystem health evaluation, the concrete guarantee measures of the land ecosystem health were proposed.