Gansu Loess Hilly And Gully Region Of Ecosystem Health Assessment

With the development of the modern science technology and the global economic growth, the human being are influenceing the environment, changeing and destroying the natural ecosystem at an unprecedented scale and intensity. As a result, the ecosystem health is dameged more and more, the humankind is also endangered and now it is putting a common attention to the environment. The ecological health and the ecological security become the hot topics of the scholars studies. In the history , the Longzhong loess hill gully area was covered with luxuriant forest and had a beautiful scenery . However ,with the humanitys excessive reclamation and extensive cultivation ,the vegetation was destroyed and aggrevated, So that the area has become the world's most serious soil erosion areas.And it is also one of the frailest ecological areas in our country . So in this article ,it did a synthetic research on the condition of the ecosystem health from the great system of the Longzhong loess hill gully area and then explorated and practiceed the research theory and method about the ecology health. This has not only the vital scientific significance, but also the very important applied value by which the government could grasp the changes of the ecosystem health about the Loess Highlands hill gully area and take measures on time according to it.In this article ,it taked the research of Yuzhong area for example , combined the ecosystem's structure and function together on the basis of ecosystem health and formated the topic raster layers of each evaluation factors based on the remote sensing images, the DEM , the field survey datas and the 3S techonology . In the view of the natural and human elements that effected the ecosystem health,used the AHP ,and choosed six evalution factors of the ecosystem health—vigor , organizational structure , capacity , resilience, the ecosystems maintenance functions ,and the external input and human health as evaluation based on the principles in choosing evaluation factors . The article constructed the ecosyetem health status system , evaluated the condition of ecosyetem health and explored the region's ecosystem health differences in time and space.This article drawed the following conclusions and important results through in in-depth scientific and comprehensive study.1) the changeable characteristics of the principal ecosystem health evaluation①Land-use changeCultivated land was a major general in YuZhong,that was followed by the grass land,the least type of land : garden plot in 1991, water land in 2002 and in 2006 .②The organic production of ecosystem . The total of the organic production of ecosystem was 1659476.45 tons in 1991, 1479552.75tons in 2002, tons 1497894.53 in 2006.③Natural ecosystem servicesSoil conservation of vegetation ecosystem was 2112431.82 tons in 1991, 2014629.39 tons in 2002, 2081419.39 tons in 2006. Vegetation conserving water was 6990337.007 tons in 1991, 7334867.2 tons in 2002,7344755.83 tons in 2006. Absorption of carbon dioxide of ecosyetem was is 2704946.6 tons in 1991, 2411671 tons in 2002, 2441568 tons in 2006. Releasing oxygen of ecosyetem was 1991371.74 tons in 1991,1775463.3 tons in 2002, 1797437.4 tons in 2006. 2) Ecosystem healthThe average index of ecosystem health is 0.4725,the lowest index of region ecosystem health is 0.2912,the highest index is 0.7119 in 1991 .The average index of ecosystem health is 0.44304, the lowest index of region ecosystem health is 0.2655, the highest index is 0.7115 in 2002. The average index of ecosystem health is 0.443889, the lowest index of region ecosystem health is 0.2733, the highest index is 0.7116. From 1991 to 2006 ,the situation of ecosystem health in Yuzhong was in the moderate health level. There is an significantly decling ecosystem health in 2002 than in 1991, an significantly increase in 2006 than in 2002.The regional of ecosystem which are over health standards (>0.6) distributed in Xinglong mountain and Maxian mountain. The regional of ecosystem which are moderately health(0.4-0.6) are the most extensive,there were Yinshan ,Shangzhuang, north of Mapo and the most area of Xinying,jinya,Laizibao,Xiaguanying of Central ward region ,lujiagou,Yuanzicha,Qincheng of the northern mountains region. Ecosystem health for the general disease (0.2-0.4) of the region mainly distributed in Gaoya,Sanjiaocheng,Qingshui,Gancaodian of Central Ward region,Shanghuacha,Gong -jing,Kaiping of the northern mountains region. Most of the regional ecosystem health condition has declined, the rural ecological health of individual performance increased slightly, from the whole entire study area, the ecosystem health showed declining trend, from 1991 to 2006, in Yuzhong.There are some progression and innovation in the article as follows:1) The article builds the ecosystem health assessment index system about the loess hill gully area, according to the Loess Plateau area of objective conditions and taking into account the human stress on the ecosystem health effects from natural and human factors point of view.2) The article extracts the evaluation of ecosystem health indicators factor in the Loess Plateau District by 3S ,which could reflect ecological health more accurately.3)In the evaluation methods aspect,it ameliorats the evaluation model of the ecosystem health objecti -vely, learning from the predecessors in the research results. It also overcoms a single factor evaluati -on services limitations by using the value of the ecosystem service function to reflect the service function of ecosystem health evaluation.4) Using the topical raster layers of evaluation factors, the article accomplishs the evalution of ecosystem health on the support of the GIS and RS which have powerful functions in layer staking and mode arithmetic.