| At present, human being is affecting the global environment deeply at a wide extent and spatial scale, and land use has changed the earth's surface, which cuased changes in natural key elements and biological process; this effects are especially obvious in vulnerable areas. Therefore, the environmental effects of land use/ cover especially in vulnerable area have gotten more attention. The research on the interact of " human being driving force- land use/ cover change- the global change- environment feedback " becomes one of the important program in the International Humanity Factor Program (IHDP) and the International Geosphere Biosphere Program (IGBP). Up to now, the majority studies still put emphasis on the changes of the land use, while reseaches on the environmental effect of the land use caused by human activities appears insufficient.Environment vulnerability is the internal cause and important attribute of the environment. Ecological environment problems become intense in recent years, so the environment vulnerability catches more and more attention. The International Biology Plans (IBP), the Man and Biosphere Plan (MAB) and the International Geosphere Biosphere Program (IGBP) all take the environment vulnerability as the important field. The environment vulnerability is affected by the natural environmental conditions and the human being activities, and improper land use will be able to aggravate environment vulnerability degree. Chinese resource environment problem is especially severe, the contradiction of person and land is obvious, and china is one of the countries that have the maximum vulnerable area, maximum vulnerability types and the most obvious vulnerability. Therefore, the environment vulnerability study is especially important for preserving the environment and harmonizeing the relation between man and nature in China.Based on the main problems in the environment vulnerability study, this paper mainly discussed the environment vulnerability evaluation, spatio-temporal changes and the land use impacts on environment vulnerability.First, connotation and essence of the environment vulnerability have analyzed. We got the qualitative description and expression of the environment vulnerability based on theist forming mechanism. Environment vulnerability was analyzed from two levels of external comprise and internal environment. The emergence condition, essence and characteristics were ascertained. Owing to that, the environment vulnerability evolvement was analyzed.Secondly, the dynamic changes of environmental vulnerability at county level were assessed. Based on the requirements of environment management, focused on county level, this paper clarified the attributes of environmental vulnerability, selected evaluation indexes from three aspects of stability, sensitivity and applicability, and established the evaluation models, so as to systematically assess environmental vulnerability within county area. The results indicated that the environmental stability of Kenli County was instable, the environmental sensitivity appeared a descend trend and the environmental adaptability showed an uptrend as a whole during 1986-2003. The natural factor sensitivity analysis of Kenli County showed that their sensitivity sequence was that the groundwater level>evaporation and precipitation ratio>groundwater salinity>air temperature. Therefore, the natural sensitive factors of the study area were determined as the former three. The results of obstacle degree of regional adaptability indicated that the saline-alkali soil amelioration rate was the most important obstacle factor during 1986-2003, the restriction of the farmland shelter-forest density mainly appeared during 1995-1998, and the pesticide and fertilization application became the main obstacle since 2000, and the effective irrigation area ratio and the drainage system area ratio raised as the problem before 1990. The conclusions are that the environmental vulnerability of Kenli County is declining, but still in vulnerable state. At the same time, Kenli County should put the emphases on the development of the sensitive and obstacle factors. The assessment method can find the fundamental reasons and the development process of the county environmental vulnerability, which is significant for the current domestic study.Thirdly, this paper utilized the entropy theory and catastrophe theory to study the environmental vulnerability. Spatial-temporal variations of environmental vulnerability in Kenli County of the Yellow River Delta were systematically analyzed through environment samples and remote sensing techniques. Methods of analysis and estimation for the environmental vulnerability catastrophe were established. Our results indicated that the environment of the sample tended to deteriorating during the period of 1987 to 2005, and two catastrophes of environmental vulnerability occurred, one was in 1997, and the other in 2004. Their causes and characteristics were specified accordingly. In addition, spatial variations of environmental vulnerability along two direction lines of different distances to the Yellow River and to the ocean in Kenli County were analyzed, while the results testified the spatial gradual changing pattern of environmental vulnerability. Fourthly, based on the above analysis, this paper analyzed and assessed the impacts of land use on environmental vulnerability in Kenli County focusing on land use types.First, the remote sensing technique was adopted to acquire the land use information, and the vegetation conditions, soil water and surface evaporation were selected as the environmental vulnerability according to the actual situation in Kenli County and the RS image characteristic, which were also expressed by the RS indicators. The impacts of land use on vironmental vulnerability were analyzed through spatial lingking the environmental vulnerability factors and the land use. The vironmental vulnerability factors sequence of different land use type was got. The land use types were classified according to the disturb strength of human. The environmental vulnerability of different disturb degree was calculated by area weights.The quantitative study was divided into two parts, on one hand, the land use impacts to environmental vulnerability was calculated by ecologyical niche. The theoretical framework of land use's effect to vironmental vulnerability was established according to niche and suitability theories. Based on this, land ecological units were compartmentalized, and the requirement niche of land use was confirmed. Then the unit's vironmental vulnerability effects of land use were calculated, which were marked into four grades: not vulnerable, verge vulnerable, low-grade and high-grade vulnerable. On the other hand, focused on the land use types, the impacts of land use on environmental vulnerability was assessed, the assessment index system including landscape structure and pattern, land use ecological applicability and land use stability was established. Remote Sensing techniques were adopted to acquire land use information, expert decision method was used for index quantification, and AHP method was adopted for index weight determination. Based on these, the landscape structure and pattern index model, land use ecological applicability index model and land use stability index model were built up, and land use environment vulnerability effect index models were established accordingly. Through assessment, we got the land use environment vulnerability effect index values in two scales of the county and town. Land use impacts on environmental vulnerability and their spatial distribution were discovered. Based on the results, partition of land use adjustment in Kenli County was proposed, and countermeasures of ecological construction in different areas were brought forward.
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