| Minjiang upstream in Sichuan province and western regions is an important ecological barrier. Also it is the significant experimental subject of Natural Forest Protection Programme and the vital ecological barrier of the headwater of Yangtse River. For a long time, that the unreasonable resources development and utilization ways of human cause the contradiction among population, resources and environment increasingly. The contradiction limits the regional economic social development and gives rise to the week ecological environment which has endanger the ecological security of the Yangtse River basin. Based on this background, in this paper I choose arid valley of Minjiang River-Zagunao River as the subject, use space information technology(RS, GIS and RS), treat remote sensing data from 1980 to 2006 as the main data source and combine with terrain analysis to deeply analyse the subject of land use and landscape pattern in time series and space scale. Moreover, I dissect the quantity change of land use type, spatio:temporal evolution and space transfer law by using land use mapping model. Then by assessment of ecological environmental vulnerability in study area and exploration of ecological restoration approach in habitat vulnerability biota, in ecology protection and sustainable development of subject I expect to give the rationale and scientific advice which will effect an optimistic strategic influence in restoration and reconstruction of the ecological environment and sustainable development of river basin. The conclusions will be given in the following passages.(1) In the study area, proportion of landscape type, quantity of plaque and dominance distribute lopsidedly. Regional natural landscape (such as forest, grassland, shrub land and rocks exposed areas) account for the absolute dominant position, taking up over 90%. However, half natural landscape and anthropogenic landscape (such as cut over land, agricultural land and settlement place) occupy smaller proportion. It illustrates that in Zagunao River the dominated regional landscape pattern is natural scenery, and man-made landscape is obviously in ascendancy.(2) From 1980 to 2006, the transformation of land use pattern in Zagunao River area displayed in two ways. Firstly, the proportion of forest and unused land had reduced. The area of forest declined maximally, and that of unused land decreased minimally. Secondly, the acreage of shrub land, grass land, agricultural land and water area remained escalation. The increasing proportion of shrub land made up the biggest part of all,in the meanwhile, that of water area took up the smallest one.(3) Under the support of ArcGIS, I use 5* 5km grid as the statistical unit to get the spatial clustering of synthetic degree of land use by method of Natural Break. It could give us the space distribution pattern. From that, we can see the areas of high land use comprehensive level mainly locate in the place along Zagunao River. The main reasons why coast wise of Zagunao River display the high level of land use is the climate which is suit for living and the big degree of human interference. Also that the area which expresses the pattern status of reasonable use of various lands is very important.(4) The change of woodland barycenter coordinate is relatively complex. And it often changes from circumpolar latitude to low latitude, then back to circumpolar latitude. Grassland barycenter coordinate transforms low latitude into circumpolar latitude. Distribution frequency of high altitude gradient increases gradually. Shrubland barycenter coordinate turns low latitude into circumpolar latitude and high elevation curvilinearly. Unused land barycenter coordinate usually converts the areas of circumpolar latitude and low elevation into the places of low latitude and high elevation.(5) Valley area (from 1980 to 2006) had formed the regional landscape pattern which is forest-cultivated land-waters interlaced. In 2006, it had shaped the regional landscape pattern of stagger forest, shrub land and agricultural land. Half-high-mountain ares mainly formed sub-alpine acerola forest landscape pattern mixing with forest, shrub land and agricultural land. However, the main pattern in half-high-mountain and semi-mountain area was grassland-shrub land-forest interlaced sub-alpine bush meadow belt landscape pattern. This place was transitional zone from forest landscape to meadow landscape. High-mountain area primarily formed the high-mountain meadow landscape pattern with grassland, unused land and forest mixed.(6) Settlement place scatters in every slope partition, but mainly distributed in the flat slopes. The distribution of waters mainly concentrated in flat slope area. And the acreages of settlement place and waters arrived the peak in the area without slope. Both the forest and the shrub land stayed in the positive status in abrupt slope. Most forest was always in the area of partial adret slope and partial shady slope. And the distribution of shrub land was usually in the adret slope, not the shady slope. However, that of the grassland was in the opposite side. Also at the slope, the difference of distribution in grassland and shrub land is obvious.(7) The period from 1980 to 2006 witnessed a fact that the stable mapping unit occupied large proportion of units of every variation pattern map, making up 92.5245% in whole study area. And the variation pattern map, the area of which remained the top of the table, was'forest-forest-forest-forest'. The changing area of prophase type was 6758.28hm", ranked second with taking up 3.1005% of all. In this type, the variation pattern map which had the largest acreage was'forest-shrub land-shrub land-shrub land'. However, that in later period was'forest-forest-forest-shrub land'. The model with the biggest change of area in transitional type was'forest-forest-shrub land-shrub land'. In reiterative change model the variation pattern, the acreage of which is the biggest one, was'forest-shrub land-grassland-forest'. The sustainable change model was the mapping unit with the smallest area in whole. And in that type, the model with the largest change of acreage was' unused place-grassland-shrub land-forest'. Then the pattern status of sub-alpine shrub-meadow area with grassland-shrub land-forest interlaced had formed.(8) The study of grain-size effect chose several landscape indexes.And in these indexes, the grain-size effect was obviously found in plaques number, plaques boundary density, spread degrees,fractal dimension and landscape plaques gathered degrees which expressed the regular trend of variation.However, there was no granularity mutation effect in plaques boundary density, plaques shape index and landscape plaques gathered degrees. Landscape diversity index did not result in any obvious granularity mutation effect. So it can be said that landscape diversity index had low sensitivity of that.(9) Woodland landscape had the high gathered degree and the low separation degree, and the second was grassland. It expressed that in whole type of landscape, forest which constituted the dominant scenery had the highest degree of concentration distribution. And grassland had the higher degree of concentration distribution, constituting the main scenery. The gathered degree of waters landscape was the smallest of all, but the separation degree of that was the biggest. The settlement place had the smallest HFD in whole.(10) There were some facts. The gathered degree index turned to decline year by year. Spread degree index turned to increase, and average plaques area decreased. Regional landscape fragmentation degree intensified. And these result in the accumulation of landscape diversity and evenness and the decline of landscape dominance index. There was a negative correlation between landscape diversity and landscape dominance index. Also there was a positive correlation between landscape diversity and landscape evenness. It reflected that different landscape types made up the similar proportion. And the compositions of landscape types were uniformly distributed. The distribution of landscape types turned concentrated into scattered and crisscross. Most landscape patched distributed evenly. There was a decrease in landscape integrity and connectivity. Nevertheless, landscape heterogeneity increased.(11) The retention rate of grassland and unused places which were treated as the landscape types with large proportion of area in subject always stayed in the high level. Forest and shrub land had the higher switching-in rate and switching-out rate which varied most drastically. And the switching-in rate was more bigger the the switching-out rate. The result of high retention rate of waters was protected by the deep canyon in forest. The settlement place was effected by human beings easily. So its retention rate can remain stabilization or change sharply.(12) From the expected acreage, the area of settlement place always remain increase. The acreage of plowland and unused places turned to decline. That of the grassland, forest and waters decreased at first and then rose. However the area of shrub land stood in the opposite side. That expressed the gradual succession of plantation and secondary forest after the restoration of 18 years:the biomass live weight would increase, the ecological barrier function (such as water conservation, soil and water conservation, runoff regulation and biodiversity conservation) would recover stepwise, the quality of ecotope began to improve. Also that expressed ecological restoration of natural forest should experience a slow process.(13) To calculate the posibility of the ultimate state of the land use which is changed, and to converse the posibility to the area of the various land types, this paper will combine the posibility of the ultimate state with the CA-Markov firstly, and creatively simulate and predict the land use of studied area, its final result shows that:the area of plow land, shrub land and used places turned to decrease. That of shrub land and used places dropt sharply than that of plow land. The area of grass land and forest had the trend of increase. And the rise of the area of forest was more rapid. The area of waters remain stabilization nearly.(14) The dominant vegetation types in deep erosion region ware plow land and grassland. However, that in moderate erosion area mainly distributed in shrub land. The dominant vegetation type in mild erosion and micro degree erosion area was the broad leaved deciduous forest and the leaved and coniferous mixed forest. And the micro degree erosion area mainly distributed in the shrub land. The dominant vegetation type in both no erosion region and micro degree erosion region was coniferous forest. All in all, from the level of ability to control soil erosion intensity:coniferous forest>broad leaved deciduous forest>leaved and coniferous mixed forest>shrub land>grassland>agricultural land.(15) The assessment of ecological vulnerability of the Zagunao river can be divided into five levels, as follows:EVI belows 25 as the slight vulnerability, the proportion of the area is 2.7040%;EVI between 26-40 as the light vulnerability, the proportion of the area is 36.0134%;EVI between 41-55 as the medium vulnerability, the proportion of the area is 29.8752%;EVI between 56-70 as the high vulnerability, the proportion of the area is 19.5512%;EVI higher than 70 as the extreme vulnerability, the proportion of the area is 11.8562%. Thesum of the proportion of the area of slightly vulnerable and light vulnerable is only 38.7174. It indicates that the overall operation state of the ecological system is general, and there are the high and extreme areas about 31.4074%. It shows that the environmental problems are still severe. The dry climate, the Poor soil, the drought and the water shortage and the fregeuntly geological disaster are the natrual basis of the formation of the ecological vulnerability. Human origin of the severe ecological vulnerability. More and more human activities,especially unreasonable herd and abundant assart is the essentially.(16) There is no independent validation for the existing assessment of ecological vulnerability which is almost one-way. Based on the literature review, this paper creatively puts forward the method to verify the results of the ecological vulnerability assessment. Then analyze the relationship of the rate of the average coverage and the value of the environmental vulnerability evaluation which are extracted by the center point of the grid. The result of it shows that the vegetation index decides almost 3/4 of the ecologically vulnerable zone. In a sense, the density of ragional vegetation can largly decise the extent of the ecological vulnerability in a region. The research of the relation between the rate of vegetation covering and the level of ecological vulnerability enables us verify the result of the assessment of ecological vulnerability according to vegetation index. Moreover, the research dedicates that assessment result can well reflect the actual situation of the regionally ecological vulnerability which is studied.(17) From the 3D trend surface model analysis of habitat fragile degree in different elevation and aspect, the area with low habitat fragile degree mainly distributed in the half-high-mountain and semi-mountain area, especially in the area with the elevation between 3400m to 3800m. The secondary is valley area. In this area, habitat fragile degree had the negative correlation with elevation. In sub-alpine area and alpine area, with the increase of elevation, the habitat fragile degree turned to become more higher. With the change of aspect, the habitat fragile degree in different elevation did not have any obvious transformation, whereas it expressed a trend of low increase in whole.(18) In gradient, habitat fragile degree expressed'∪'curve. Nevertheless, it expressed the trend of slow increase in aspect. The area with low habitat fragile degree mainly distribute in the cross area between 21-420 gradient and 60-1600 aspect. If gradient between 42-900, habitat fragile degree was proportional to the aspect. If gradient between 600-900, when aspect rose, EVI expressed'∪'curve. In the sunny slope and the semi-sunny slope, habitat fragile degree was more lower. However, that in the other site conditions was more higher.(19) In elevation, habitat fragile degree expressed'∪'curve. However, in gradient it expressed decline arc curve with large radian. The area with poor habitat fragile degree mainly distributed in the half-high-mountain and semi-mountain area with gradient between21-420.
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