| Land, as one of the most important resources for human survival and development, is the carrier of human existence and the place where all human activities of production and living take place. For good man-land relationship and sustainable use of land resources are the basis for economic and social sustainable development, it is of great significance that the relationship between man and land should be well coordinated and use of land should be sustainable. Evaluation for sustainable land use is the key problem and an inevitable part in the research of the sustainable land use from theory to practice, it works as an important means of implementing sustainable land use, and it is an important basis for the renovation of regional land, the planning for land use and the formulation of the land use system. "Structure decides function", the stability of the spatial mosaic of land is the foundation of the stability of land function, and it is also the premise of sustainable land use. On the evaluation contents of sustainable land use, the researches in this area currently mainly emphasis on the multi-temporal changes of land functions, but the spatial pattern of land use draws less attention in the study field. On the evaluation merhods of sustainable land use, the current researches mainly take the linear weighting method, but some new evaluation methods, such as neural network method, projection pursuit comprehensive evaluation method and so on, have not been well applied so far.Enshi Tujia and Miao Autonomous Prefecture is the only region in the Great Western Development in Hubei Province, it is an important part of the Western Hubei Eco-cultural Tourism Circle. With the Yichang-Wanzhou railway opened and the western section of Shanghai-Chengdu Expressway opened, the advance of Great Western Development and the construction of Western Hubei Eco-cultural Tourism Circle will certainly give a boost to the social economy of this area and brings unprecedented pressure to the regional land use at the same time. Currently, the region keeps a good ecological environment, but belongs to typically ecological fragile areas, thus, the ecological environment, once damaged, will be difficult to restore. Therefore, it is of great significance to achieve regional sustainable development to develop evaluation for sustainable land use in this area, identify the current situation of land use, find out the limiting factors of sustainable land use, and put forward countermeasures to realize regional sustainable land use.This paper first discusses theoretically about the relationship between the changes of spatial patterns of landscape and evaluation for sustainable land use.The regional people's behavior of land-use forms a particular landscape spatial pattern; landscape spatial pattern is the result of land use. Firstly, from the perspective of spatial entity, landscape and land have great similarities. Human economic activities are mainly carried out at the landscape level, the landscape provides a variety of resources and sites for human economic activities and it is the objection for human beings to use and develop. Whereas, land is a fundamental means of production for human beings, and it provides venues and space for human production and life. All human life and production must be implemented in land reflected as spatial and temporal changes in human behavior and way of land-use. Therefore, the landscape is the result of land use. There exist great similarities between landscape types and land-use types, landscape structure and land-use structure, landscape function and land function, landscape changes and land use/cover changes. Secondly, the perspective of evolution of spatial pattern, at short time-scale, human behavior of land use is the main driving factor for the evolution of spatial pattern.Land is a synthesis of physical geography, a composition of different land use types in the space mosaic and is of obvious spatial heterogeneity. It is generally believed that the heterogeneity is enhanced in a certain range can help to improve the stability of landscape, while the stability of space mosaic is the base for the stability of function. According to the theories of ecological integrity and spatial heterogeneity, the essence of regional sustainable land use is to construct a reasonable spatial heterogeneity and to maintain the ecological integrity of land use. Evaluation for sustainable land use should not be limited to analyze the constituent elements, but to grasp the features of the system as a whole and to have a comprehensive consideration of social, economic and ecological factors to evaluate. On regional land use, sustainable land use is the continuation and maintenance of land function, which requires seeking the stability of the land function, while the stability of land function is based on the stability of landscape spatial mosaic. Therefore, evaluation for sustainable land use is not only mainly on the land function, but also on the landscape spatial pattern (spatial structure of land use), especially on the stability of the landscape spatial pattern. In the aspect of quantitative evaluation for the stability of landscape spatial pattern, for the spatial heterogeneity is the basis for the stability of spatial pattern, relevant indicators of spatial heterogeneity are generally used to evaluate the stability of landscape pattern.On this basis, this paper puts forward the evaluation for sustainable land use based on landscape spatial patterns as follows: Sustainable land use means that the regional land can bring about steady, sustainable and high comprehensive benefits in face of certain pressure to meet the needs of the human socio-economic system, whereas the stability of the land function is based on the stability of land spatial mosaic. Therefore, evaluation for sustainable land use based on landscape spatial patterns is the integrated evaluation of the pressure, landscape spatial structure and the comprehensive benefits. Pressure is the driving factor for the change of the sustainability of land use, the optimal comprehensive benefits are the ultimate goal of sustainable land use, and the stability of landscape spatial mosaic is the basis for achieving sustainable land use. To carry out the evaluation for sustainable land use based on landscape spatial patterns can not only achieve the combination of structure and function but also the coupling of time and space.Based on the research of the relationship between landscape spatial patterns and evaluation for sustainable land use, this paper comprehensively uses "3S" technologies and Landscape ecology approach based on data sources of ETM+and TM remote sensing images, SRTM DEM remote sensing data to study the change of land and the evolution of spatial pattern since 1990, and carry out quantitative assessments of the ecological environmental impact (Including net primary biological productivity, the value of ecosystem services, ecological footprint, and benefits of soil and water conservation). On this basis, the paper establishes an index system of evaluation for sustainable land use, applying the "3S" technologies sustainable use based on landscape spatial patterns of "pressure-function-structure" of study area, and gives assessments for the sustainability of land use in this region since 1990 and undertakes a comprehensive diagnosis of obstacle factors to put forward specific countermeasures for the sustainable use of land.The research shows that:1.Landscape ecological principles bring about new.requirements for the method, criteria and approach in the evaluation for sustainable land use. On the method of evaluation for sustainable land use, it is to take into comprehensive consideration of social factors, the economic factors and ecological factors on land use, and to put land use systems on the context of regional sustainable development and grasp the characteristics of overall system to do evaluations by taking into consideration of various factors. On the criteria of sustainable land use, it is to pursue an integrated optimization in the ecological, economic, social and aesthetic benefits rather than economic benefit maximization of a single cost-effective. On the approach to the technical evaluation, the essence of regional sustainable land use is the continuing construction of spatial heterogeneity and the dynamic maintain of ecological integrity. In Sustainable land use, it is required to keep the stability of the landscape, evaluation for sustainable land use is to evaluate not only the function of land but also the landscape spatial pattern (spatial structure of land use). The growth of human population and the economic and social development will promote human beings to strengthen land use, change their behavior of land use in space and way so as to derive sufficient output to sustain the population survival and the development of social economy, leading to the evolution of landscape patterns. Therefore, evaluation for sustainable land use based on landscape spatial patterns is actually the comprehensive evaluation of the pressure on regional land, landscape spatial structure and overall comprehensive benefit. Pressure is the driving factor of sustainability of land use changes driving comprehensive benefits, the optimal is the ultimate goal of sustainable land use, the stability of the spatial mosaic of landscape is the basis for achieving sustainable land use. Based on landscape spatial pattern, evaluation for sustainable land use can realize not only the combination of the structure and function but also the coupling of time and space.2.Since 1990, great changes have taken place more rapidly in the use of regional land, the major change is the sharp decline in grassland and cultivated land. With the continuing growth of wood land, the aggregation of spatial pattern has continued to improve, and the diversity to decline, thus the stability of spatial patterns has a consistent decline.From the perspective of changes in number during 1990～2000, the magnitude of changes in descending order were as follows:woodland (7.92%)> grassland (-6.20%)> arable land (-2.19%)> waters (0.23%> construction land (0.23%).The proportion of changes in waters and construction land are the same, but the area of waters has a bigger change. From 2000 to 2007, the magnitude of changes were as follows:arable land (-8.41%)>woodland (8.17%)> grassland (-0.14%)> construction land (0.11%)> waters(0.06%).From the perspective of the intensity of land-use changes to compare the two study periods, the intensity of land changes in the period from the year of 2000 to 2007 is more severe. From 1990 to 2000, the dynamic intensity for the regional comprehensive land-use is 6.06%, and the intensity of land-use changes by descending order is as follows:waters (11.51%)> grassland (-9.42%)> construction land (2.11%)> woodland (1.51%)> arable land (-0.55%).From 2000 to 2007, the dynamic intensity for the regional comprehensive land-use is 9.83%, the intensity of land-use changes by descending order is as follows:grassland (-5.23%)>arable land (-3.19%)> waters (1.95%)>woodland (1.94%)>construction land (1.09%).From the perspective of spatial distribution of land-use types, since 1990, the basic trend to the spatial distribution of land-use types is:the grassland continues to shrink to the mountains, woodland continues to spread to the low- altitude areas and the arable land further continues to back upon the low- altitude gully land. From 1990 to 2000, the average elevation of arable land distribution fell 25.92 meters with an average slope of 1.24 degrees decreased, the average elevation of grassland distribution increased 474.73 meters with an average slope of 1 degrees increased. From 2000 to 2007, the average elevation of woodland distribution fell 5.23 meters with an average slope of 0.98 degrees decreased, the average elevation of arable land distribution fell 96.99meters with an average slope of 0.97 degrees decreased, and grassland continues to shrink to the high mountains, with an average elevation in the distribution of 124.73 meters increased.From the perspective of spatial pattern of regional land use, since 1990, the aggregation degree of spatial pattern continues to increase with the diversity index continuously declining and the stability of spatial pattern diminishing. From 1990 to 2000, the patch number of the regional land use increased from the number of 244128 to 383276, and the average patch area decreased from 9.91 hectares to 6.31 hectares. Mean shape index, Fractal dimension and fractal indicators are big, and the land-use spatial patterns becomes more complicated and fragmentation. The richness and evenness change respectively from 0.7561 and 0.5302 in 1990 to 0.8522 and 0.4705 in 2000, which indicates that the dominant role of the two land-use types of woodland and arable land that affected regional land use pattern is enhanced. The aggregation degree of landscape is further improved, the dominant role of the two land-use types of woodland and arable land is further enhanced and the diversity index of the spatial pattern is further reduced.3.Due to the growth of population and the restructuring of land use, the ecological carrying capacity of land has been decreased, but generally the eco- environment benefits of the regional land use continues to be improved.From the perspective of Area-weighted average NPP, the net primary productivity in the study area continued to increase,in 1990, the regional average NPP was 15.78t/(hm2·a), in 2000, the regional average NPP rose to 15.86t/(hm2·a), and in 2007, the regional average NPP rose to 16.63 t/(hm2·a). The land types of NPP sorted by the size are:woodland> arable land> grassland> construction land> waters. From the NPP Maximum in per unit area, the NPP Maximum in 1990 was 83.43 t/(hm2·a), the average NPP Maximum in 2000 and 2007 are 98.87 t/(hm2·a),thus the improvement of the ecological environment during the study period leads to not only the continuous growth of the forest coverage rate, but also brings better growth situation to the forest and makes biological production functioning better.The results of the value evaluation for ecosystem services show that:since the year of 1990, the value of ecosystem services in the study area keeps growing, which shows that the quality of the ecological environment in this region is continuously improved and the function of the ecosystem services is improved. From the perspective of the land-use types, woodland and arable land are the region's main parts in forming the value for the regional ecosystem services, the value of wood land eco-system services takes up the maximum and is to be strengthened over time.From the perspective of ecological footprint, since the year of 1990, the regional per capita ecological footprint continues to grow, while the per capita ecological capacity continues to decline, the study area had slight ecological surplus in 1990, and then it had ecological deficit. In 1990, the per capita ecological footprint was 1.23hm2, in 2000, it was 1.44 hm2, and it rose to2.2 hm2 in 2007. Compared the two periods, the rise in per capita ecological footprint is faster after 2000. Among them, ecological footprint of energy consumption takes up a large proportion in the whole ecological footprint and it grows rapidly. The per capita ecological capacity continues to decline, in 1990, the per capita ecological capacity is 1.447 hm2, and it dropped to 1.3846 hm2 in 2000, and it continuously reduced to 1.2203 hm2 in 2007.The evaluation results of the soil erosion in this region show:due to the high coverage of forests in the study area, the soil erosion is slight, and the conservation benefits of soil and water are good. The maximum modulus of soil erosion was 694.947 t/km2-a in 1990, it was 693.507 t/km2-a in 2000, and was 670.764 t/km2-a in 2007. According to the criteria of soil erosion classification and grading, the overall situation of soil erosion in the study area was slight-erosion since 1990. The area of soil loss was 558.9 hectares in 1990,243.81 hectares in 2000 and 230.04 hectares in 2007. Taking the largest area of soil loss in 1990 for consideration, the area of soil loss takes up only 2/10000 in the proportion of the total land area in the study area.4. The sustainability of regional land use in the study area has continuously been declining since 1990. The major obstacle factors of sustainable land use in 1990 were the low level of grain production and the relatively poor regional eco-environment. After 1990, with the adoption of Forest Conservation Measures and the Policy of Converting arable land to Forestry in the region, the ecological environment continues to be improved. The major limiting factors of sustainable land use are the growth of construction land, the increasing of population composite consumption level and the declining of landscape diversity.Finally, this paper puts forward the countermeasures for regional sustainable land use:first, to strengthen the construction of basic farmland, protect arable land, implement land management and improve the output capacity of arable land; second, to use construction land economically and intensively and control the occupation of construction land on arable land; third, to seize the opportunity to carry out industrial restructuring and apply the Principle of decentralization of Landscape Ecology to constructing ecological security pattern; and at last, to establish regional ecological compensation mechanism and adhere to the continuity of the Policy of Converting arable land to. Forestry.
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