| Land use change, one of the primary causes of global environmental change, has caused many concerns of global change researches. Since the project of land use/cover change (LUCC) was put forward by international global biological project (IGBP) and international human diathesis project (IHDP) in 1995 the project has stepped into the phase of systematic research, and has achieved great deal. However, with the insight into this field, scientists have increasingly realized that the study on land use change at the regional or local level is a key to understand deeply the past, current and future situation of the research in the earth system, and the study on the region or local land use change has become a new hot spot. Local level is treated as a primary place responding to the changes of regional and global level. The disturbance of human land use at local level affects not only the dynamic of population of regional terrestrial ecosystem, but also the content of greenhouse gasses in atmosphere. Thus, the activities in human land use has not been ecumenical factor other key factor in disturbing terrestrial ecosystem at the local level. Now some researches in regional LUC are being carried out mainly in the areas of the tropical rain forest, the loess plateau, the karsts and in the economically developed areas; but the researches bearing the global and regional features in the intensive farming areas, Zhujiang Delta and in such economically-developed areas as Suzhou, Wuxi and Changshu are not enough; practically the researches in western ecologically fragile areas in China are much less. Chongqing, as the center of western economic construction and development, its industrialization and urbanization speeds the frequency and extent of transformation between agricultural land and construction land, spur the flow of labor among the different industries as well, especially the flow of labors from rural areas to the secondary industry and tertiary industry. The changes of the patterns and management of land use will accelerate the transformation among land use categories too. Taking Shapingba district in Chongqing as a study area, combining the current data of land use with the socio-economic materials, adopting GIS, landscape pattern metrics, conversion-out and conversion-in contribution rate, ecological service value and land economic coefficient and analyzing its characteristics of land use change, landscape patterns as well as the process of ecological response, this paper predicts the future changes of ecological service functions in Shapingba district. The results indicate as follows:(1) The shallow hilly geomorphology zone was the dominant active area disturbed in human land use. The geomorphology type in Shapingba district consists of shallow hill, meso-hill and hill, herein shallow hill was in absolute dominance with the proportion of 56.63 % of study area. The cultivated land with about proportion of 97.00% of shallow hill zone and with about 44.59% of study area was the substratum in which other landscapes were inlaid. Because the cultivated land was disturbed and influenced dramatically, the fragmentation of landscape was high, and stability and resilience of ecology were worse. So the shallow hill zone will be the sensitive place where land use categories transformed and ecological environment changed. In meso-hill geomorphology zone, there were few land use types and inconspicuous substratum of landscape class. Patches of diversified landscape class were inlaid one another. Meanwhile patches possessed lower geometrical similarity, irregular characteristics of shape, zigzag borderline, and lower core area. Owe to interactional function among various landscape classes, exchanges among substance, energy and information were complicated. In the hill geomorphology zone, woodland with 51.47 % was the main land use type. Its patches had complicated shape of geometry, irregular characteristics of shape, zigzag borderline, and lower geometrical similarity. Because of lower disturbance of human land use for landscape, it is transiting to proto-ecosystem gradually. Corridor plays an important part in the ecological flow in landscape ecological system. It not only influences the distribution of land use types, but also worsens landscape and results in fragmentation of landscape. In the study area, the distribution of corridor consisted of water system, road and county road. According to the results of corridor index calculated, the relationship among the geomorphology types was shallow hill zone (22.5423)> meso-hill zone (19.3281) > hill zone (8.2354). The fragmentation of shallow hill zone was the highest, the meso-hill zone higher, and the hill zone the lowest.(2) Cultivated land landscape was the primary disturbance landscape type disturbed by human land use in Shapingba district, Chongqing. The disturbance of human land use was affected obviously by gradient. Various landscape elements were distributed and disturbed differently in the gradient of 0°-2°, 2°-6°, 6°-150,15°-250, and >25°. Cultivated land distributed mainly in the gradient of 0°-2°and 2°-6°consisted of landscape elements of winter water-stored paddy field and dry land. Due to other landscape elements inlaid in it, cultivated land landscape had high heterogeneity. Moreover, winter water-stored paddy field was close to substratum of paddy land landscape. Its patches possessed regular characteristics of shape and high discrete degree. By Buffer analysis of 50 m, 100 m, 250 m and 500m of Liangtan River, the distribution of patches of winter water-stored paddy field landscape element closely related to distance of Buffer zone of river. The number of patches and area of element rise along with the increase of distance of Buffer zone, and the patches of winter water-stored paddy field landscape element distributed mostly in the Buffer zone of 500m. As a whole, the patches of dry land landscape element scattered irregularly in dry land landscape class. The distribution of the patches of upland field was asymmetry and its borderline was relatively smooth. It is obvious that the gradient is a crucially restrictive factor, which human activities of land use disturb cultivated land landscape class. The region of human's disturbance lay mostly in 2°-6°gradient. But it was disturbed mildly under 15°-25°and >25°gradient. Subsequently, the cultivated land with 2°-6°gradient will be a key to carry out land sustainable use, and with 15°-25°and >25°slope degrees to improve ecological environment in the study area. The patches of winter water-stored paddy field landscape element lay mainly in slop gradient of 2°-6°and disturbed intensively by human land use. The patches of irrigable paddy field distributed also in the same slop gradient and were disturbed intensively by human land use. However, the patches distributing in the gradient of 0°-2°were even. The patches of rain-fed winter water-stored paddy field distributed evenly in the five gradients of 0°-2°, 2°-6°, 6°-15°, 15°-25°, and >25°. Their patches possessed the features of complicated shapes, smooth borderline, and low human disturbance. Though the patches of upland field distributed in the five gradients of 0°-2°, 2°-6°, 6°-15°, 15°-25°, and >25°, they concentrated in the three gradients of 6°-15°, 2°-6°and 15°-25°. As a whole, they had the features of complicated shape, smooth borderline, lower disturbance for human land use and lower land use. But the patches of fruit-tree inter-planting dry land distributed in the gradient of 15°-25°and >25°, and possessed low core areas. Due to lower human disturbance, fruit-tree inter-planting dryland will be gradually transiting to fruit-tree inter-planting garden plot correspondingly.(3) Land use pattern influenced differently purple soil fertility. Its land economic coefficient responded to purple soil fertility obviously, i.e., high abilities of soil conservation fertility and soil fertility supply will have high land economic coefficient. Rational land use pattern does not result in quality degeneration of soil fertility and cultivated land. The results were as follow: food crop intercropping economic crop relay cropping vegetable (FEV)> vegetable intercropping economic crop relay cropping vegetable (VEV) > fruitage intercropping food crop relay cropping vegetable (FFV) > food crop intercropping legume relay cropping food crop (FLF) > Mono-cropping (MONO). The changes of extent of soil organic matters were FEV > VEV > FFV > FLF. The amplitude-change of soil total N was the highest up to 55.55 % under VEV, alkaline hydrolysis N up to 124.02 % under FEV, and quick result P up to 140.74% under FFV. However, the extent of soil K changed consistently base on five land use patterns, and amplitude-change was between 20 % and 35 %. The extent of soil effectual Zn was close to critical value (≤1.00 mg.kg-1) of Zn-lacking under FLF, FEV, VEV, and FFV. But extent of effectual B, effectual Cu and effectual Mo was all low critical value (<2.00 mg.kg-1) of Cu-lacking, critical value (< 0.25 mg.kg-1) of B-lacking, critical value (< 0.15 mg.kg-1) of Mo-lacking. By calculating land economic coefficient of different land use pattern, the result was VEV> FFV> FFV> FEV> FLF> MONO. VEV had the best soil characteristic, its land economic coefficient was 0.791, inferior to none correspondingly. However, MONO was 0.429, the lowest one. In the study area, VEV is optimum land use pattern. In a word, land economic benefit of VEV is the highest under the same matter-devotion, or matter-devotion of VEV is the lowest under the certainty yield.(4) In Shapingba district, Chongqing, urbanization, industrialization and labor transformation were important driving forces for inducing land use change in study area. The ecological response process to land use change laid mainly in the increase of city landscape and ecological land, and weakening of the disturbance of land use for slope-cultivated land. Due to the decrease of paddy land and dry land landscape and the increase of artificial landscape of city landscape and so on, ecological function of artificial landscape will be strengthened. During 1996-2006, construction land rose from 6574.53 hm2 to 11891.08 hm2, 1.81 times of the past. The conversion-in areas possessing about 95% was subject to the cultivated land. The trend transforming from agricultural land to construction land will continue in Shapingba district, Chongqing. Moreover, the competition of a contradiction will be impetuous increasingly. How to balance the contradiction, control urban sprawl and protect cultivated land will be a keystone of future land use in the study area. More and more rural labors are transforming from first industry to second and third industry, labors of concurrent-agro-industry, non-concurrent-agro-industry and non-agro-industry increased, which led to the following results: the proportion of employment of rural non-agricultural population increased; the farmers' independence on land weakened; rural market became the orientation of choosing land use patterns; the transformation of inter-agricultural land and the choices of land use patterns were speeded. The regulation of agricultural structure in study area is one of primary driving forces. The transformation between agricultural and constructional lands speeded the increase and accumulation of such artificial landscapes as city. The process of eco-response will cause negative influence on the eco-environment in the Shapingba district. The process of eco-response, the increasing of such eco-lands as woodland and garden land and the weakening of the disturbance of activities of human land use, benefited improving the eco-environment in study area.(5) The total ecological service value was descent, the differentiation of its spatial distribution was obvious, and the contribution of the towns to it was various. Ecological service value coefficient assigning different categories of land use raised by Costanza was generally adopted at the global level. If we adopted it at the local level, ecological service value coefficient assigning different categories of land use had little influence on the total ecological service value, and the total change of ecological service value was inelastic in the region, but ecological service value coefficient assigning every category was different. By sensitivity analysis, this paper determined the dependence of our estimates of changes in ecosystem service values on the applied coefficients. The ecosystem vale coefficients for cropland, temperate/boreal forest, and laker/rivers were each adjusted by 50 %. The relatively low Coefficients of Sensitivity values reflected the fact that the coefficient values for cultivated land (92 $·hm-2·yr-1), garden land(302 $·hm-2·yr-1), for woodland(302 $·hm-2·yr-1) were close to regional actualities. However, the coefficient values for water land, compared to the coefficient of the laker/river (8498 $·hm-2·yr-1) assigned by Costanza et al. was more than the actual one. By rectifying 30 percent of the previous coefficient by 5667 $·hm-2·yr-1, it will be very close to the actual one. During 1996-2006, the ecological service value reduced from $ 1.50 million to $ 1.40 million, the net loss reached $ 0.10 million in the region. Accordingly, each hectare land suffered an average loss of $ 25.54 in the Shapingba district, Chongqing. There were eleven towns whose ecological service value hardly changed from 1996 to 2006 in Shapingba district, Chongqing, in which the value of six towns descended, i.e. Huxi town, Chenjiaqiao town, Qijiagan town, Zengjia town, Qingmuguan town, and Fenghuang town, and the other five towns rose, i.e. Jingkou town, Huilongba town, Zhongliang town, Xiyong town, and Tuzhu town. This paper found that six towns' ecological service value changed between by 20 % and by 40 %. In Tuzhu town, the increase of ecological service value was the highest during 1996-2006, i.e. 36.18 %, but in Huxi town the decrease of ecological service vale was the most considerable, i.e. 62.68 %. However, in both Jingkou town and Huilongba town, the changes of ecological service vale were less obvious, just -0.03 % and 4.00 % respectively. According to its spatial distribution of ecological service value in 2006, the contribution rate of Geleshan town and Zhongliang town was higher, i.e. 10.00 % and 11.27 % respectively, but Huxi town the lowest, i.e. 1.91 %. According to the spatial distribution of ecological service value and its changes, combining the influence of different land use patterns on the fertility of purple soil and the analysis of driving force leading to land use changes, this paper predicted that the future natural eco-system had four trends as follows: (1) the stable zone of eco-system, mainly in Jingkou town and Huilongba town; (2) descend-to-rise zone, mainly in Qinjiagang town and Huxi town; (3) eco-system sensitive zone, mainly in Chenjiaqiao town, Zengjia town and Tuzhu town; (4) sustainably-increased zone, mainly in Geleshan town and Zhongliang town.To sum up, the study provides a new perspective for the research of land use change and eco-benefit: soil—land use category—disturbance zone of primary human land use activities—configuration at the local level. This perspective offers theoretical framework in differentiating land use pattern based on eco-system sustainable land use at the local level. In the meantime, the integration of economic, ecological and social benefits is the final goal of land use. The eco-system benefit from the quantification of land use provides not only theoretical basis for constituting the total land use planning and optimizing land use structure, but also practical reference for constituting land policy and normalizing land use behavior to realize the suitability of land use. Meanwhile, the eco-response caused by land use change is multi-dimension, and this process plays a decisive role in the course and attributes of influencing environments and the dynamic of land use. The hydrological effect, the dynamic change of species, the transformation among biomass of land use category and the profits-and-losses balance of natural and artificial eco-system caused by long-term location, quantification study of land use change is a new solution to realizing the stability and sustainability of eco-system at the local level. |
PDF Full Text Request