| Human activities profoundly affect the pattern of land use and its change at present.Therefore,it's great significant to explore the causes and mechanism of land use change and simulate the distribution of future land use pattern for the current land policy and land planning.Based on interpretation data of Landsat images in 1995,2005 and 2015,this article realizes the spatio-temporal patterns of land use simulation by integrating GIS spatial analysis technique,CA-Markov model and MCE model,taking the lower reaches of Wujiang river as the study area,such as Fuling district and so on.With the method of scenario analysis,the land use pattern of 2020,2035 and 2050 in the study area are discussed under three scenerios containing ‘rapid urbanization scenario',‘Planning scenario' and ‘ecological protection scenario'.Based on the actual value of ecological service value,the value of ecological service value is estimated by using the net primary productivity,precipitation and soil data of the study area,and then the value of ecosystem service value estimation method is used to estimate the value of ecosystem services in the study area.Calculating the value of ecosystem services in different scenarios in the future.The results show that:(1)The study area is mainly farmland and woodland,and both accounted for 86% of the total area and more than 20 years,has experienced the process of cultivated land "first decreased and then increased," 10 years ago by 451.85km2,accounting for the total area of cultivated land(1995)of the 6.84%,after 10 years of cultivated land area increased slightly,but the increase over the slow;on the contrary,woodland continued to increase in 20 years,an increase of 894.49 km2 in 2015 than in 1995,an average annual increase of 0.4%.In addition,grassland and unused land area continued to decrease for 20 years,especially for unused land,by 590.61 km2,accounting for 80% of the total area of unused land(1995)and mainly converted into arable land and forest land.Although the water area changes slightly ups and downs,but the overall rate is not large.(2)The dynamic difference of land use in the study area in 20 years was obvious.In the case of single land use dynamic degree,the change of unused land is the largest,reaching-8% in 1995-2000;the second is the construction land,the change of the previous 10 years is greater than that in the last 10 years,and the whole is increasing year by year.And the woodland's annual attitude was less than 1%,while the former showed a tendency to increase slowly and then increase slowly,while the latter showed a slight increase trend.The grassland showed a decreasing trend year by year,and the change rate was greater in the last 10 years.In terms of comprehensive land use dynamic degree,the comprehensive dynamic degree of the three periods is less than 2%.Among them,the comprehensive dynamic degree of cultivated land,forest land,water area and construction land is less than 1%,and the comprehensive dynamic of grassland and unused land Which is between 1% and 2%,which indicates that the overall extent or intensity of land use change in the study area is not significant,but the change is obvious.(3)From 1995 to 2005,the largest amount of arable land was 783.26 km2,which was 2.36 times of the total amount of cultivated land.The substantial reduction of cultivated land area could not be neglected.From the type of arable land transfer,the first is the conversion to forest land,the number of 627.93 km2,accounting for 80.17% of the total area.Followed by the construction land,during which 112.38 km2 of the arable land into a construction land,accounting for 14.35% of the total area out.In terms of diversion type,the number of unused land and forest land was the largest,which was 140.00 km2 and 116.09 km2.2005-2015 respectively.1995-2015 of different land types in the study area are transferred into a large amount of land transfer type change obviously,and showed a trend of "three add,minus three",namely,woodland,waters and the increase of construction land,cultivated land,grassland and unused land reduced.(4)In the rapid urbanization scenario,the construction land has expanded sharply,doubling its area in 35 years to 1 390.46 km2,and the main source is cultivated land,accounting for about half of the area of cultivated land transfer;forest land grows slowly,grassland and unused land continue to decline,to 2050 were reduced by 186.58 km2 and 69.40 km2 respectively,the unused land reduced by half.In the planning scenario,the growth of construction land is still growing rapidly,increasing by 347.92 km2 in 2050,an increase of 37.92%;the decrease of cultivated land has damped down,and the increase of forest land is faster than that of rapid urbanization scenario,but the grassland and unused land continue to decrease,35 years were reduced by 25.9% and 44.3%.In the ecological protection scenario,the ecological land,such as forest land,grassland,unused land and so on,continue to recover and increase,by 2050,the total area of ecological land accounts for 64% of the study area;the construction land sprawl is limited,and its total area by 2050 for the 1 171.42 km2,compared with the same period rapid urbanization scenario reduced by 219.04 km2;although the reduction of arable land,it gradually tends to balance,and always remain above 6 000 km2.(5)The change of ecosystem service value of land use change in different scenarios of future study area is closely related to the change of land use type,that is,when the unit price of ecosystem service function is constant,the increase or decrease of land use type directly leads to its corresponding ecology The increase or decrease in the total value of the system services.In the next three scenarios,due to the change of land use in the study area,the trend of "three minus,two increases and one invariable" shows that the cultivated land,grassland and unused land are decreasing continuously,and the land and construction land are increasing continuously.Obviously,the corresponding value of ecosystem services also showed the same trend.However,the value of ecosystem services in ecological protection scenarios is the smallest,and the ecosystem service value of ecological land such as forest land,grassland and water is higher than that of the same period of "rapid urbanization scenario"," Planning scenario " should be large,the resulting ecological environment effect is also more obvious.Therefore,the ecological protection scenario is an ideal model for the coordinated development of economy,society and environment in the future.The results can provide scientific reference for land planning and regional sustainable development in the area. |
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