| Under the circumstances that the scarcity of natural resources and environmental pollution is critical,it is of great significance to study the future development trends of regional ecological environment.Taking Qianjiang City as an example,this paper analyzed its land use change,calculated the Ecosystem Services Value(ESV),drew the ESV spatial distribution grid map,and probed its Spatio-temporal variation characteristics based on RS and GIS from 1995 to 2015.The land use spatial pattern of Qianjiang City in 2035 was simulated through CA-Markov model among multiple scenarios,in which different land use pattern and ESV development trends from 2015 to 2035 were explored.The results showed that:The land use structure of Qianjiang City was mainly composed of cultivated land,followed by construction land,water and forest,while grassland,wetland and other important ecological resources were seriously scarce.From 1995 to 2015,the number of construction land increased sharply,and cultivated land increased slightly,while the number of other types of land use decreased rapidly.The outflow amount of cultivated land and construction land was the smallest,while the inflow amount was the largest.Grassland outflow was the largest,and woodland,water,wetland outflow was large as well.The inflow amount of forest and grassland was low,and the amount of water and wetland was the least.The total ESV dropped significantly,and the ESV of different land use types was considerably different.The value of water and cultivated land was the highest,followed by woodland,wetland and grassland,and the value of construction land was negative.The value of cultivated land not only maintained a high level,but also showed an increasing trend.The value of woodland,grassland,wetland and water had decreased.The quantity of wetland decreased the most,while the amplitudes of water area decreased the most.The quantity change of water area was the main reason for the fluctuation of the total ESV in Qianjiang City.The high ESV area mainly clustered in the vicinity of lakes where water resources was abundant,while the low ESV area mainly distributed in urban areas and cultivated land.From 1995 to 2015,all levels of ESV,except grade 2,had a trend of gradually spreading from the original aggregation area to the surrounding area.From 2015 to 2035,under the natural development scenario,construction land,water area and wetland in Qianjiang City expands substantially,while other land use types areas continue to decline.As the value of water increases sharply,ESV rises quickly.The pressure on woodland and grassland is reduced.However,industrial mines,cities,towns,shrimp ponds and fish ponds continue to occupy cultivated land,endangering regional food security.Under the scenario of ecological environment protection,construction land continues to expand,and water begins to decrease instead of increasing,but the reduction is not significant.The scale of woodland,grassland and wetland increases year by year.The deceleration of cultivated land is greatly reduced compared with the natural development scenario,and the ESV is slightly reduced.The quality of ecological environment has been improved,compared with natural development scenario,and the threat to cultivated land has been significantly reduced,besides,the speed of water expansion has been effectively controlled.Under the scenario of cultivated land protection,similar to the scenario of ecological environment protection,the area of woodland,grassland and wetland is increasing,and the increase rate is rising.The difference is that the cultivated land resources are no longer lost,but the decrease rate of water area is expanding to 22%,and the increase rate of construction land is decreasing.As a result,the total ESV is slightly decreasing.Provided the importance of water ecology to the whole ecosystem of Qianjiang City,the water loss of 248 hm2 per year is a major hidden danger.And slow growth of construction land will hinder the economic development of Qianjiang City. |
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