| Under the background of urbanization development,how to effectively and reasonably assess land use changes,the temporal and spatial evolution characteristics of regional habitat quality and the internal driving mechanism of its evolution,as well as the prediction of future land use and habitat quality evolution trends,is the basis for scientifically protecting the ecological environment and rationally planning land resources.It is also a key issue that needs to be resolved urgently for the coordinated development of high-quality cities.Take the Ecological Urban Agglomeration around Poyang Lake as a case,the spatial structure and temporal evolution law based on the habitat quality of the district unit have been discussed with the help of a In VEST model respectively to assess the habitat quality of Ecological Urban Agglomeration around Poyang Lake in 2000,2010 and 2017,which is based on the exploring the characteristics of the spatio-temporal evolution of land use from2000 to 2017 through the change and transfer of land use quantity.In addition,combining natural,social,economic and accessible factors,the driving mechanism of the habitat quality evolution of the Ecological Urban Agglomeration around Poyang Lake has been investigated by using geographic detectors.Furthermore,a Markov-FLUS coupling model is built to simulate the land use change of the Ecological Urban Agglomeration around Poyang Lake in 2031.Further carrying out the multi-scenario simulation and prediction of habitat quality,so as to fully grasp the evolution trend and spatial distribution law of the habitat quality of the Ecological Urban Agglomeration around Poyang Lake,and puts forward the corresponding coordinated development strategy.The results show that:(1)From 2000 to 2017,the main land types of the Ecological Urban Agglomeration around Poyang Lake are forest land and cultivated land.The construction land area has expanded by 2054.51 km~2,while the forest land,arable land,water area and unused land have separately reduced by 911.21 km~2、884.23 km~2、437.96 km~2 and 411.80 km~2.The main ecological land(forest land,water area,grassland)has reduced by 758.63 km~2.It is necessary to strictly limit the occupation of basic farmland and cultivated land.The main characteristics of land use transfer are as follows:the expansion of construction land is the most significant,and the area of cultivated land transferred in is much smaller than that of cultivated land transferred out.Among them,1,330.35 km~2 of arable land,690.89 km~2 of woodland and 94.12 km~2 of grassland are converted to construction land.814.43 km~2 of cultivated land area is transferred to forest land and water area.Due to the implementation of the cultivated land protection policy,1109.77 km~2 of forest land and water area are also converted to cultivated land.(2)The degradation degree of the habitat quality of the Ecological Urban Agglomeration around Poyang Lake has respectively increased by 3.33%from 2000 to2010 and 4.14%from 2010 to 2017.From a spatial perspective,the degradation degree presents the characteristics of circle layers.The high-value area of the degradation degree shows a gradual decreasing trend to the periphery,while the low-value area is the opposite.From 2000 to 2017,the overall habitat quality in the study area is generally good,with excellent and medium grades as the main ones,followed by good grades,and poor and very poor habitat quality accounting for less than 10%of the total habitat quality.The area of poor habitat quality increased by 2059.43 km~2,an increase rate of 2.24%;Secondly,the quality of medium and excellent habitats have decreased by 1556.34 km~2 and 1209.15km~2 respectively.Based on the evolution of habitat quality in district units and space partition,the overall habitat quality shows a decreasing trend from 2000 to 2017,but the districts in the high-value areas and low-value areas remained stable,and the average value of the habitat quality in each district has decreased.From the perspective of time,the average value of habitat quality in each district in 2000 is 0.697,and the average value in 2017 is 0.671 with a decrease of 0.026.The districts with excellent habitat quality in 2000 are mainly Tonggu County,Wuyuan County,and Fuliang County with average values of 0.942,0.909,and0.889 respectively.Nanchang City,Nanchang County and Yingtan City have poorer habitat quality with the mean values of 0.430,0.447 and 0.480 respectively.The low-value areas of the Ecological Urban Agglomeration around Poyang Lake mainly include 18districts in Nanchang-Jiujiang Metropolitan Area and its surrounding linkage areas with an average value of 0.512.The median habitat quality area is the 14 districts surrounding the metropolitan area,and the average value of the habitat quality index is 0.663.The high-value habitat quality areas are 25 districts in the west and east mountainous regions including Fuliang County.The habitat quality is high at 0.789.However,the habitat quality level has been declining from 2000 to 2017 and some areas turn from high to median value.(3)The detection results from geographic detector show that most of the 14 factors have significant differences between every two.The five factors that have the strongest explanatory power for the evolution of habitat quality are as follows:land use>elevation>slope>temperature>population density.The q value of the land use factor is much larger than other factors,indicating that the land use factor(X1)can better explain the spatial variability of habitat quality and is highly consistent with the spatial distribution of habitat quality.The significantly enhanced interaction results are still the interaction between land use(X1)and other driving factors.The largest value is land use factor(X1)and elevation factor(X2).The interactive exploration explanatory power is 0.78;Slope(X4),rainfall(X5)and accessibility factors(X9-X14)are the weak explanatory factors.Each factor has the most significant interaction with land use driving factor.It can be seen that the spatial distribution of land use types determines the spatial difference of different habitat quality,which is a prerequisite for the temporal and spatial evolution of habitat quality;Elevation,slope,temperature,and population density have the second effect.(4)There are obvious differences in the distribution of simulated 2031 habitat types under different scenarios.Under the natural development scenario,construction land will expand by 2075.10 km~2 from 2017 to 2031 with an increase rate of 50.60%;the area of woodland and arable land will separately decrease by 1,470.78 km~2 and 869.75 km~2.Under the arable land protection scenario,the area of arable land will increase by 741.47 km~2compared with the natural development scenario due to the protection of arable land resources,while the area of construction land will decrease by 539.64 km~2.Under the ecological security scenario,forest land will increase by 810.66 km~2 and construction land will reduce by 719.01 km~2 compared with the natural development scenario,and forest resources would have protected effectively.In 2031,the main habitat quality structure will be excellent and medium under the natural development scenario,accounting for 39.32%and 34.71%respectively.Under the arable land protection and ecological security scenarios,it will be better than the natural growth scenario.The area of poor habitat quality will reduce by 721.77 km~2 and 539.3 km~2 respectively.The average value of the habitat quality of the Ecological Urban Agglomeration around Poyang Lake and the average value of each district show a decreasing trend from 2017 to 2031.The average value of the whole area in 2017 is 0.670,and it will decrease to 0.642 by 2031.The ecological security scenario is more conducive to the sustainable development of habitat quality.(5)In response to problems,such as the rapid growth of construction land,the lack of protection of cultivated land resources,the continuous degradation of habitat quality,and the large differences in spatial distribution that existed in the rapid development of the Ecological Urban Agglomeration around Poyang Lake,a district management model is adopted.For the low-value habitat quality of Nanchang-Jiujiang Metropolitan Linkage Area,the main purpose is to guide the orderly gathering of construction land to build the ecological land space within the city,to strengthen the joint improvement of water resources to ensure the safety of ecological land use in the water area.For the middle-value area of habitat quality surrounding the metropolitan area,it is mainly to reduce the occupation of arable land resources,strengthen the prevention,control and management of agricultural land pollution,build a green ecological zone in the outer circle of the metropolitan area.For a high-value habitat quality area in the west and the east,it is mainly to raise the threshold for high-polluting industries,strengthen the protection of natural ecological land of forest land. |
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