| In the past 40 years,China's urbanization has made great achievements.Various ecological and environmental problems caused by “large edge-expansion” and blind and disorderly expansion are common.In the next few decades,it will still be a period of rapid urban expansion.The growth of construction land will encroach on a large amount of ecological land,especially wetland.Poyang Lake Ecological Economic Zone has a large area of wetlands,and the rapid growth of construction land has a significant impact on the wetland environment of the entire region.This article uses this area as a research area.First,the landscape expansion index(LEI)is used to analyze the growth of construction land from1995 to 2015.And the morphological spatial pattern analysis(MSPA)is used to analyze the changes of wetland in various periods.Secondly,the occupation of natural wetlands and artificial wetlands by urban expansion is analyzed.The wetland landscape fragmentation,connectivity and complexity,calculate the correlation between construction land growth and landscape index,and explore its impact on wetland landscape;Finally,establish an ANNCA model to predict the growth of construction land in 2030,so as to analyze the changes of wetland quantity and spatial distribution caused by urban expansion from 1995 to 2030.The conclusions of this study are as follows:(1)From the perspective of the changes and expansion patterns of urban expansion in the study area,the edge-expansion is the dominant type,the infilling is the second,the outlying has the smallest area,and the areas with the fastest growth in construction are mainly around the central urban areas.the more close to the central city construction land increase more.Computing MLEI and AWLEI value of research area and each city,both of them show an upward trend,indicating that the expansion of the Poyang Lake Ecological Economic Zone and its branch cities has become more concentrated.compactness and higher land utilization.(2)From analysis of the change of wetland from 1995 to 2015.and the paddy field area was the largest in the whole study area,and the total wetland area is decreasing year by year.Analysis of its landscape pattern reveals that the core has the largest proportion and the largest area,but the area gradually decreasing,the area of small landscape patches is increasing,indicating that the wetlands in the study area are becoming more fragmented,the connectivity is decreasing,and the whole wetland has evolved in a direction of more fragmentation.(3)From the perspective of the impact of urban expansion on wetland landscape during the study period,the expansion of construction land occupied a total of 7.29 km2 of wetland area,of which 5.48 km2 was artificial wetland and 1.81 km2 natural wetland.Construction land occupied more artificial wetland,and Nanchang occupied the largest area of the two types of wetlands.;and the expansion of urban construction land in Poyang Lake Ecological Economic Zone is highly related to changes in wetland landscape patches.The expansion of construction land caused the wetland landscape patches in the study area to become more fragmented,connectivity decreased,and the patches became more complicated and irregular.(4)Judging from the change of construction land in the forecast results,the area of construction land in each city of Poyang Lake Ecological Economic Zone has increased,and the areas of construction land in Nanchang,Jiujiang and Yichun have increased the most,indicating that the overall urban development direction in the future tend to these three cities,and construction land increase mainly around the construction land in 2015.(5)According the predicted construction land growth occupied wetlands,urban expansion will occupy wetland landscapes,and the main type of wetland occupation is artificial wetland,which occupies less natural wetlands;the change trend is basically consistent with the growth trend of construction land.This shows that the faster the construction land increases and the more the area increases,the more wetland landscape area be occupied. |
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