Temporal and Spatial Evolution Characteristics and Ecological Risk Assessment of Land Use Landscape Patterns in Central Zhejiang Urban Agglomeration

As the carrier of regional urban development, land has been attached great importance to spatial planning and development policy. In order to explore the sustainable development mechanism of "land use-ecology" in the middle-eastern urban agglomerations in the southeast coast, taking the central Zhejiang urban agglomeration as an example, the FRAGSTATS was used to measure the landscape fragmentation index of the central Zhejiang urban agglomeration by analyzing the five remote sensing image data from 1996 to 2016, including the horizontal value of the key time nodes of landscape shape index and landscape diversity index, and the evolution characteristics of the comprehensive landscape structure of the land use in the study area; and then the land use ecology of the central Zhejiang urban agglomeration in different periods was analyzed through the ARCGIS evolution regional ecological risk spatial differentiation. It was found that from 1996 to 2016, the transfer situation between various types of land use was significantly enhanced. The area of construction land was increased by nearly three times; the proportion of forest land area showed a slow growth trend; the land area of water resources and water conservancy facilities was decreased from 5.85% to 3.89% in 2006-2016, with a large decline; the unused land was reduced by nearly 21a. The most common ratio was followed by cultivated land. The actual reduced area of cultivated land was more than that of unused land. In the field and grassland, it was mainly distributed in the northeast direction and northwest direction of the central Zhejiang urban agglomeration. The overall increase in grassland was generally reduced. Increased and reduced areas account for a small proportion of total land use area. The overall landscape pattern quality of land use in central Zhejiang urban agglomerations showed a trend of "first decline-then rise-overall decline". The specific performance was as follows: from 1996 to 2016, the overall landscape fragmentation index was increased, and the local year was declined. The landscape shape index and landscape diversity index were decreased overall, and the local year was increased. The transfer of various types of land tended to be complex and volatile. Based on 2016 time node spatial evolution characteristics of the horizon to ecological risk analysis of middle of Zhejiang, the ecological risk index of Yiwu, Dongyang and Wuyi was between 0.69~0.82, for Ⅳ and Ⅴ level areas, ecological risk level was high or higher; the ecological risk index of Wu City, Jindong Area and Pujiang County was between 0.56~0.59, for Ⅲ level area, ecological risk was moderate; the ecological risk index of Lanxi City, Yongkang City, Zhuji City, Panan County, Longyou County and Jinyun County was below 0.49, for Ⅰ or Ⅱ level, ecological risk level was low or relatively low. From 1996 to 2016, the spatial risk of land use ecological risk grades in central Zhejiang urban agglomerations was quite different, and the spatial distribution showed the phenomenon of "convergence club" and "concentration-distribution", that was, higher ecological risk. The area and high ecological risk area were spatially directed to the central part of the middle-middle urban agglomeration and there was a gathering situation; the lower ecological risk area and the low ecological risk area were spatially dispersed in the northwest, southeast and southwest areas of the Zhejiang city group. The research and judgment of the sustainable use of land in central Zhejiang urban agglomeration provided ideas and methods to promote the sustainable development of land use and ecological environment in central Zhejiang urban agglomerations. © 2020, Chinese Society of Agricultural Machinery. All right reserved.