| Ecological network has been the hotspot in many fields like Conservation Biology, Landscape Ecology, Environmental Ecology, Urban Planning and Design and Land Use Planning. Ecological network is the collection of species habitat networks from the perspective of ecological functions. Habitat network provides important protection spaces for species to exchanging material, energy and information. However, in rapid urbanization areas, species habitats have been severely damaged with the dramatic changes in land use. Therefore, to research habitat network problems in rapid urbanization areas has more important significance on maintaining biodiversity and promoting the ecological network optimization.At present, most research has concentrated on planning and implementation of ecological networks through developing, assessing and optimizing ecological networks by the identification of patches and corridors and calculating the network connectivity. It’s less to consider time scales and study from the perspective of ecological network along with the change of land use. The existing domestic research involving the impact of land use change on habitats is mostly of general conclusion that land use change has caused habitat degradation. It’s lack of quantitative analysis and less with the specific species. In addition, in terms of optimizing ecological networks, the most commonly used method that built ecological networks was the least-cost path, less combination of different methods.Based on the view of the above, this paper selected Su-Xi-Chang area which was rapid urbanization area and had dramatic changes in land use as the study area and based on the land cover data in the year of 2000,2005 and 2010 of the study area. This paper took Egretta garzetta as the study species and got its habits through searching relative literatures. Then using spatial analysis tools in ArcGIS 10.1 could generate Egretta garzetta’s habitat network. Afterwards, this paper selected landscape indices and network structure indices from the perspective of patches and networks to analyze the impact of land use change on ecological network. On the basis of Restoration Ecology, this paper took the ecological network in 2010 as the present situation and the ecological network in 2000 as the optimized target and combined two different network-building methods, that is, identified the lost nodes in 2000 which on the least-cost paths and the cross-nodes of the least-cost paths as the restorative and newly-added habitat nodes, then assessed their importance and selected more important nodes to restore or add, finally got the best optimized ecological network. All those work could complete in ArcGIS 10.1、Fragstats 4.1 and UCINET 6.The results shows that:(1)the quality of the habitat network was decreased seriously due to the strong negative effect of newly-built constructions, such as expressways and high-speed railways, during the period from 2000 to 2010; (2) the habitat network of Egretta garzetta was only a small part of the whole area which consisted of four separate fractions. They were Yixing-Liyang Part, Binhu Part, Wuzhong Part, and Yangchenghu Part and ranked down respectively, according to their conditions of 2000. Their extent of damage appeared the similar trend; (3)most of the restorative nodes were small habitats which area were between 10 and 50 hm2; (4)the land-use types of restorative and newly-added nodes were arboreal forest or lakes and rivers that met the requirement of Egretta garzetta’s habitat; (5)after the process of optimizing network, we got the optimal network which has the best network structure and it could be the final optimized habitat network of Egretta garzetta in Su-Xi-Chang area. |
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