Ecological Response To Wetland Landscape Pattern Change Based On In VEST Model

Wetland in southern Hangzhou Bay area is mainly located in the northern region of Cixi City, this area had a large richness of habitat and species types. However, in recent years, due to the social and economic development and urbanization continuing to spread, there had been many environmental issues such as a decline in habitat quality, degradation of ecosystem, and any others. With the continuous reduction of wetland area, various biological resources based on wetland ecosystem were disappearing gradually, and biodiversity at risk. The existence and development of Hangzhou Bay is facing more and more serious challenges.This paper selected Landsat5-TM remote sensing images of southern Hangzhou Bay area in the year of2000and2010as basis data, and interpreted remote sensing images in use of remote sensing processing software, Erdas Imagine9.2, to obtain information of landscape types and generate maps of landscape types in these two periods. Use landscape pattern analysis software, Fragstats3.3, to calculate landscape pattern indices, and analyze the characteristics and changing rules of landscape pattern in the study area systematically and comprehensively with landscape dynamic degree, landscape pattern indices and the transfer matrix of landscape area, then explore the changes in land-use patterns. On this basis, evaluate the ecological environment quality of southern bank of Hangzhou Bay comprehensively in use of Biodiversity module, part of InVEST model, to get the characteristics of spatial changes of habitat degradation, habitat quality and habitat rarity in study area from2000to2010, then explore the ecological response to wetland landscape pattern change further.The main conclusions of the study are as follows:(1)The main landscape types in southern Hangzhou Bay area are dryland landscape and wetland landscape, while the main types of wetland landscape were paddy landscape and shallow coastal water; Of the wetland, urban and rural settlements also occupies a large proportion, except dryland landscape. From2000to2010, structural changes in the landscape of southern Hangzhou Bay area were significant. Due to recent coastal reclamation, the area of dryland landscape had a substantial increase, however, the areas of coastal beaches and coastal marshes as wetland reduced rapidly, and total area of wetland declined. With the acceleration of urbanization, area of urban and rural settlement also showed a high growth momentum, and area of woodland landscape declined.(2)By analyzing the landscape indices indicates that, the landscape in southern Hangzhou Bay area had a high degree of fragmentation as a whole, and patches had complex structures. From2000to2010, degree of overall fragmentation of the landscape in the study area further improved, patch shape tended to be stable. In the types of wetland landscapes, except coastal beach,the degree of fragmentation of others improved by different extent. Due to the ongoing transformation of other types of landscapes to construction land, the spatial agglomeration of urban and rural settlements greatly improved, with the degree of fragmentation declining. With the interfere of the surrounding urban and rural settlements and dryland landscape, the degree of fragmentation in woodland landscape improved greatly.(3)By analyzing the transfer matrix of landscape areas can be drawn that, shallow coastal water, dryland landscape and urban and rural settlement had a larger area rolling in, while the area of coastal beaches, coastal marshes and other natural wetland larger roll out in all types of landscapes in southern Hangzhou Bay area from2000to2010. Despite the circumstances that all other types of landscapes transferred into dryland landscape and urban and rural settlement, the main transfer source of both landscape types were wetland landscapes, including coastal beach, coastal marsh and paddy landscape. Paddy landscape had a great rolling-in and rolling out, and the main source was coastal beach,the main whereabout was dryland landscape. Woodland landscape had a large rolling out, mainly to dryland landscape. In summary, the landscape pattern of the southern Hangzhou Bay area showed a trend of natural wetland to artificial wetland and wetland to non-wetland.(4)Analyze the ecological response to wetland landscape pattern change by combining changing characteristic of landscape pattern and evaluation results of ecological environment quality. The results showed that, due to the impact of the increasing degree of fragmentation in overall landscape, the southern Hangzhou Bay area increased area of habitat degradation, and habitat quality tended to decline. As urbanization spread to the east coast, the area of urban and rural settlements increased rapidly in eastern region, causing high scores zones of habitat degradation eastwards; Due to large reclamation of coastal land and beaches, area of coastal beach and coastal marsh decreased greatly, transforming into dryland and urban and rural settlement, where the degree of habitat degradation increased, habitat quality declined and habitat rarity presented a high score status. The degree of habitat degradation in southeastern and coastal areas turned worse seriously. Internal area of woodland landscape maintained a fine degree of habitat degradation and habitat quality, but the degree of habitat degradation and habitat quality in the fringe area declined evidently, presenting a high habitat rarity. This was primarily because of the deforestation causing woodland transforming to dryland, patches of woodland divided and original habitat destructed.