| Based on land use data in coastal zone in mainland USA in 1992,2001 and 2011,which were created and shared by USGS,characteristics of coastal land use change in mainland USA were studied by means of multiple index models.The results show that:(1)The diversity of coastal land use in mainland USA is prominent.Forest is the most widely distributed land use in the whole coastal zone in mainland USA,followed by shrub,grassland and open water area successively.The other types have limited area and proportion,while the perennial ice and Snow Belt could be found in the west coast area only.(2)During 1992 to 2011,forest land reduced greatly,and mainly changed into developed area,shrubs and wetlands.The grassland mainly converted into crop cultivation area,while amount of crop cultivation area converted into grassland was more significant.Significant inter-conversion between forest land and grassland was observed.And significant increment of developed area was observed,which was ceaselessly converted from woodland,grassland and the others,while the reversed conversions were trivial.(3)Increase of the land use diversity in coastal zone in mainland USA could be observed,although it's a little bit slowly as a whole.And,the increase was much more significant in coastal zone in the Gulf of Mexico while very insignificant in the West Coastal Zone.Frequency of interconversions among various types of land use presented sequential features as Northeastern Coast> West Coast> Southeast Coast> Gulf Coast> Florida> Great Lakes Coast.Overall,the land use type changed more frequently between 1992 and 2001.Ecological land is a sensitive type of land use in rapid urbanization.Ecological connectivity is an important way to study the relationship between landscape structure and landscape function.Using the land use data of the New York metropolitan area from 1992 to 2001 to evaluate the ecological connectivity of ecological land,we try to identify the important regional patches that maintain the overall ecological connectivity in space.The results show that:(1)From 1992 to 2001.The global connectivity of ecological land in metropolitan area in New York City has been on a downward trend,with a slight increase from 2001 to 2011 only.The downward trend is especially noticeable around 2000,while that of shrubs,wetlands and development zones is relatively high,and that of wasteland,woodland,cultivated crops The rate of area decline is larger.The process of urbanization makes the regional ecological land increasingly fragmented,resulting in great changes in the ecological connectivity of the study area,which has a greater impact on the ecosystem.(2)The application of BEI to the New York metropolitan area shows that at least 56.5% of metropolitan areas are adversely affected by man-made obstacles.The New York metropolitan area has a value range of(1,139)In the western part of New York,the ecological connectivity in the western part of the metropolitan area is superior to that in the eastern part.(3)From 1992 to 2011,the overall ecological connectivity of New York metropolitan areas showed an increasing trend,and the ecological function areas expanded from the northeast to the southwestern regions.The ecological connectivity of the metropolitan clusters centered on New York decreased first and then slightly There is a tendency of recovery.After the substantial expansion of urban construction land,the government has introduced various policies to ease the encroachment and obstruction of ecological land due to urban expansion.Evaluating the ecological connectivity of land use and planning in rapidly urbanizing areas and providing decision support for land management have become the inevitable choice to ensure the ecological security of land in the region. |
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