1996-2006年美国海岸带土地利用/土地覆被变化时空动态研究

Spatial-Temporal Dynamics of Land Use and Land Cover Change From 1996 to 2006 in the Coastal Zone, USA

人类活动深刻影响着美国海岸带地区,其中一个很重要的方面表现为多时空尺度的土地利用/覆被变化。本文基于NOAA Coastal Services Center提供的1996年、2001年和2006年土地覆被数据,将美国本土海岸带分为五个子区域:五大湖沿岸区(LC)、西海岸区(WC)、墨西哥湾海岸区(GC)、东北海岸区(NC)和东南海岸区(SC),对其土地利用/土地覆被变化的时空特征进行研究。结果表明,研究期内美国海岸带地区林地持续大幅减少同时在SC和GC湿地数量明显下降,而且1996-2001年较2001-2006年土地面积变化更为剧烈。除了在WC最主要的三种用地类型为林地、草地和耕地,其他4个子区则均为林地、湿地和耕地。自1996-2001年到2001-2006年,土地变化幅度明显放慢,用地结构较稳定,其中美国西海岸用地结构最稳定。林地和草地的相互转化在海岸带区域比较普遍,在SC还发生了明显的湿地与林地间的相互转换。美国海岸带的土地利用程度整体较高,其中以LC数值最高、人类活动程度最强,而WC则最小。

Human activities have impacted on the coastal zone profoundly;one of the most important aspects was the land use and land cover change that happening on multi-spatial-temporal scales. In this paper, based on the land cover data in 1996, 2001 and 2006 derived from NOAA Coastal Services Center, the spatial-temporal characters of land use and land cover change in USA’s coastal zone were studied. It’s divided into five sub-regions which are: Great Lakes Coast (LC), West Coast (WC), Gulf Coast (GC), Northeast Coast (NC) and Southeast Coast (SC). Statistical methods and GIS techniques were used to analyze the spatial-temporal characters of LUCC. We found that, there’re extensive land-use activities accompanied with substantial shrinkage of forest area in all the five sub-regions as well as significant decreasing of wetland in SC sub-region, and the change of land areas in 1996-2001 was more dramatic than in 2001-2006. Forest land, wetland and cultivated land were the dominant land use types in most area of coastal zone in USA, however, the grassland spread much wide in WC sub-region. From 1996-2001 to 2001-2006, the changing speed was mitigated markedly, therefore the land cover structure was relatively stable in coastal areas and WC was the most stable. Interchanges between forest and grassland were much common process in coastal zone;moreover, interchanges between wetland and forest were significant in SC sub-region. The land use degree was high overall coastal zone in USA and, from the perspective of land use degree index, LC sub-region has the most intensive human activities while WC sub-region, the least.