基于梯度分析的福建典型沿海港湾区域景观格局研究

Gradient Analysis of Landscape Pattern in Louyan Gulf Region in Fujian Province

运用景观指数与梯度分析相结合分析福建省典型港湾区域-罗源湾区域近20年来的景观格局及其时空梯度,定量描述人类活动行为与区域景观格局时空变化的联系。基于景观指数的景观格局分析表明：1988年-2007年期间罗源湾区域总体景观格局破碎度呈明显的增加,景观结构的复杂化趋势明显。梯度分析结果显示,1988年-2007年县城中心及其附近的斑块密度、景观形状指数高于两侧的乡村区域,景观破碎度、景观组分复杂度呈明显的空间梯度;建设用地景观的最大斑块指数、平均斑块面积、斑块连通度以县城中心及其附近为最大,并向外围两端的乡村递减;1988年-2007年水体景观因围海工程而斑块密度、最大斑块指数、平均斑块面积和斑块连通性指数值呈下降趋势。罗源湾县城中心的城市化作用与围海造地的政策因素是促使研究区域景观格局具有明显的时空分异的两大驱动力。

Land use and land cover change （LUCC） has received attention in recent years due to its important role in global and regional environmental change. The spatial pattern of land use reflects underlying human activities including urbanization process and policies developed for social and economic development at local to regional scales. The quantification of landscape pattern is a prerequisite for the identification and evaluation of temporal changes, and for the study of the effects of pattern on ecological processes. Landscape pattern metrics are an important characteristic for evaluating the ecological processes and effects of land use. A large collection of indices have been developed to describe landscape pattern, and these indices have proved useful for the description of landscape structure and its spatial-temporal dynamics. Gradient analysis has also proved to be a useful and necessary tool for studying the ecological consequences of urbanization, since the direction and magnitude of landscape change could be different for urbanization processes in particular regions. In this study, gradient analysis was integrated with landscape pattern metrics to characterize the spatial-temporal landscape pattern and quantitatively describe the relationship between human activities and ecological processes over the period 1988 to 2007 in a coastal gulf region in southeast China. Three years of Landsat TM images, from 1988, 2002, and 2007, were interpreted to obtain land-use datasets. Based on the analysis of the whole gulf region using landscape Gradient analysis shows distinctive spatial differences in landscape fragmentation and landscape structure from the urban center to rural. At the landscape level, landscape pattern metrics including Patch Density （PD） and Landscape Shape Index （LSI） have higher values in urban centers than in rural areas. As for the built-up land class, the spatial gradient demonstrates that landscape pattern metrics including Largest Patch Index （LPI）, Mean Patch Size （MPS）, and Patch Cohesion Index （COHES） tend to decrease from county center to rural area. For water bodies, due to the policy called ＂Transferring Seawater into Built- Up Land,＂ landscape pattern metrics including PD, LPI, MPS, and COHES tend to decrease over the period 1988 to 2007. Urbanization processes and this development policy are found to be the two driving forces leading to the spatial-temporal landscape pattern in Louyan gulf region during 1988 to 2007.