一种新的景观扩张指数的定义与实现

景观格局动态信息的定量表达始终是景观生态学研究的一个重要科学问题,景观格局指数是其中的一种重要方法,但其多是静态指数,难以有效定量表达景观格局的动态信息.因此,针对景观扩张过程以斑块扩张面积为基础提出了一种新的景观扩张指数,来表达景观格局的动态信息.并以妫水河流域1998-2009年的景观农田化过程为例,验证该指数的适用性,结果表明:该指数不仅能够定量表达斑块的空间扩张规模,而且可以准确识别斑块的空间扩张模式.根据扩张斑块与原斑块的空间位置关系,将景观的空间扩张模式划分为邻接扩张式和外部扩张式两种.提出的景观扩张指数在技术方法上计算简便,易于实现,完善了景观格局动态的量化表征科学方法.

A new landscape expansion index: definition and quantification

Landscape patterns, processes and functions are the main contents of landscape ecology, and they are interdependent and interacting. Landscape patterns and their dynamics has always been an important scientific issue of landscape ecology. Landscape pattern index is the most widely used method among the existing research methods in landscape patterns, despite its suffering from doubt and its limitations. The majority of the existing landscape pattern indices only explain landscape spatial characteristics in different scales from geometrical characteristics, they all fall into the category of static index, and can not indicate landscape dynamic information. Studies of landscape pattern dynamics are mainly through multi-temporal comparison of landscape pattern indices and variety of dynamic models. Landscape pattern indices can not independently indicate landscape dynamic information yet. So this paper presents a new landscape expansion index (LEI) to indicate landscape dynamic information, this index is based on expansion patch area and weak the impact of patch shape, and this LEI is calculated only with ArcGIS and EXCEL software. The spatial expansion patterns of landscape are divided into adjacent expansion pattern and external expansion pattern based on the spatial relationship between the expansion patch and the original patch. The fundamental difference between the external expansion pattern and the adjacent expansion pattern is the changes of patches area and number. The adjacent expansion pattern increases the area of patches, whereas the external expansion pattern increases the number of patches. LEI's value can be used to accurately identify expansionary patches' spatial expansion patterns, only when A₀ = 0 and the original patch that is adjacent to the expansion patch does not exist, the LEI = 1, and the spatial expansion pattern of patches are external expansion pattern; when the LEI is equal to other values, the spatial expansion pattern is adjacent expanding pattern. Furthermore, this LEI is used to the process of landscape's changing to farmland in Guishui river basin from 1998 to 2009 to verify its applicability. Results show that this index can not only quantitatively indicate spatial expansion size of patches, but can also accurately identify the spatial expansion pattern of patches. Therefore, this paper argues that this landscape expansion index has a prospect for wide application.