Connectivity Measurement in Landscape Ecology

NRS 534: Ecology of Fragmental Landscapes Yuyu Zhou Spring 2005 Overview Connectivity refers to the degree to which a landscape facilitates or impedes ecological flows such as the movement of organisms among habitat patches and therefore the rate of movement among local populations in a metapopulation (McGarigal et al. v3). Although connectivity is important in landscape ecology, there is no precise definition and it is difficult to quantify and imply because of the difference that it is processed as an independent or dependent variable, and structural or functional variable. Goodwin gave a good review about the connectivity research. According to this paper, studies of landscape connectivity are divided between those that seek to understand how landscape structure and movement behavior interact to dictate connectivity and those that seek to evaluate the impact of connectivity on other ecological processes (Goodwin 2003). With the limitation of the knowledge and method, most present researches process connectivity as independent variable. Therefore, connectivity is mainly discussed as an independent variable in this paper. Furthermore, according to another standard, connectivity measurements can be divided into direct and indirect ones. Direct measurements must incorporate a measure of some aspect of organism movement through the landscape. For the direct method, connectivity can be measured as the probability of movement between two source patches, dispersal success and search time. Landscape indices that characterize the spatial pattern of a landscape are common indirect method. In the following parts, the data, methods (independent or dependent) and tools for the connectivity measurement will be discussed.