1.3.2 Nearshore Landscape Ecology |
Landscape ecology addresses how the spatial extent, heterogeneity, and geometry of landscape elements (e.g., habitats) affect the flow of energy, biota, and materials through the landscape. Human activities are fragmenting natural landscapes into fewer and smaller pieces at an alarming rate, reducing the flow of these materials among habitats and causing local extinction of some populations (Weins 1985; Gonzales et al. 1998; Earn et al. 2000). However, it is clear that most elements of a landscape function best when integrated with all other elements (e.g., watershed approach), and restoration projects are now utilizing the concepts and principles of landscape ecology to improve the functions and success of restoration projects (Kentula 1997).
Of particular relevance to estuarine and marine nearshore ecosystems are the landscape concepts of habitat size, shape, and accessibility (Simenstad and Thom 1992; Shreffler and Thom 1993; Simenstad and Cordell 2000; Bottom et al. 2001). Knowledge of the behavioral patterns of target species or species groups is essential to refining the site selection and design process for management decisions, such as a restoration, for a particular habitat. The National Research Council (1992, 2001) recommends that systems should adopt a dynamic perspective that considers current and future conditions at the site and in the surrounding landscape. A dynamic, landscape oriented approach could mean preserving riparian zones and connectivity to other habitats around a particular site.
On Bainbridge Island, the marine nearshore landscape encompasses the interface between subtidal marine habitats and the upland watershed (including the riparian zone), which is shaped by alongshore processes that affect sediment transport and aquatic species movement patterns. It is apparent that these shoreline processes must continue to function appropriately across the entire landscape to manage shoreline habitats and ecological functions in a long-term, self-sustaining condition (Williams and Thom 2001;Best 2003). With this in mind, the assessment was designed to examine impacts to nearshore processes at two landscape scales. The larger management area (MA) is scaled to encompass aggregations of alongshore cells, analogous to upland watersheds, which define sediment transport processes that form the primary basis for establishing and maintaining habitat structure and function (Figure 1). A management area is comprised of multiple reaches, which are scaled to current or historic geomorphic conditions. Geomorphology often defines or is commonly associated with distinct biological communities (e.g., halophytic plant assemblages in marsh and lagoon settings).
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