An Ever-Shifting Mosaic: Landscape Ecology Applied

Abstract

Landscapes are filled with patterns. Consider figure 9.1, a satellite image of the Mississippi River as it flows along the border of Arkansas and Mississippi south of Memphis, Tennessee. Equally striking are the sinuous course of the river and the grid of farms that surround it. Landscape patterns result from processes-in this case the erosion and deposition of sediments along the river's banks and the clearing of land for agriculture along property lines determined by the Public Land Survey System. Patterns also influence processes. The array of oxbow lakes formed from the river's meanders creates a series of wetlands that guide the movement of waterfowl through the region. The checkerboard of farms isolates small pockets of woods whose microclimates are influenced by their proximity to open fields. Neither of these two dominant landscape elements can be understood without reference to the other. The farmlands along the river are subject to periodic flooding. The river, in turn, is filled with water, sediment, and nutrients that run off the fields. It can be useful to break a landscape into discrete ecosystems with clear boundaries for the purposes of analysis (see chap. 4), but landscape ecology recognizes that ecosystems are in fact open systems. What flows into an ecosystem can be as important in determining the qualities of that ecosystem as what takes place within its boundaries. No single entity can be understood without considering its relationship to what is nearby. Furthermore, the spatial pattern in which those entities are arranged is important to how a landscape works.