Principios ecologia da paisagem

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Principles of Landscape Ecology
By: William R. Clark (Department of Ecology, Evolution, and Organismal Biology, Iowa State University) © 2010 Nature Education 

Citation: Clark, W. (2010) Principles of Landscape Ecology. Nature Education Knowledge 2(2):34

Landscape ecology is the study of the pattern and interaction between ecosystems within a region of interest, and the way theinteractions affect ecological processes, especially the unique effects of spatial heterogeneity on these interactions



Historical Perspective

Throughout the history of ecology, scientists have observed variability across time and space in the abiotic and biotic components of ecosystems. But early ecologists did not have the technology or concepts to explicitly deal with spatial heterogeneity, sothere was a tendency to develop explanations by grouping organisms into uniform and recognizable units. For example, scientists were struck by the relatively consistent associations of plant species and grouped vegetation into community types (Mueller-Dombois & Ellenberg 1974). Compared to vegetation, where observed change was rather slow, observations of fluctuating populations ranging frombacteria and protozoans in the laboratory to snowshoe hares (Lepus americanus) in the boreal forest, led scientists to mathematical theories that explicitly focused on temporal dynamics (Kingsland 1995). But the resulting models treated the environment as spatially homogeneous. Such views of nature and the theory about dynamics led to “equilibrium” concepts (May 1973) that dominated ecological thinkingfrom the 1920s through the 1980s.

During the 1980s, advances in the accessibility of computing, remotely sensed satellite and aerial imagery, development of geographic information systems (GIS, ARC/INFO was first released in 1982), and spatial statistical methods (Fortin & Dale 2005), enabled ecologists to observe and analyze spatial heterogeneity ranging from local habitats to entirecontinents. The technology enhanced a paradigm shift occurring in ecology and the emergence of landscape ecology as a sub-discipline within ecology (Wu & Loucks 1995). Landscape ecology specifically recognizes that disturbance, whether anthropogenic or caused by natural processes, creates spatial heterogeneity that is the normal condition of ecosystems. In landscape ecology particularly, a “non-equilibrium”view emerged, that links disturbance in time and space to system structure and function in feedback loops that influence the ecology and evolutionary trajectories in the ecosystems. The International Association of Landscape Ecology was formed in 1982. In 1986, Forman and Godron published their seminal text on landscape ecology. This work was important, not only because it outlined principles,but also because it brought together the North American scientific interest — typically focused on heterogeneity in ecosystems — with more anthropocentric scientific traditions of geography, landscape architecture, and planning, rooted in the long history of landscape alteration in Europe.


Terminology and Concepts

Imaging and mapping technology naturally promoted a patch-corridor-matrixapproach to landscape ecology. Examining the map of an area in North Dakota (Figure 1) helps to define important vocabulary and illustrates some typical questions studied by landscape ecologists. A patch is an area of habitat differing from its surroundings, often the smallest ecologically distinct landscape feature in a landscape mapping and classification system. In Figure 1, wetlands and perennialgrasslands would likely be patches of focal interest for the study of ecological processes. The matrix is the majority of the surrounding landscape (i.e., not the patches); in this case the matrix primarily consists of fields of agricultural crops. The large proportion of the landscape classified as matrix may have profound influences on the ecological processes in the landscape; for example,...
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