Landscape and Wildlife Conservation

Research on Wildlife-Landscape Interactions

Ecologists have studied wildlife ecology and habitat use for decades. Before the 1970s, most studies of wildlife ecology were not spatially explicit but simply categorized wildlife observations by habitat type, not location. This approach reflected the traditional emphasis in biological ecology on evolutionary processes rather than on spatiotemporal patterns. However, beginning in the late 1960s, theoretical and technological developments helped increase attention to the relationships between process and pattern. First, the theory of island biogeography, published in 1967 by the biologists Robert MacArthur and E. O. Wilson, proposed that an island's size and proximity to other landmasses was a robust predictor of the number of species in, and other characteristics of, the island's biota. Subsequently, other researchers showed that habitats that are not islands but occur in scattered, discrete patches—such as areas of alpine tundra surrounded by montane forest—are analogous to islands in how their size and spatial arrangement affect the distribution of species across landscapes. Second, in the 1980s, the field of landscape ecology flourished with the development of patch mosaic theory, which posits that landscapes consist of a variegated pattern (or mosaic) of areas (or habitat patches) having distinct environmental conditions. Landscapes change because conditions in [Page 1697]the habitat patches fluctuate through time, a process called patch dynamics. Finally, during the 1990s, the development and increased availability of geographic information system (GIS) software and the global positioning system (GPS) decreased the cost and increased the feasibility of spatially explicit wildlife research.

Also, since the 1970s, studies of wildlife-landscape interaction have become more prominent due to a growing concern with human-caused environmental change. Organisms respond to environmental change—whether cyclic, long term, or rapid—by migrating from habitat patches where conditions have become unsuitable to those where conditions remain, or have become, suitable. Researchers can develop conservation strategies by analyzing habitat spatiality and patch dynamics, including human disturbance, with regard to the behavior and physiology of particular species.

Wildlife species vary enormously in terms of behavior and physiology, but five factors are important in determining how patch dynamics affect a particular species. First, an animal's size is a basic determinant of habitat requirements; larger animals need larger habitat patches. Second, animals vary in the specificity of their habitat requirements, between specialists that can tolerate only the range of environmental conditions in a specific habitat type and generalists that can tolerate environmental conditions in a broad range of habitats. Habitat specificity greatly influences a species’ ability to move between patches. For instance, deforestation in the Amazon often isolates birds in remnant forest patches because they are unable to cross even narrow clearings. Third, animals vary in mobility between sedentary and vagile (ability to move long distances). Fourth, animals vary in territoriality, between those that aggressively defend a particular area from other individuals of the same species and those that do not. If the habitat patch occupied by an individual in a highly territorial species becomes unsuitable, the animal may perish if nearby, suitable patches are already occupied. Finally, every species is unique ecologically, so that specific patch dynamics in a particular time and place may differently affect similar species. For example, gorillas and chimpanzees in Gabon's rain forests respond differently to human disturbance because human activities produce patches of plants that gorillas eat but decrease the abundance of chimpanzee food plants. While these behavioral and physiological factors may be correlated—for instance, many generalists are highly vagile—they are distinct and must be considered individually.

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