Protected Area

The design of protected areas is an important field of research in conservation biology. The essential questions involve criteria for the size, shape, and positioning of protected areas to optimize their ability to protect biodiversity, while using funding as efficiently as possible. Conservation biologists recommend that protected areas be as large and numerous as possible. Other design aspects, however, are more controversial. Controversy over the design of protected areas involves the following key elements:

• Is it preferable to have one large reserve, or a number of smaller ones of the same total area? Conservation biologists identify this question with the acronym SLOSS, which stands for: single large, or several small. According to ecological theory, populations in larger protected areas should have a smaller risk of extinction, compared to those in smaller reserves. However, if there are populations in several different reserves, the redundancy might prevent extinction in the event of a catastrophic loss in one reserve.
• Reserves can also be designed to have less edge (or ecotone) habitat. This refers to transitions between ecosystem types, such as that between a forest and a field. Edge habitat is often penetrated by invasive species and predators, which can become important problems in some protected areas. In addition, many species require interior habitat for breeding; meaning they are intolerant of ecotones. Larger protected areas have proportionately more interior habitat, as do simple-shaped ones (a circle has the smallest ratio of edge to area).
• For many ecological functions to operate well, there must be connections among habitats. This is particularly true of the dispersal of plants and animals. This need can be accommodated if protected areas are linked by corridors of suitable habitat, or if they are clumped close together. However, corridors might also serve as conduits for invasive species and diseases.