Hard edges are rare in nature, yet we have often expected to create sharp transitions between protected areas and those where resources are extracted for human use. In practice, Core Reserves suffer greatly from extractive activities on their borders, and lose substantial amounts of their effective area.
The edge of Tilden Park provides a buffer between wildfire-prone open spaces and the hillside homes of Kensington, Berkeley, and Oakland.
The results of human activity often reach beyond the site where they occur. For instance, the freshly exposed expanse of a clear-cut leaves the adjoining trees vulnerable to being toppled by the wind. It allows extremes of heat and cold to penetrate into the forest, along with predatory species that hunt the species of the deep woods.
When Core Reserves occur right next to large clear-cuts or working mines, they become functionally much smaller than their apparent boundaries. In these cases, invasive species such as magpies and opossums range into the reserves, diminishing their effective size. Other impacts can include toxic contamination and habitat fragmentation.
These impacts can be avoided by cushioning the edges of the core reserves with buffer zones where human activity is limited in scope and impact. These areas serve the same function as a foyer, in which people remove their wet and muddy outer-garments before entering the rest of the house. Road densities are kept low to discourage incursion of poachers and others who would violate the protections established for the reserve. Buffers also reduce conflicts between humans and large predators such as grizzly bears. Designed properly, Buffers can serve as extensions core reserves and Wildlife Corridors.
As with the core reserves, these areas are managed to satisfy the needs of wildlife and ecosystems. To enhance their value, the buffer zones themselves can be zoned with increasingly restrictive land-uses as the core reserve is approached. Drive-up camping might be allowed in the outer ring, while recreation in the inner zone could be restricted to primitive camping and low-impact pursuits such as hiking, bird-watching, or cross-country skiing. Forestry and fishing would likewise be more restrictive nearer the core reserve. Traditional cultural uses and Ecotourism are compatible uses throughout a buffer zone.
Around areas that are protected for their conservation values, establish buffer zones where products can be extracted from the wild, subject to limitations that ensure the continued ecological integrity of core and buffer areas alike.