There is no set size, shape, nor boundary. The Global Biodiversity Assessment, published the United Nations Environment Programme, explicitly cites the Wildlands Project authored by Dr. Reed Noss, as central to the protection of biodiversity as required by Article 8 of the Convention of Biological Diversity. Dr. Noss call for at least half of the lower 48 states to be restored to core wilderness areas, which are connected by corridors of wilderness. Noss says this should be enough providing that most of the remaining land is managed for conservation objectives. The buffer zones which surround the wilderness areas are designed to be managed for conservation objectives with limited human activity.
Transition zones are the areas in which sustainable communities are to be developed.
Within each bioregion, dozens, even hundreds of individual projects may be underway simultaneously, all having some relavance to the ultimate construction of the bioregion. Two primary components of bioregions are Biosphere Reserves, and rivers and streams protected by the Wild and Scenic Rivers Act, or the River Heritage program. Rivers and streams are being used to form the corridors that connect the core wilderness areas. Biosphere Reserves are important because 47 such reserves already exist and are committed to bioregional management by virtue of the voluntary agreement implied by the UN designation. Biosphere Reserves are described as the laboratories fro learning how to create and implement bioregional management.