FRONTIER FORESTS World Resources Institute (Bryant, D. et al. 1997)
Frontier forests are the world's remaining large intact natural forest ecosystems. These forests are -- on the whole -- relatively undisturbed and big enough to maintain all of their biodiversity, including viable populations of the wide-ranging species associated with each forest type. As defined in this assessment, a frontier forest must meet seven criteria:
It is primarily forested.
It is big enough to support viable populations of all indigenous species associated with that forest type -- measured by the forest's ability to support wide-ranging animal species (such as elephants, harpy eagles, or brown bears).
It is large enough to keep these species' populations viable even in the face of the natural disasters -- such as hurricanes, fires, and pest or disease outbreaks -- that might occur there in a century.
Its structure and composition are determined mainly by natural events, though limited human disturbance by traditional activities of the sort that have shaped forests for thousands of years
such as low-density shifting cultivation -- is acceptable. As such, it remains relatively unmanaged by humans, and natural disturbances (such as fire) are permitted to shape much of the forest.
In forests where patches of trees of different ages would naturally occur, the landscape exhibits this type of heterogeneity.
It is dominated by indigenous tree species.
It is home to most, if not all, of the other plant and animal species that typically live in this
type of forest.