If we are to protect this irreplaceable biological diversity, we must reduce fragmentation and restore the health and vitality of our forest communities. Increasing emphasis is being placed on the management needs of non-game species including rare, threatened and endangered species and their habitats. As habitat declines, the number of animals capable to inhabit these areas declines. Both of these forest types are very susceptible to the negative effect of habitat edges. In addition small forest tracts cause reductions in effective population sizes.
Population size is the predictor of extinction probability.
Also, the disjunction of forest patches inhibits the movement between isolated habitats. This resulting genetic isolation can be detrimental to the long-term health of resident populations due to inbreeding. Inbreeding erodes genetic variability, and eventually, the viability of a given population. The variety, frequency, distribution, and health of Illinois' wildlife depends directly on the size, species, and distribution of forest tracts. Functional ecosystems are dependent upon the contiquity and connectivity of forest tracts.