Isolation also prevents dispersal of organisms away from their birth sites. This is often needed to prevent inbreeding which causes loss of genetic diversity. Many animals cannot or will not cross through different habitats to find new, suitable habitats. Southern flying squirrels for example will not cross agricultural fields. Some songbirds such as the Blue-gray Gnatcatcher, have territorial boundaries that coincide with habitat boundaries.
Isolation is also a problem for pollination of plants.
Many require insect pollinators which are not able to find the small isolated pockets of plants. Unable to get pollen from other plants, self-pollination will occur leading to inbreeding. Studies have shown that plants in fragmented habitats are visited left often by pollinators and have fewer seeds and hence lower reproduction. This inability to find the plant also is detrimental to the pollinator as they often require specific plants on which to feed. Finally, as a woodlot gets smaller its edge to interior area ratio increases.