Forest fragmentation, or habitat fragmentation, is the breakdown of habitat from a large, contiguous swath into smaller, distinct, discontinuous pieces. When habitat is broken apart three interrelated processes occur 1) reduction of the total amount of vegetation, in other words, habitat loss, 2) division of remaining vegetation into remnants or patches and 3) new land-use types are introduced which replace lost vegetation. The fracturing of forested habitat creates an island type biogeography, in which the biodiversity of the island is directly related to the size and isolation of that island, a similar phenomenon is observed within fragmented habitats.
The most common reasons for habitat fragmentation in U.S. are the construction of infrastructure, agriculture, utility corridors and other human developments. The incremental pace of damage makes visualization of the big picture problem difficult, but over time the non-forest patches expand and grow, disconnecting forested land and scattering habitat. This is a serious threat to the health and function of the ecosystem. The effects of habitat fragmentation are well-studied and documented worldwide, the results are the reduction and subsequent loss of biodiversity, increase of invasive species and pests, lowered resistance to pathogens and reduction in water quality.
In addition to the isolation created between forest communities, habitat fragmentation also produces “edge effects”, which alter the growing conditions within the forest by changing the temperature, light penetration, air-flow and moisture levels. This causes cascading damage to vegetation and wildlife health, growth, survivability and resilience. Habitat fragmentation reduces true interior forest conditions; where conditions remain cool, damp and shady, where the noises of society and industry cannot be heard; these conditions are only found 200-300 feet from a forest edge. This means that a fragment of habitat needs to be a minimum of 14 acres in diameter in order to create just 1 acre of these ideal conditions.
Forestry practices become increasingly difficult when conditions are impaired, normal operating procedures are impractical, become fiscally inefficient and culturally deplorable. Additionally, the value added to our communities and economies is diminished by these losses; all of which contributes further to fragmentation and permanent losses. In heavily forested areas, common to the northeast, the effects of forest fragmentation seem less dramatic as we are still left with plenty of room for hiking, hunting, skiing and working, but the non-contiguous nature of these forests is still problematic for vegetation and wildlife. When the detriment is not immediately apparent it is harder to find and keep support for protective or conservation measures, but timing is essential, preservation of continuous forest is as beneficial to human populations as it is to wildlife.