UPLAND FOREST: Background

Upland forests within the mid-Atlantic Coastal Plain are generally considered a mixture of pine and hardwood species. The relative contribution of these forest components shifts from the coast to the fall line such that pine-dominated forests are primarily on the outer Coastal Plain and hardwood-dominated forests are primarily on the inner Coastal Plain. However, this natural gradient has been highly modified by the conversion of hardwoods to pine plantations and the suppression of fire within the outer Coastal Plain.

Currently, upland forests are widely distributed throughout the physiographic region. However, different patterns of landuse have altered these forests in different ways and to different extents. Within the southern portion of the physiographic region, uplands are primarily owned by the wood products industry and have been converted to intensively managed pine monocultures. Pine-dominated forests within the Delmarva Peninsula and along the lower western shore of the Chesapeake Bay have been highly fragmented and dissected for over 200 years within these agriculturally dominated landscapes. Expansion and coalescence of the urban centers along the fall line (Baltimore, Washington, D.C., Fredericksburg, Richmond, and Petersburg) has resulted in the fragmentation and degradation of critical hardwood-dominated forests. The significant blocks of hardwood-dominated forest that remain have become increasingly isolated within an urbanized landscape. Similar patterns now occur for pine-dominated forests within urban centers on the coasts of all 4 states within the region.

One factor that has an influence on the use of forests by priority species is forest composition. Within coastal Virginia, incidence rates and breeding densities of several priority species changed with forest composition. For the majority of these species, both of these indicators were positively related to the degree of domination by hardwoods at the stand level. This pattern along with the geographic distribution of hardwood-dominated forests suggests that upland forests within the inner Coastal Plain may hold high conservation significance for many of these species. Continued conversion of these forests to pine plantations may be detrimental to priority species.

A second factor that has an influence on the use of forests by priority species is vegetational structure. Both the vertical and horizontal complexity of vegetation have been shown repeatedly within many geographic areas to influence breeding bird diversity. However, because species utilize vegetational components in different ways, management practices that promote particular components of the vegetation will almost invariably benefit some species to the detriment of others. Even so, some changes in vegetation structure may be detrimental to a large portion of the bird community. Overpopulation of the white-tailed deer herd often leads to destruction of understory vegetation required by many priority species. This problem is particularly evident around the periphery of urban areas along the fall line and within the agricultural landscapes of the Delmarva Peninsula. Closed canopy forest management practices may also eliminate understory vegetation.

A third factor that has an influence on the use of forests by birds is patch size. Several of the priority species that utilize forests within the mid-Atlantic Coastal Plain appear to require forest patches of a particular size to successfully reproduce. Forest fragmentation has rendered many areas unsuitable for these species. Fragmentation is of particular concern within the inner Coastal Plain because urbanization will likely have an irreversible impact on important hardwood-dominated forests.