Fire Ecology of Pitch and Virginia Pine

Fire has played a major role in the dominance of pitch (Pinus rigida) and Virginia pines (Pinus virginiana).  These pines, which typically dominate south- and west facing slopes in the Southern Appalachians, make up major components of the xeric-oak pine and pine heath communities of this region.  Both pines characteristically grow on poor sites, with generally sandy, gravelly, or shallow soils. 

Silvical characteristics of pitch pine suggest it is well adapted to fire. It has thick bark and the ability to refoliate from dormant buds located along the stem and branches, or from the basal crook located just below ground line (Little 1979). Moreover, a majority of the trees have serotinous cones especially where fires are severe (Little 1974).  Seed is also produced at an early age, 3 to 4 years for sprouts and 10 years for seedlings (Little 1953).  Due to its thin bark, Virginia pine is less tolerant of fire than pitch pine, although basal sprouting and seed production at a young age does offer this species degree of fire tolerance.

Historically, mixed severity fires were probably prevalent over much of the range of pitch and Virginia pines. Native American burning maintained pitch pine using an understory fire regime type, with a 2- to 10-year return interval (Wade and others 2000). This frequency maintained stands with relatively large pines, scattered smaller pines and oaks, and sparse understory of low ericaceous shrubs and herbs (Little 1946, 1973). Due to its higher tolerance to fire, the importance of pitch pine in stands likely increased relative to Virginia pine with increasing fire frequency.  Although the historical fire regime in Virginia pine is unknown, it was likely less frequent and resulted in higher mortality than that of pitch pine.

Today, altered fire regimes have increased fire return intervals in the xeric-oak pine and pine heath communities where pitch and Virginia pine occur. In the absence of fire, these yellow pines are usually outcompeted by hardwood species or eastern white pine. On upland sites, trees usually invade much faster than understory shrubs such as huckleberries and blueberries (Little 1979; Little and Moore 1949). On more mesic sites, fire exclusion leads to replacement by red maple, blackgum, sweetbay, American holly, and dense shrub understories (Little 1979).

In order to restore community composition of these oak-pine forests in the Southern Appalachians, the use of prescribed fire has been advocated by federal and state agencies (Swift and others 1993; Vose and others 1994, 1997). Due to the hazards of using fire in steep topography and the susceptibility of these soils to erosion, the use of prescribed fire in this area is rare relative to its use in the coastal plain. Consequently, little information is available on the appropriate frequency, intensity and season fires should be prescribed for ecological restoration; comparably more information is available on the silvicultural uses of fire in pitch and Virginia pine.