Prescribed Fire and Its Effects on Forested Ecosystems

Since 1989, scientists at Coweeta Hydrologic Laboratory and collaborators have investigated the impacts of prescribed burning with long-term, interdisciplinary, ecosystem approaches. Studies have examined ecosystem processes such as net primary production, nutrient and carbon cycling, and vegetation dynamics (regeneration, compositional changes, mortality, diversity) in a number of forest types and fire prescriptions (Vose et al. 1993, 1996, 1997, 1999, 2005; Vose 1994, 2000, 2003).

Coweeta's research approach uses watershed-scale (water quality and quantity) and within watershed scale (plot level changes in nutrient and carbon cycling, vegetation dynamics) assessment of ecosystem responses to prescribed fire. The watershed approach facilitates extrapolation of small-scale disturbances to larger landscape units. One unique aspect that has been addressed is the long- and short-term impacts of prescribed fire on ecosystem sustainability, using rates and pool sizes of carbon, nutrients, and water as key indicators of sustainability.

Prescribed burning in southern Appalachian ecosystems has many potential benefits:

1. reduction of fuel loads to minimize the risk and impacts of wildfire;
2. reduction of the evergreen understory to promote regeneration of desirable species such as oaks and hickories;
3. increased diversity of plants, small mammals, birds, amphibians, and insects;
4. stimulation of fast-growing new shoots to increase productivity;
5. stimulation of nutrient cycling rates to increase site productivity; and
6. restoration of degraded ecosystems.

After nearly a century of exclusion, re-introduction of fire into the current forests of the southern Appalachians will have varying effects on ecosystem properties and vegetation structure and composition depending on fire type (intensity, severity, frequency, timing, and scale) and forest type (current species composition and structure, slope, soils, microclimate, and fuel load). Therefore, there is a need for thorough investigation of the effects of prescribed fire on ecosystem processes in multiple forest types; and knowledge is needed on the interactions between historical fire regimes, current ecosystem structure and function, and ecosystem responses to prescribed fire. To date, Coweeta scientists and partners have evaluated ecosystem responses to fire in xeric, low productivity pitch pine (P. rigida)/mixed hardwood forests; dry, moderate productivity shortleaf pine (P. echinata)/oak forests; mesic, high productivity, mixed hardwood (L. tulipifera/Q. rubra) forests; and Piedmont and Coastal Plain high productivity, pine forests.