Category: Ecological Research
Title: Fire Effects on Gambel Oak in Southwestern Ponderosa Pine-Oak Forests
Author: * Abella, S.R., * Fule, P.Z.
Subject: Gambel Oak (Quercus gambelii), Ponderosa pine (Pinus ponderosa), Fire effects, Reference conditions
Abstract: Gambel oak (Quercus gambelii) is ecologically and aesthetically valuable in southwestern ponderosa pine (Pinus ponderosa) forests. Fire effects on Gambel oak are important because fire may be used in pine-oak forests to manage oak directly or to accomplish other management objectives. We used published literature to: (1) ascertain historical fire regimes in pine-oak forests, (2) discern prescribed burning effects on Gambel oak survival and diameter growth, and (3) provide suggestions for using fire to manage oak. Frequent fire is part of Gambel oaks historical environment, as historical fire return intervals often averaged less than 10 years in pine-oak forests. More than 66 percent of oaks greater than 6 inches (15 cm) in diameter were alive at least 5 years after two contemporary prescribed fires, whereas survival was low (20 percent) for small oaks less than 2 inches (5 cm) in diameter. Top-killed oaks resprout prolifically, suggesting that fire can maintain shrub-sprout forms of oak constituting browse and cover for some wildlife species. Unlike mechanically thinning competing trees, burning has not been found to increase oak diameter growth. We conclude that fire can be used to manage Gambel oak densities and growth forms, and that large oaks can be maintained during low-intensity burning. Several tactics may enhance survival of large oaks during prescribed fire: keeping pine slash away from oak boles, avoiding lighting near oaks or reducing fire intensity near oaks, and raking fuels away from oak boles.
Source: Rocky Mountain Research Station
Publisher: USDA Forest Service, Rocky Mountain Research