PARENT SESSION
Oral Session #6: Disturbance Ecology of Forests: Fire, Patterns. Presiding: R. DeFries.
Monday, August 6, 2001. 8:00 AM to 12:00 PM. Hall of Ideas F.

Effects of altered disturbance in plant communities: Fire suppression in a mixed-conifer forest, montane grassland and oak savanna.

Wolf, Joy¹, ¹

ABSTRACT- Natural disturbance regimes are key elements of vegetation patterns and dynamics, and maintain heterogeneity in natural plant communities. Typically, natural disturbance, such as fire, facilitates native species establishment and maintains species diversity; however, fire suppression can alter disturbance frequency, forest structure and native species richness. Whereas plant species in mixed-conifer forests, montane grasslands and oak savannas are adapted to fire disturbance, these communities experienced over a century of fire suppression. In this study, I illustrate the effect of fire suppression on three types of plant communities that exist within protected boundaries. To determine the effect of fire suppression on native species richness, my methodology included dendrochronology techniques to quantify the fire history and age structure, and paired plot analysis to determine species composition. The results show that fire suppression decreased the fire frequency in a mixed-conifer forest, increased exotic species while decreased native species in a montane grassland, and modified the age structure in an oak savanna grove. These results contribute toward understanding the variety of effects that altered disturbance regimes can have in the structure, function, and composition of native plant communities. A future implication of altered fire disturbance is the spread of ecologically invasive and non-native species. This work assists land managers in decision-making of restoration efforts, particularly in the re-introduction of fire disturbance into certain ecosystems.

KEY WORDS: disturbance ecology, fire suppression, natural areas