PARENT SESSION
Symposium #14: Fire and invasive plant ecology and management: the need for integration to effectively restore ecosystems.

Organized by: M Brooks and M Pellant
Tuesday, August 6. 1:00 PM to 4:30 PM. Turquoise Ballroom, TCC.

Impacts of invasive alien plants on fire regimes.

RICHARDSON, DAVID^*,1, RUNDEL, PHILIP¹, VAN WILGEN, BRIAN¹, ¹ Institute for Plant Conservation, Botany Department, Rondebosch 7701, Western Cape, SOUTH AFRICA

ABSTRACT- Components of the fire regime include the fire-return interval, size/pattern and intensity of fire over long periods of time, and the immediate effects of fire. These elements are determined by many physical and biotic factors. In many parts of the world, alien plants (those introduced through human activity) have spread from sites of introduction. Such invasions add new components to plant communities, sometime eliminating native components in the process. Such changes have the potential to alter the fire regime in many ways, e.g., by increasing fuel loads, changing the distribution of fuel types in the community profile. This paper provides a theoretical framework for considering the potential changes in fire regime due to plant invasions. Our focus is on alien plant invasions at the scale of decades, but range expansions and natural migrations over longer time scales (centuries, millennia) are also discussed. Important links with other agents of change, most notably grazing, are discussed. We then consider invasions that have caused different types of changes in fire regimes. Examples include grass invasions in Hawaii, Californian coastal sage and North American deserts; and tree and shrub invasions in South African fynbos and southern Florida. Finally, we attempt to predict what further changes may occur in the future with additional invasions and global change.

KEY WORDS: biological invasions, ecosystem-level impacts, fire