April 26, 2006
Fire As An Ecosystem Process: Past, Present and Future
This year's William P. Thompson Memorial Lecture will be given by Jon Keeley, a distinguished USGS research scientist and adjunct faculty at UCLA. This event will occur next Wednesday, May 3 at 4:00 pm in Room 17 in the Forestry Building.
The abstract of his seminar on fire in ecosystems is below.
Please join us either before the seminar for refreshments at 3:30, or after the seminar for further refreshments at Flagstaff Brewing Company.
Fire As An Ecosystem Process: Past, Present and Future
Jon E. Keeley
A global view of potential vs actual vegetation distribution points to fire as a major driver of ecosystem distribution, and determinant of community structure. Fire acts much like an herbivore, consuming biomass and competing with biotic consumers for resources. Fossil evidence is clear that as an ecosystem phenomenon, fire dates at least to the Mesozoic over 100 mya. However, these records do not necessarily demonstrate fire was an important ecosystem process. Global climate changes leading to marked seasonality were required, and the first widespread evidence of seasonality is from the late Tertiary. Massive C4 grassland expansion between 4-7 mya may be the first example of the extensive influence of fire in shaping global ecosystems. The ecosystem fire triangle requires coupling primary productivity, seasonality and ignitions. However, in order to understand fire effects one must view this within the context of gradients in productivity and ignitions, which dictate different fire regimes. California provides a useful model as there are marked geographical gradients in fuel production and ignition potential. One can recognize very different fire regimes ranging from frequent low intensity surface fires to high intensity crown fires. These regimes have selected for very different life histories in associated plant communities. These life histories lead to very different patterns of community resilience to landscape patterns of high intensity crown fire. Translating the ecosystem fire triangle to fire management requires including a fourth dimension of weather and climate. Cost/benefit analysis of fuel treatments requires attention to regional patterns in both fire regimes and predictability of extreme fire weather. Future climate predictions necessitates an understanding of the functional
differences between ecosystems in the impact of antecedant climate on different fuel layers and interactions with extreme weather events.
Jon Keeley's website is http://www.werc.usgs.gov/seki/keeley.asp