PARENT SESSION
Oral Session # 40: Fire Ecology II: Forests.
Presiding: D Falk
Wednesday, August 6. 8:00 AM to 11:30 AM, SITCC Meeting Room 102.
The influence of climatically altered fire regimes on successional patterns across the Yellowstone landscape.
Schoennagel, Tania *,1, Turner, Monica2, Fall, Andrew3, Kashian, Daniel 4, 1 University of Colorado-Boulder, Boulder, CO2 University of Wisconsin-Madison, Madison, WI3 Simon Fraser University, Vancouver, BC, Canada4 Colorado State University, Fort Collins, CO
ABSTRACT- Fire regimes throughout the Rocky Mountains are expected to vary with climate change over the next century, yet landscape consequences of possible shifts in fire regimes remain unknown. We created a spatially explicit probabilistic model using SELES to examine how variation in climate will affect the fire regime and consequently the age and density of lodgepole pine stands across a c. 500,000-ha landscape of Yellowstone National Park. Based on a 2 x CO2 climate change scenario for the region, fire regimes are expected to reduce mean stand age from 250 to 200 yrs. This decline in mean age was not associated with significant change in mean stand density across the landscape. Stand densities remained relatively unchanged as significant self-thinning by lodgepole pine occurs predominantly in stands < 100 yrs old, after which densities remain relatively constant over time. However, the introduction of spatial variation in ignition probabilities influenced the response of stand densities to altered fire regimes. When low-elevation, highly serotinous stands preferentially burned, stand densities across the landscape increased and were more variable relative to high-elevation stands where serotiny is low. Although adaptive responses to fire frequencies are not represented in our model, serotiny may increase at higher elevations with more frequent fire, resulting in denser stands across the landscape. In response to climate change scenarios considered for this region, the age structure of the landscape is expected to become younger, yet stand structure appears to be much more resilient to wide variation in fire regimes.
Key words: Yelowstone National Park, Pinus contorta, climate change, fire ecology