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Scheller Abstract for US-Int'l Assoc. Landscape Ecology Conference

posted Mar 20, 2012, 4:24 PM by   [ updated Mar 20, 2012, 6:41 PM ]

Using stochastic simulation to evaluate competing risks of wildfires and fuels management on an isolated forest carnivore

Robert M. Scheller1, Wayne D. Spencer2, Heather Rustigian-Romsos2, Alexandra D. Syphard2, Brendan C. Ward2, James R. Strittholt2

In the Sierra Nevada of California, proposals to thin vegetation to reduce wildfire risks have been controversial because fuel treatments could adversely affect fisher (Martes pennanti) populations.  Vegetation thinning reduces fisher habitat value. Conversely, crown-replacing wildfires also threaten fisher habitat over much broader areas than fuel treatments.  We coupled three spatial models to simulate the effects of wildfires and fuels management on fisher habitat and population size: a forest succession and disturbance model, a fisher habitat model, and a fisher metapopulation model. We varied fuel treatment rate, treatment intensity, and fire regime, and assessed their relative effects on simulated fisher population size.  We compared the immediate negative effects of fuel treatments to the longer-term positive effect of fuel treatment using structural equation modeling.  Our results indicate that the direct, negative effects of fuel treatments on fisher populations are generally smaller than the indirect, positive effects of fuel treatments, because fuels treatments reduced the probability of large wildfires.  These benefits of fuel treatments varied by elevation, treatment location, and fire regime.  However, there was large uncertainty in our projections due to stochastic wildfires and fisher populations, demonstrating the difficulty of projecting future populations in systems characterized by large, infrequent, stochastic disturbances.