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Plant toxins and trophic cascades alter fire regime and succession on a boral forest landscape

October 1, 2012

Two models were integrated in order to study the effect of plant toxicity and a trophic cascade on forest succession and fire patterns across a boreal landscape in central Alaska. One of the models, ALFRESCO, is a cellular automata model that stochastically simulates transitions from spruce dominated 1 km2 spatial cells to deciduous woody vegetation based on stochastic fires, and from deciduous woody vegetation to spruce based on age of the cell with some stochastic variation. The other model, the ‘toxin-dependent functional response’ model (TDFRM) simulates woody vegetation types with different levels of toxicity, an herbivore browser (moose) that can forage selectively on these types, and a carnivore (wolf) that preys on the herbivore. Here we replace the simple succession rules in each ALFRESCO cell by plant–herbivore–carnivore dynamics from TDFRM. The central hypothesis tested in the integrated model is that the herbivore, by feeding selectively on low-toxicity deciduous woody vegetation, speeds succession towards high-toxicity evergreens, like spruce. Wolves, by keeping moose populations down, can help slow the succession. Our results confirmed this hypothesis for the model calibrated to the Tanana floodplain of Alaska. We used the model to estimate the effects of different levels of wolf control. Simulations indicated that management reductions in wolf densities could reduce the mean time to transition from deciduous to spruce by more than 15 years, thereby increasing landscape flammability. The integrated model can be useful in estimating ecosystem impacts of wolf control and moose harvesting in central Alaska.

Publication Year 2012
Title Plant toxins and trophic cascades alter fire regime and succession on a boral forest landscape
DOI 10.1016/j.ecolmodel.2012.06.022
Authors Zhilan Feng, Jorge A. Alfaro-Murillo, Donald L. DeAngelis, Jennifer Schmidt, Matthew Barga, Yiqiang Zheng, Muhammad Hanis B. Ahmad Tamrin, Mark Olson, Tim Glaser, Knut Kielland, F. Stuart Chapin, John Bryant
Publication Type Article
Publication Subtype Journal Article
Series Title Ecological Modelling
Index ID 70047908
Record Source USGS Publications Warehouse
USGS Organization Southeast Ecological Science Center