GC13K-03
Getting to the root of the matter: Landscape implications of plant-fungal interactions for tree migration in Alaska
Monday, 14 December 2015: 14:10
3003 (Moscone West)
Rebecca E Hewitt1, Alec Bennett2, Amy Lynn Breen2, Teresa N Hollingsworth3, Donald Lee Taylor4, Terry Chapin5 and Scott T Rupp2, (1)Northern Arizona University, Center for Ecosystem Science and Society, Flagstaff, AZ, United States, (2)University of Alaska Fairbanks, Scenarios Network for Alaska & Arctic Planning, Fairbanks, AK, United States, (3)University of Alaska Fairbanks, Fairbanks, AK, United States, (4)University of New Mexico, Department of Biology, Albuquerque, NM, United States, (5)University of Alaska Fairbanks, Institute of Arctic Biology, Fairbanks, AK, United States
Abstract:
Forecasting change in forest cover across Alaska tundra is critical to predicting regional ecosystem services, including climate feedbacks such as carbon storage. Controls over seedling establishment govern forest development and migration potential. Ectomycorrhizal fungi (EMF), obligate symbionts of all Alaskan tree species, are particularly important to seedling establishment, yet their significance to landscape vegetation change is largely unknown. We used ALFRESCO, a landscape model of wildfire and vegetation dynamics, to explore whether EMF inoculum potential influences patterns of tundra afforestation and associated flammability. Using two downscaled CMIP3 General Circulation Models (ECHAM5 and CCCMA) and a mid-range emissions scenario (A1B) at a 1 km2 resolution, we compared simulated tundra afforestation rates and flammability from four parameterizations of EMF effects on seedling establishment and growth from 2000-2100. Modeling predicted an 8.8-18.2% increase in forest cover from 2000 to 2100. Simulations that explicitly represented landscape variability in EMF inoculum potential showed up to a 2.8% reduction in afforestation due to low inoculum potential limiting seedling growth. This reduction limited fuel availability and thus, cumulative area burned. Regardless of inclusion of EMF effects in simulations, landscape flammability was lower for simulations driven by the wetter and cooler CCCMA model than the warmer and drier ECHAM5 model, while tundra conversion to forest was greater. Results suggest abiotic factors are the primary driver of tree migration. Simulations including EMF effects, a biotic factor, yielded more conservative estimates of landcover change across Alaska that better-matched empirical estimates from the previous century.
