PARENT SESSION
Organized Oral Session 5: Biome and Coastal Models for Local Sites and Biosphere Regions
Organized by: JS Olson and D Ojima
Friday, August 8. 9:00 AM to 12:00 PM, SITCC Meeting Room 106.
Simulation of Carbon Dynamics and Fire Regimes in Boreal Forests of Eurasia and North America.
Ito, Akihiko*,1, Post, Wilfred2, Alexandrov, George3, 1 Frontier Research System for Global Change, Yokohama, Kanagawa, Japan2 Environmental Sciences Division, Oak Ridge, Tennessee3 Center for Global Environmental Research, Tsukuba, Ibaraki, Japan
ABSTRACT- Conifer forests' increased exploitation and climatic change make modeling structure and function increasingly important. Sim-CYCLE's five carbon pools and 16 fluxes simulate production, allocation, and decomposition ecophysiologically. Simulations of boreal forests in Russia and Alaska now include burning. Fire frequency, severity, and extent are simulated with a cellular automaton for 100 km2 (200 rows and 200 columns). East Siberian (62N, 119E) larch, a deciduous conifer, compares with evergreen conifers, e.g. spruce, near Fairbanks (65N, 147W). Wildfires increase heterogeneity of carbon budgets. Siberian fire recurrence interval averages 50 years, restricting carbon storage, despite slow decomposition. The cellular automaton simulates spatial heterogeneity in landscapes. Over 600 years, wildfire can reduce regional C-storage by 20%. But prescribed fire suppression may not increase storage, because fire severity increases with fuel accumulation. Spatial heterogeneity (sub-grid scale for global models) should be included in continental studies, using parameterization and GIS weighting. Besides the subroutines concerned with fire and its spatial relations, cells have a compartment for debris (including standing dead) that is separated from other litter, mostly more decomposable. Charcoal is a (nearly) inert part of soil carbon, analogous with "passive" humus in Post's Global Terrestrial Ecosystem Carbon (GTEC) model template. GTEC separates decomposers (bacteria, fungi; possibly soil animals) from their substrates, and coarse roots (>2mm?) from fine ones. GTEC grid simulations suggest Ontario's boreal forest and Great Lakes conifer, mixed and "northern hardwoods" region as a credible region for part of the "missing sink" of excess greenhouse gases. Local "LoTEC" and SimCYCLE template performance may be compared for forest types and zones of that region or for larch and mixed forests in Hokkaido (Sapporo eddy flux covariance tower).
Key words: Carbon cycle, Boreal forest, Disturbance regime, Model simulation