Savanna fire impacts on regional and global climate 4 February 2008 William Sea Natural Resource Ecology Laboratory Colorado State University CSIRO Marine and Atmospheric & Land and Water Research Canberra Ozflux08

PhD Research Questions Mortality: How do increases in tree mortality (juvenile and adult) change steady state woody basal area in a demographic-competition model compared with a traditional aggregated logistic model? Stochasticity: How does stochasticity in fire intensity and frequency impact woody dynamics relative to mean-field simulations? Initial Values: How do changes in initial values of basal area affect the steady state values (B *) in the demographic model compared with the logistic model? Competition Asymmetry: How do changes in the magnitude of asymmetric tree-grass competition lead to changes in steady state basal area values?

Juveniles: Adults: Basal Area: Grass Biomass: Demographic-Competition Model (1) (2) (3) (4)

Analytical Implicit Solutions * Basal area (B*) Set each equation to zero. Methods: Isolate critical bifurcation parameter, adult mortality (μ A ), on the left side of equation relating all parameters and steady state basal area values (B * ). Substitute in the full range of B * values and solve for μ A. Plot μ A vs B *.

Effects of Stochastic Fire Mortality Biennial Burns (2 yr) Mean Adult mortality = 2% Juvenile mortality = 50 % Grass Biomass (green) Tree Basal Area (black) Normalized to 1 = max

Stage 1: Compilation of data sets including global savanna tree cover, vegetation and soil carbon, and if possible seasonal variation. Stage 2: Calibrate CASA-CNP using data. Stage 3: Calculate emissions of aerosol particles, black carbon, CO2, Co, CH4 and N20 from savanna fires with frequency and extent based on remote sensing and fire load estimated from CASA- CNP. Run a global model to calculate radiative forcing based on savanna fire emissions. Postdoctoral Project Goal Improve the modelling of vegetation dynamic and emissions of aerosol and greenhouse gases from biomass burning of savannas in ACCESS

2007 Fires in Australia

Vander Werf (2007) Modis-derived global fire loss