Biomass production and fire regimes

Cumulative forest age distribution.

Average forest age distributions under fire cycles of 6 638 (a and b), 1 885 (c and d), 1064 (e and f), 297 (g and h), and 125 (i and j) years with different initial conditions. The graphs in column A were simulated from a randomly initiated landscape, and graphs in column B were simulated from a real landscape with a large area of older forests.

Time series of the ideal historical fire data set used in this analysis.

Simulated annual fire number (A), area burned (B), and mean forest age in years (C) of the constructed ideal fire data set.

Fire cycles estimated from different numbers of fire maps and three different starting years.

Fire cycles estimated from stand-origin maps at 10-year intervals by a nonlinear curve-fitting procedure resulted in spatial fire ignition patterns in Alberta (1961–1995): (a) lightning–caused fires and (b) human-caused fires (gray area represents forested land).

Effect of fire suppression on fire regimes: (a) fire cycle, (b) numbers of fires per year, (c) mean annual area burned, and (d) mean fire size.

Effect of fire suppression on forest dynamics is shown in terms of mean forest age (a and b), mean volume (c and d), mean basal area (e and f), mean volume increment (g and h), and mean volume burned (i and j).

Simulated forest age distributions under different fire cycles.

Age-specific mortality and stable forest age distributions.

Age-specific mortality and stable forest age distributions.

The simulation results of stable age distributions (right column, g-l) under different curves (left column, a-f), including constant (a and g), linear increase (b and h), linear decrease (c and i), logistic curves (d and j), and domed shapes (e and k, as well as f and l).