We evaluated effects of fire on Oregon white oak communities and regeneration at Fort Lewis, Washington. Oak stands burned by prescribed fire over the period 1994-1999 were evaluated for tree damage, mortality, and canopy tree resprouting. Neither single nor double fires had a large effect on basal area, but double fires significantly reduced oak density. Basal sprouting of oaks was related more to stand basal area reduction and crown damage than to bole damage. Small mammals preyed heavily on acorns exposed on the ground. Acorns buried in previously charred microsites in the field had higher emergence than ash treatment or the unburned control. Greenhouse studies showed little effect of soil heating prior to sowing on oak seedling survival, cover, height, or mass at the end of one growing season. Treatments with added ash reduced oak survival, cover, and height. Cover and mass of competing plants was also reduced with ash addition. Scot’s broom density declined from the control with added ash, but increased in heated soils. Nutrient analyses of oak seedlings showed little interpretable effect of heat or ash treatments. Fire is important in the dynamics of oak communities, but appears not to play an obligate role in seedling recruitment.
Cascadia Prairie-Oak Partnership
Providing coordination for the technical prairie community in the Willamette Valley, Puget Trough, Georgia Basin (WPG) ecoregion and beyond.