Sprouting Shrub Response to Different Seasons and Fuel Consumption Levels of Prescribed Fire in Sierra Nevada Mixed Conifer Ecosystems
Virtually all shrub species present in mixed conifer forests of the Sierra Nevada have evolved specialized adaptations to survive the frequent low intensity surface fires that characterized the fire regime of this ecosystem. In this study we examined the variable sprouting response of broad-leaved shrubs and hardwoods following prescribed fires burned under a wide range of environmental and fuel conditions. Shrub survival was often dramatically different between treatments (i.e., fuel consumption level and season of burn), species, and size classes within plant species. Of the four different burn treatments, survival of the shrubs and hardwoods was as low as 12% after early fall burns (high levels of fuel consumption) and as high as 79% after early spring burn treatments (moderate levels of fuel consumption). As much as 95% of the smallest size of the small classes of shrubs (i.e., those ≤50 g dry weight biomass) were killed by prescribed fires. In contrast, the majority of larger individuals survived fires of low-moderate consumption, but rates of survival declined with increasing levels of fuel consumption. Post-fire shrub physiognomy was significantly lower in crown volume, crown area, height, and aboveground biomass. The number of individual shrub stems per individual significantly increased after fire. Postfire biomass partitioning was different among sprouting species; in the deciduous-leaved Quercus kelloggii, the percentage of aboveground biomass composed of leaves was lower, and the percentage composed of woody tissues was higher than that of the evergreen-leaved Lithocarpus densiflorus. For. Sci. 36(3):748-764.
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Document Type: Journal Article
Affiliations: Professor of Forestry and Resource Management, University of California, Berkeley, CA 94720
Publication date: 01 September 1990