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RESEARCH ARTICLE
Contents Vol 15(1)

Heterogeneity in fire severity within early season and late season prescribed burns in a mixed-conifer forest*

Eric E. Knapp A C and Jon E. Keeley B
+ Author Affiliations
- Author Affiliations

A US Forest Service, Pacific Southwest Research Station, 3644 Avtech Parkway, Redding, CA 96002, USA.

B US Geological Survey, Western Ecological Research Center, Sequoia and Kings Canyon Field Station, HCR 89 Box 4, Three Rivers, CA 93271, USA.

C Corresponding author. Email: eknapp@fs.fed.us

International Journal of Wildland Fire 15(1) 37-45 https://doi.org/10.1071/WF04068
Submitted: 13 December 2004  Accepted: 9 September 2005   Published: 6 March 2006

Abstract

Structural heterogeneity in forests of the Sierra Nevada was historically produced through variation in fire regimes and local environmental factors. The amount of heterogeneity that prescription burning can achieve might now be more limited owing to high fuel loads and increased fuel continuity. Topography, woody fuel loading, and vegetative composition were quantified in plots within replicated early and late season burn units. Two indices of fire severity were evaluated in the same plots after the burns. Scorch height ranged from 2.8 to 25.4 m in early season plots and 3.1 to 38.5 m in late season plots, whereas percentage of ground surface burned ranged from 24 to 96% in early season plots and from 47 to 100% in late season plots. Scorch height was greatest in areas with steeper slopes, higher basal area of live trees, high percentage of basal area composed of pine, and more small woody fuel. Percentage of area burned was greatest in areas with less bare ground and rock cover (more fuel continuity), steeper slopes, and units burned in the fall (lower fuel moisture). Thus topographic and biotic factors still contribute to the abundant heterogeneity in fire severity with prescribed burning, even under the current high fuel loading conditions. Burning areas with high fuel loads in early season when fuels are moister may lead to patterns of heterogeneity in fire effects that more closely approximate the expected patchiness of historical fires.

Additional keywords: fire ecology; landscape heterogeneity; prescribed fire; season of burning.


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* This article was written and prepared by US Government employees on official time and is therefore in the public domain and not subject to copyright.