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Date Permissions Signed

5-16-2011

Date of Award

2011

Document Type

Masters Thesis

Degree Name

Master of Science (MS)

Department

Environmental Sciences

First Advisor

Homann, Peter S., 1953-

Second Advisor

Medler, Michael J.

Third Advisor

Sofield, Ruth M.

Abstract

In the summer of 2002, the 200,000-ha Biscuit Wildfire consumed a portion of the 150-ha Long-Term Ecosystem Productivity (LTEP) experiment in the Siskiyou National Forest, Oregon. The wildfire burned previously established 100-year-old conifer control and thinned experimental units, which allows comparison with prescribed burn and unburned units. This research evaluates the O horizon and mineral soil charcoal, a key fire-related soil component that affects physical and chemical properties. Charcoal C was quantified by a peroxide-acid digestion method developed for forest soils. Charcoal C was 17% of the organic C for a reference Australian Vertisol soil and 9% for a German Chernozem, which are similar to published values from a dichromate digestion method. The charcoal C of the Siskiyou LTEP soils was quantified in hand-sorted charcoal from the O horizon and in the < 4-mm fraction of the A (0-3 cm depth) and B1 (3-15 cm depth) mineral soil horizons. The mineral soils contained substantial amounts of charcoal C and no changes were detected as a result of prescribed or wildfire. Concentrations were 10 g charcoal C/kg in A horizon and 7 g charcoal C/kg in B1 horizon and areal masses averaged 1,860 kg charcoal C/ha in A layer soils and 5,260 kg charcoal C/ha for B1 layer soils. Charcoal C in the O layer averaged 18 kg charcoal C/ha prior to the fire and was increased by a factor of 5 by both prescribed fire and wildfire. The effect of thinning on wildfire-induced charcoal C changes was non-significant. Charcoal was formed at a rate of 0.5 - 6.0% of surface woody fuels consumed in the wildfire. Long-term soil C sequestration in the Siskiyou - LTEP soils is greatly influenced by the contribution of charcoal C, which makes up 20% of mineral soil organic C. The significant effect of recent fire on the O layer soils demonstrates the significant short-term effects of the Biscuit Wildfire and the dynamic nature of the O layer. This research reiterates the importance of wildfire and prescribed fire to soil C in a Southwestern Oregon coniferous forest ecosystem.

Type

Text

DOI

https://doi.org/10.25710/nv7t-ea59

Publisher

Western Washington University

OCLC Number

729749892

Subject – LCSH

Forest soils--Oregon; Biscuit Fire, Or. and Calif., 2002; Forest fires--Environmental aspects--Oregon; Fire ecology--Oregon; Forest ecology--Oregon

Geographic Coverage

Oregon

Format

application/pdf

Genre/Form

masters theses

Language

English

Rights

Copying of this document in whole or in part is allowable only for scholarly purposes. It is understood, however, that any copying or publication of this thesis for commercial purposes, or for financial gain, shall not be allowed without the author's written permission.

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