Year of Award

2017

Document Type

Thesis

Degree Type

Master of Science (MS)

Degree Name

Forestry

Department or School/College

W.A. Franke College of Forestry and Conservation

Committee Chair

Christopher Keyes

Commitee Members

Sharon Hood, Carl Seielstad

Keywords

fuel treatments; ponderosa pine; planar intersect, coarse woody debris

Subject Categories

Natural Resources and Conservation | Natural Resources Management and Policy

Abstract

In ponderosa pine ecosystems of the interior western United States, fuels reduction treatments are common, but the persistence of their effectiveness in mitigating fire behavior is poorly understood. We addressed this problem by analyzing ponderosa pine – Douglas-fir stands during more than two decades of response following fuel reduction treatments. An experiment at the Lick Creek Demonstration/Research Forest in western Montana was initiated in 1991 as a partnership between the USDA Forest Service and the University of Montana to evaluate tradeoffs among alternative cutting and burning strategies to reduce fuels and forest fire behavior while restoring historical stand structures and species compositions. One portion of the experiment tested a commercial thinning strategy, while a second tested a retention shelterwood strategy. Harvesting was performed in all treated units in 1992. Units were burned one-to-two years after harvesting, using different broadcast prescribed fire treatments to simulate a range of burning conditions. The units were measured prior to initiation of treatments in 1991, immediately following the completion of treatments in 1993-4, and in 2005 and 2015. Analysis included differences in 2015 canopy and surface fuel loads by treatment with fire behavior predictions using BehavePlus. Canopy fuel loading remained ~30% lower in all cut units in the thinning and 55-60% lower in cut and burned units in the retention shelterwood site. Canopy bulk density was 30% lower in cut units in the thinning but no different by treatment in the shelterwood and canopy base height was no different by treatment in either installation. Various surface fuel components exhibited differences by treatment in 2015 including 1-hr fuels, litter, and duff. The shelterwood site experienced much higher Douglas-fir regeneration, increasing canopy bulk density and reducing canopy base height. Under extreme weather scenarios, all sites were susceptible to passive or active crown fire behavior.

A second study utilized the 2015 fuels datasets to compare and contrast two common methods for sampling coarse woody debris fuel loads: fixed-area plot sampling and planar intersect transects. Both methods are commonly used in research and management but have tradeoffs in execution and accuracy that managers must consider. Our findings indicated that neither method provided a significantly different estimate at the stand level. However, plot-by-plot, fixed-area plot sampling was more likely to capture CWD presence; transects estimated zero load on 23-47% of plots. Results of this study will provide forest managers with guidance for measuring coarse woody debris in this forest type.

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© Copyright 2017 Katelynn J. Bowen