Presentation Type

Poster - Campus Access Only

Abstract

The effect of varying thinning treatments on the accumulation of woody debris within western larch forests

Very little is known about how forest thinning affects accumulation of dead wood. Dead wood is ecologically important, providing carbon storage, wildlife habitat, and, as woody surface fuel, contributing to fire behavior. Alternative thinning regimes were studied to discover their effect on biomass of snags (standing dead wood), fine woody debris (FWD; 7.6 cm in diameter) in pure western larch (Larix occidentalis) stands. This study uses a randomized block design, with each of 10 treatments replicated once at four locations (i.e., blocks) in western Montana. Treatments are a 3x3 factorial cross of stand density (494, 890, 1680 trees ha-1) and thinning frequency (1, 2, or 4 thinning entries), and an untreated control. Within each of the 400.9 m2 treatment plots, total height and diameter at breast height was measured for all snags, as was total length and diameter at each end and the midpoint of every CWD particle. FWD was sampled in four 1 m2 subplots within each treatment plot. FWD samples were sorted, dried, and weighed in the laboratory. The treatment thinned to 494 trees ha-1 in 2 entries had the lowest total dead biomass (13.3 Mg ha-1) while the control treatment had the highest (53.2 Mg ha-1). CWD stocks increased, while FWD stocks decreased, with thinning frequency; snag biomass increased strongly with density. CWD was rare in the unthinned controls, in which >90 % of total down woody debris were in the FWD size class. Thinning strongly decreases woody debris accumulation relative to unthinned control areas, which has direct implications for management of potential fire behavior and carbon storage: lower fuel loads in thinned forests should lead to reduced potential fire intensity, but at the expense of total carbon storage.

Category

Physical Sciences

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Apr 15th, 11:00 AM Apr 15th, 12:00 PM

Effects of thinning on Larix occidentalis dead wood accumulation

The effect of varying thinning treatments on the accumulation of woody debris within western larch forests

Very little is known about how forest thinning affects accumulation of dead wood. Dead wood is ecologically important, providing carbon storage, wildlife habitat, and, as woody surface fuel, contributing to fire behavior. Alternative thinning regimes were studied to discover their effect on biomass of snags (standing dead wood), fine woody debris (FWD; 7.6 cm in diameter) in pure western larch (Larix occidentalis) stands. This study uses a randomized block design, with each of 10 treatments replicated once at four locations (i.e., blocks) in western Montana. Treatments are a 3x3 factorial cross of stand density (494, 890, 1680 trees ha-1) and thinning frequency (1, 2, or 4 thinning entries), and an untreated control. Within each of the 400.9 m2 treatment plots, total height and diameter at breast height was measured for all snags, as was total length and diameter at each end and the midpoint of every CWD particle. FWD was sampled in four 1 m2 subplots within each treatment plot. FWD samples were sorted, dried, and weighed in the laboratory. The treatment thinned to 494 trees ha-1 in 2 entries had the lowest total dead biomass (13.3 Mg ha-1) while the control treatment had the highest (53.2 Mg ha-1). CWD stocks increased, while FWD stocks decreased, with thinning frequency; snag biomass increased strongly with density. CWD was rare in the unthinned controls, in which >90 % of total down woody debris were in the FWD size class. Thinning strongly decreases woody debris accumulation relative to unthinned control areas, which has direct implications for management of potential fire behavior and carbon storage: lower fuel loads in thinned forests should lead to reduced potential fire intensity, but at the expense of total carbon storage.