Southern Interior Forest Region

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Managing ingrown Douglas-fir stands for biodiversity, forage, and timber: the Farwell Canyon project fifth-year post-treatment results

Author(s) or contact(s): O.A. Steen and H.M. Armleder
Source: Southern Interior Forest Region
Subject: Wildlife, Wildlife Ecology
Series: Technical Report
Other details:  Published 2008. Hardcopy is available.


The Farwell Canyon project was established to explore treatment options for enhancing undergrowth vegetation cover, forage production, and tree growth in densely ingrown Douglas-fir stands of the Interior Douglas-fir very dry mild (IDFxm) biogeoclimatic subzone. Fire scar and tree age analyses along with stand structure observations suggest that many of these ingrown stands were considerably more open before European settlement.

Stem reduction treatments applied to two ingrown sites in 2001 included logging only (L), logging plus juvenile thinning (LT), and logging plus thinning plus underburning (LTB). No-treatment (NT) areas were also established. The logging treatment was modified from standard practices to harvest small merchantable stems and to initiate thinning of juvenile stems. The objective of this report is to compare third- and fifth-year (2003 vs. 2006) vegetation composition, forage production, and tree regeneration responses to these treatments on one site.

Douglas-fir regeneration density increased in all treatments between 2003 and 2006. Cover of grasses increased substantially, due primarily to increased cover of pinegrass (Calamagrostis rubescens). The number of plots with bunchgrasses increased even though mean cover of bunchgrasses did not increase significantly. Shrub and forb cover remained generally low on all treatments. Biomass of combined forbs and graminoids increased significantly from 2003 to 2006 but did not differ significantly among treatments.

These early results suggest that the logging treatment, with or without additional treatments, is leading to increased vascular plant cover and forage production. Tree regeneration density is still relatively low. The thinning and underburning treatments have reduced the fire hazard and prepared the stand for follow-up treatments to maintain a more open stand structure.

The stand treatments applied in this study should be combined with other treatments to create various stand structures across the IDFxm landscape, corresponding to historic variability of disturbances within the IDFxm subzone.

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Updated January 16, 2009