Forest Investment Account (FIA) - Forest Science Program
FIA Project Y062209

    Management of complex coastal mixedwoods in BC for productivity and free-growing
Contributing Authors: Thomas, Keith; Comeau, Phillip G.; Turner, Jennifer; Fielder, Peter P.; Harper, George J.
Imprint: [Victoria, B.C.] : [British Columbia Ministry of Forests and Range], 2006
Subject: Forest Investment Account (FIA), Alnus Rubra, British Columbia, Growth
Series: Forest Investment Account (FIA) - Forest Science Program
Red alder is a common component of low elevation CWH zone forests in South-western BC and often grows intimately with young conifer stands on highly productive sites. It is a strong competitor in young conifer stands and rapidly overtops juvenile conifers, often making it challenging to meet free growing obligations under current standards. Presently, many forest managers err on the side of caution and expend resources to control red alder to meet free growing requirements. Unfortunately, we are unable to determine whether these expenditures are warranted due to a lack of scientific data. This project provides preliminary best available information to assist in improving policies and practices around free-growing. The overall objective of this project is to provide science-based information useful for developing sustainable forest management strategies for complex coastal mixedwoods. More specifically it will provide much needed credible, scientific support to refine free growing standards for coastal forests, and guide decisions around policy and timber supply. This project utilises mixed alder-conifer experiments that were designed to study the competitive effects of red alder on conifers. The experimental sites are now old enough to assess the 11-yr free growing window. During the first year of this project (2004/2005) standard GY measurements and state-of-the-art light measurement techniques were used. A variety of competition indices that use measures of the number, size, proximity and location of broadleaf trees within a small plot centred on the subject tree were tested to estimate the intensity of broadleaf competition. In this study densities of red alder ranged between 0 and 400 trees/ha and basal area ranged up to 9 m2/ha, resulting in light levels ranging between 100 % and 37 % of full sunlight. These densities and light levels had only weak competitive effects on Douglas-fir and western redcedar on certain sites. We found consistent relationships between the basal area of red alder and light levels at the height of mid-crown for both western redcedar and Douglas-fir at the four study sites. However, on some sites conifer growth was positively related to red alder density. As expected due to its greater shade tolerance, western redcedar showed less sensitivity to the presence of red alder than Douglas-fir. We found that for the red alder densities in this study the radius of assessment plots should be at least 4 m. While one alder within a 1 m radius may be indicative of densities approaching 10,000 alder/ha, however, our results suggest that densities of up to 400 red alder/ha, may be acceptable and possibly desirable on some sites. These findings suggest the use of larger radius plots may be a consideration for evaluating red alder competition and free-growing in coastal conifer plantations. The second and final year (2005/2006) of this project focused on extending the research findings of the first year to the target audiences. The Extension Plan was finalised, an Extension Note and Stand Evaluation and Decision Aid (SEDA) were published, a site tour conducted and a journal article submitted.
Keith Thomas, Phil Comeau, Jennifer Turner, Peter Fielder, George Harper.
Related projects:  FSP_Y051209


Final Report (0.2Mb)
Complex Mixedwood Extension Plan (0.2Mb)
Red Alder Extension Note (JEM Vol 7, No 2, Article 5)

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Updated August 16, 2010 

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