Ministry of Forests

Cariboo Region Research Section

Assessing Aspen Competition on Pine Growth in the Cariboo Forest Region

Teresa Newsome, R.P.F.l

Historically Populus tremllloides (aspen) has been treated as a weed and only retained where it has not inhibited conifer growth. However, the market for aspen is increasing making it an economically viable species. As well, many of the advantages to maintaining hardwoods in a conifer stand are being recognized. Some of these are listed below (Daniel et al. 1979, Andersson 1985, Boyd 1985, Frivold 1985, Troedsson 1985, Walstad et al. 1987, Newton and Comeau 1990, Navratil et al. 1991):

Hardwoods can, however, limit conifer survival and impede growth. As Wagner and Zasada (1991) stated " Good vegetation management seeks to optimize the balance between positive and negative effects of non-crop vegetation within the context of silvicultural objectives." What we want to avoid is the "serious risk of competition" to crop species (Johansson 1985).

A conifer growing free of vegetation, including hardwoods and other conifers, will not have serious competition for light, moisture, or nutrients. Hardwoods growing close to conifers will increase the amount of competition. With minimal competition diameter growth is reduced; with further competition the height growth is reduced, and finally survival of the conifer is threatened. At what level of aspen competition is Pinus contorta var. Iatifolia (lodgepole pine) growth seriously affected? This study will try to address this question.

1. Research Silviculturist, Ministry of Forests. Cariboo Forest Region, Williams lake

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