Non-crop vegetation on regenerating forest lands is often viewed as being uniformly detrimental to the establishment and growth of commercial tree species. This assumption is ingrained in our traditional concepts of land stewardship and efficient commodity production. The "free-growing" designation for a regenerated stand defines the extent of basic silviculture for which forest licensees are responsible in British Columbia, and the free-growing definition requires that crop trees be taller than all surrounding vegetation, regardless of species. Such a policy may represent an inappropriate extension of agricultural paradigms to silviculture, for evidence is mounting that (1) not all effects of vegetation are negative, and (2) different plant species are not equivalent in their effects.
An experiment was undertaken in the UBC Malcolm Knapp Research Forest near Maple Ridge, B.C., in order to measure the competitive effects of the dominant, non-crop, plant species found in early, post-logging, successional vegetation. This work quantifies some of the impacts of different plants described by Haeussler et al. (1990) in their review of the earlier literature. The study was conducted on two cutblocks in the dry maritime subzone of the Coastal Western Hemlock biogeoclimatic zone (CWHdm); results may or may not be more widely applicable.
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Updated April 17, 2007