Height to diameter ratio as a competition index for young conifer plantations in northern British Columbia, Canada

Height to diameter ratio (HDR) was investigated as a potential alternative competition index for young lodgepole pine (Pinus contorta Dougl. ex Loud. var. (latifolia Engelm.) and spruce (Engelmann spruce (Picea engelmannii (P arry ex. Engel)) x white spruce (Picea glauca (Moench) Voss sp. glauca)) pl antations in northern British Columbia (BC). A completely randomized factor ial experimental design was used in the study, involving three replicates o f four levels of removal of competing vegetation. A one-way analysis of var iance (ANOVA) indicated significant (p < 0.01, F = 11.45) differences in HD Rs between treatments for one study site, but treatments at all other study sites were not statistically different. Generally, higher HDRs were obtain ed where percentage cover of aspen was relatively high and lower HDRs were obtained where percentage cover of aspen was relatively low. Planting posit ions of crop trees on the raised areas created by disc trench mechanical si te treatment, and timing of HDR measurements had significant influence on H DRs. It was concluded that HDR is a promising new addition to the field of vegetation competition indices. (C) 2000 Elsevier Science B.V. All rights r eserved.