Stand Structure and Growth Estimates for the Opax Mountain Silviculture Systems Trial

Catherine Bealle Statland
Forest Productivity and Decision Support
MoFR Research Branch, Victoria

Abstract

The treatments in the Opax Mountain Silviculture Systems Trial were designed to create a range in densities and patterns of structural elements important for wildlife habitat (large trees, large and small gaps, snags, dying trees, downed wood, and green retention). Single-tree selection, single-tree selection with reserve patches, or small patch cuts were prescribed in terms of fixed percentage volume removals in order to contrast varying degrees of impact on the original overstorey. However, silviculturalists will want to know quantitative information on the residual stand structures which resulted, how these structures compare to conventional prescriptions, and how they might be expected to develop in the near and distant future. Of the many partially-cut IDF stands in the Kamloops Region, few have been monitored rigorously with thorough pre- and post-treatment descriptions and long term observation. The difficulty and expense involved in sampling and tracking these heterogeneous and highly variable stands is one reason for this.

The stand structures of all twelve treatment units in this trial were thoroughly measured immediately before and after harvesting (1993/94 dormant season). Tree species, height, diameter at breast height, standard damage and defect codes, past increments, spatial distribution, ages at stump and breast height were sampled on 159 0.04-hectare fixed-area strip plots. Advanced regeneration was tallied on 0.005-hectare circular plots. Plot aspect, slope, mesoslope position and elevation were also recorded. The "before" and "after" compiled data summaries will be presented and the shortcomings and limitations of the sampling approach discussed.