Results from a Correlated Curve Trend Experiment on Spacing and Thinning of Coastal Douglas-fir

This document presents results from a long-term experiment examining the impact of spacing and thinning on coastal Douglas-fir plantations. The study, conducted over 28 years near Lake Cowichan, British Columbia, aimed to understand how different tree densities and thinning strategies affect various growth parameters like diameter, height, basal area, and total and merchantable volume. While acknowledging limitations due to site variation and a lack of replication, the report provides initial insights into managing Douglas-fir stands, emphasizing that higher density generally leads to smaller individual tree growth but greater overall stand volume, whereas thinning, especially heavy or early thinning, can positively influence tree size and merchantable volume.