Reconstructed height growth trajectories of white spruce (Picea glauca) following deciduous release

Abstract

My study evaluated the “true” white spruce (Picea glauca [Moench] Voss) height growth potential in sites released from deciduous competition. Stem analysis, plus re-measurement data from 60 and 80-year-old trials were used. Interpolated site index (SI, height at breast height age 50) of released spruce was not significantly increased due to late treatment application. However, their height increment 50 years following treatment was elevated by 2.1m. Existing height-age equations for this region showed varying suitability. I fit a new height-age model which allowed for delayed release, this showed a potential 4.1m increase in spruce SI due to release. In a site-specific model, deciduous basal area removal explained significant variation in spruce SI. This model indicated a 7m gain from early release from heavy competition. These results provide a first long-term estimate of the degree that spruce height growth from mid-age to maturity can be increased by deciduous competition removal.