FRDA Basal Area Response Nine Years After Fertilizing and Thinning Western Hemlock

This FRDA Report #137 investigates the basal area response of immature coastal western hemlock stands to fertilizing and thinning treatments on northern Vancouver Island, nine years after application. The purpose is to understand how these silvicultural practices affect tree and stand growth, particularly focusing on net basal area response, which is a measure of the cross-sectional area of tree trunks. The study found that while thinning alone significantly improved growth, the best results were achieved by combining fertilization with thinning, as this concentrated the additional growth onto fewer, more valuable stems, even though the total basal area removed by thinning was not fully recovered within the nine-year period. The research also provides equations for estimating net basal area response, offering practical tools for forest managers considering these interventions.