Establishing a sustainable harvest for canada yew (Taxus canadensis marsh.) in Ontario

Abstract

In 2003, commercial harvest of Canada yew (Taxus canadensis Marsh.) in Ontario began—but without a sustainable harvest policy. In 2005, we began to determine the sustainability of three harvest intensity treatments at three sites in central Ontario. Harvest treatments were labelled control (no initial harvest), light (two-year-old shoots removed), moderate (three-year-old shoots removed), and severe (seven-year-old shoots removed). We also looked at effects of harvest season and light levels on shoot regrowth. After three and four years, severe-harvest plants yielded less than half the biomass of the initial harvest, while biomass from moderate-harvest plants was about equal to the initial. Biomass from light-harvest plants generally increased. Moderate light levels stimulated more first-year regrowth in all plants than low light levels did but increased only Year 2 regrowth in severe-harvest plants. Spring harvest reduced first-year regrowth only. Comparing biomass of moderate-harvest plants after three or four years with initial moderate-harvest biomass suggested similar growth rate across time periods. Our results concur with Canada Yew Association sustainable harvest guidelines: Moderately harvesting three-year-old shoots plus allowing four years of regrowth before reharvest ensures sustainable harvest, at least through one harvest cycle.