Introduction

Canada Yew (Taxus canadensis Marsh.) is a low evergreen shrub found growing predominantly in the shaded understory of moist forests in eastern Canada. It can also thrive in more open areas such as harvest blocks and plantations. Recent research has revealed that this shrub contains several compounds which have been proven useful in the fight against cancer. With the potential commercialization of Canada Yew, research is needed to ensure that the shrub is managed in such a way so as to safeguard its sustainablity. The shrub must also contend with browsing by white-tailed deer, which has been found to cause its eradication in some areas of the United States.

Objectives

At the request of the Prince Edward Island Department of Agriculture and Forestry, a cooperative study was initiated in 1997 with the Canadian Forest Service to address the following objectives:

• determine the growth response of Canada Yew following harvesting by two methods - clipping with shears and breaking off the tips by hand;
  
• determine the growth response of Canada Yew following different harvesting intensities; and
  
• obtain additional baseline information on age, biomass, mode of reproduction, and potential rate of spread of Canada Yew on Prince Edward Island.

The results of this research has

• resulted in the development of more-refined sustainable management guidelines for the harvesting of Canada Yew on Prince Edward Island; and
  
• tested the reliability of the newly created harvesting guidelines for possible improvement and refinement.
  

Methodology

Two study sites have been established on Prince Edward Island - one in a hardwood stand and the other in a softwood stand. A third study site is in the process of being established. Each study site contains 30 plots, with each plot containing eight individual Canada Yew plants around a tree at the center of the plot. This resulted in a total of 240 plants per site. One of eight treatments was assigned to each of the plants in a plot:

• biomass plant;
  
• control (no harvest);
  
• "thinning out" of 38 cm (current guideline) by clippers;
  
• "thinning out" of 38 cm (current guideline) by hand;
  
• "thinning out" 75% of green length of each branch by clippers;
  
• "thinning out" 75% of green length of each branch by hand;
  
• shear current green foliage by clippers; and
  
• shear current green foliage by hand.

The following measurements will be taken for each plant:

• total length (cm);
  
• live foliage length (cm);
  
• vertical height (cm);
  
• remaining length of plant (cm);
  
• root collar diameter at ground level (mm);
  
• number of branches > 38 cm;
  
• average length of branches > 38 cm (cm);
  
• average length of branch stubs > 38 cm (cm);
  
• average increment growth for the last 3 years (cm); and
  
• weight of material removed from the biomass plant (kg).
  

Results and Conclusions

Descriptive statistics, box plots, and one-way analysis of variance show no significant differences between the Canada Yew plants before treatment. Not enough time has elapsed since the treatment of the plants for any significant growth responses to have occurred. However, two observations have been made:

• harvesting of the branches by hand is neither efficient nor desirable; and
  
• growth response following the treatments is slow.