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| Canada yew, a common understory shrub, is a source of chemicals called taxanes that are used in cancer drugs. . |
After six years, OFRI research scientist Tom Noland is taking off his Canada yew hat. He has wrapped up his second Canada yew research project, this one focusing on harvest of plants growing in the wild, with results appearing in the July/August 2011 issue of The Forestry Chronicle.
“Commercial harvesting of Canada yew in Ontario’s forests began in 2003 but without a policy in place to guide it,” Noland says. “Now we have the data we needed to confirm that the Canada Yew Association’s sustainable harvest guidelines, which call for moderately harvesting three year old shoots plus allowing four years of regrowth before harvesting again, work for Ontario.”
Canada yew is a low evergreen shrub that grows in the forest understory across most of eastern Canada and the northeastern United States. It is an important wildlife species – deer love to munch it, although it is highly toxic to humans. And it is economically valuable because its foliage contains useful chemicals called taxanes.
“Take the taxane known as Paclitaxel, for example,” Noland says. “Canada yew has higher concentrations of this taxane than most other yew species, and it is the active ingredient in Taxol®, one of the most valuable cancer drugs in the world. Our study shows that careful harvesting of wild yew biomass for anticancer chemicals can be done sustainably in Ontario. That is good news for the northern economy.”
Some of the more interesting results of the study, according to Noland, are that harvest season and stand location didn’t seem to affect how much yew grew after harvest and that yew grows back nicely as long as the harvest is not too severe.
In addition to studying wild yew harvesting, Noland also investigated growing Canada yew as a farm crop in northern Ontario, work that included selecting individual plants with high growth rates and taxane concentrations and determining how best to propagate and grow them in plantations. For the results of that research, see Canada Yew: Developing a Value-Added Crop for Northern Ontario (Forest Research Report No. 172).
So what’s next for Noland, a tree biochemistry scientist with a keen interest in non-timber forest products? “I am now working on analyzing vegetation samples for a project on the effects of disturbance on caribou forage quality, have set up a study to look at the effects of the herbicide glyphosate on eastern white cedar, and am analyzing samples of bio-oil derived from wood liquified in MNR’s transportable biorefinery to look for possible useful chemicals,” he reports. “I enjoyed the yew research very much, especially the fall assessments which got me outside after bug season, but I am already moving on to new challenges.”
