Main Discussion Area > English Warbow
Evidence OTHER than MR Bows of 120+ bows?
brian:
Whilst following this thread with interest ,i was wondering what is the definitive minimum altitude that qualifies a yew stave to be classed as[high altitude],search as i may , i cannot find a E.U. directive that qualifies this.Also could this be open to question under the Trades Description Act.??? ;)
WillS:
The higher the altitude, the thinner the air, giving less oxygen so the tree grows slower. This creates a denser, tighter wood than trees growing lower down. It's the same with Pacific/Oregon yew. England doesn't have any really high yew-rich mountain ranges. If we did, I'd have bought a chainsaw and some hiking boots.
There were a lot of very nice looking yew trees in Snowdonia when I last visited however...
You're being tongue in cheek with your comment of course, but it would be interesting to know if anybody has done tests on yew from various altitudes with density results. There's probably a table somewhere in a book... There may well be a point where the density spikes dramatically at a certain altitude where the conditions really slow the growth.
Del the cat:
Sorry to be a constant nay sayer :-[ , but I think the altitude of the treeline is more about climate (temperature, wind etc) than oxygen. (errrr don't trees respire carbon dioxide? :-[ )
If you really want to know Mr Google will point to a multitude of learned papers.
Del
adb:
--- Quote from: WillS on November 26, 2013, 04:59:25 pm ---The higher the altitude, the thinner the air, giving less oxygen so the tree grows slower. This creates a denser, tighter wood than trees growing lower down. It's the same with Pacific/Oregon yew. England doesn't have any really high yew-rich mountain ranges. If we did, I'd have bought a chainsaw and some hiking boots.
There were a lot of very nice looking yew trees in Snowdonia when I last visited however...
You're being tongue in cheek with your comment of course, but it would be interesting to know if anybody has done tests on yew from various altitudes with density results. There's probably a table somewhere in a book... There may well be a point where the density spikes dramatically at a certain altitude where the conditions really slow the growth.
--- End quote ---
There's the same amount of oxygen at the top of Mt Everest as there is at sea level. 20.95%. The air around us in made up of 79% nitrogen and 21% oxygen. That doesn't change until the atmosphere ends. The atmospheric pressure is less. It's the difference in the partial pressure of oxygen that makes a difference. Humans existing at altitude use supplemental oxygen not because there's less, but because the pressure is lower. This is a bit off topic, but it's important to get your facts and info correct.
Trees growing at altitude do so slower due mostly to sunlight levels and poorer nutrition, not decreased oxygen levels.
WillS:
Well then I stand corrected!
Not too off topic and if somebody reading this learns something new it's never a bad thing!
Still, the overall point was that high growing trees are denser than the exact same tree growing lower down, which is a good attribute for bow wood and MAY have been an important consideration when outsourcing yew for warbows.
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