Postby webenda » Thu Dec 24, 2009 9:34 pm
Not frost, it is snow. The saguaro/freeze stuff is a True-Lie.
Cold weather and frost can kill the saguaro. (True.) That is why they do not grow above 4,000 feet. Saying it does not freeze where saguaros grow would be a lie for it does freeze in the lower desert. In that case the great, mostly aqueous bulk of larger plants protects them from temperature extremes. Heat absorbed through the surface during the day is stored in the mass of interior tissue, resulting in a fairly small temperature rise that doesn't reach a lethal level. The heat is slowly radiated and conducted back into the air during the cooler night. The same thermal inertia usually keeps the tissues above freezing on cold winter nights.
The freeze that accompanied the snow in the christmas photo I posted did not kill or damage any large saguaros. It warmed up to about 50 °F that day, the snow melted and the saguaros soaked up the sun's heat to get ready for the next night's freeze.
Reference:
http://www.desertmuseum.org/visit/exhib ... ptrail.phphttp://www.nps.gov/history/history/onli ... chap6c.htm
Last edited by
webenda on Thu Dec 24, 2009 11:26 pm, edited 2 times in total.
----Wayne----
Back when I was growing up, if you didn't start someth'n, there wouldn't be noth'n.
--Merle Haggard