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Author Topic: Dendrology question  (Read 1054 times)

Offline Maryland Beekeeper

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Dendrology question
« on: January 19, 2013, 10:24:06 AM »
I have heard of the large quantity of water to pass through tree on hot day. Would one expect this to pull significant heat out of Apis nest in hollow ? Mostly from sides, greenwood ?
Cheers,
Drew
p.s. Seems fair enough to me, but alas, as w/ thermodynamics, I find myself frustrated by ignorance :)
« Last Edit: January 19, 2013, 11:05:31 AM by Maryland Beekeeper »

Offline Vance G

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Re: Dendrology question
« Reply #1 on: January 19, 2013, 01:00:41 PM »
Forested areas are cooler than savannah grasslands.  Maybe this is why, but I don't know either.

Offline mikecva

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Re: Dendrology question
« Reply #2 on: January 19, 2013, 01:21:21 PM »
I would think not. The comb is not a good conductor of heat although the honey is better. The hollow of the tree will not have 'water' pass through it thus it will be difficult for the tree's veins to pick up the warmth of the nest in order to conduct the heat to the upper part of the tree. Maybe that is why we seldom see a tree sweat.  :lau:  Just my thoughts  -Mike
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Offline edward

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Re: Dendrology question
« Reply #3 on: January 19, 2013, 01:25:41 PM »
Maybe that is why we seldom see a tree sweat.

You've been looking in the wrong place, trees do nothing but sweat all the time through there leaves.

mvh edward  :-P

Offline Finski

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Re: Dendrology question
« Reply #4 on: January 19, 2013, 01:51:55 PM »
I have heard of the large quantity of water to pass through tree on hot day. Would one expect this to pull significant heat out of Apis nest

The water in trunk has propably same temperature as air. Leaves exist in summer.
Water goes near surface because often the trunk is rotten in deeper parts.
What about in spring when trees have no leaves?  Bees keep the temperature as same for brood and they ventilate the hive when it is hot.

What about in winter? What regulation you find then in hives?

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Offline Maryland Beekeeper

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Re: Dendrology question
« Reply #5 on: January 19, 2013, 03:00:34 PM »
Summer-basically a wooden radiator pulling water past nest ?
Fall-Sap slows ?
Winter-Sap flow slows/stops ?
Spring-flow begins  ?
Symbiotic ?

Offline little john

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Re: Dendrology question
« Reply #6 on: January 19, 2013, 04:31:17 PM »
Bees coat the inside of their nests with propolis, thus creating a waterproof cavity (which is then isolated from the normal tree physiology), although this coating may not be 100% complete until the second year of occupation.

LJ

Offline Finski

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Re: Dendrology question
« Reply #7 on: January 19, 2013, 05:22:07 PM »
Summer-basically a wooden radiator pulling water past nest ?
Fall-Sap slows ?
Winter-Sap flow slows/stops ?
Spring-flow begins  ?
Symbiotic ?

That brain using goes really too far. Have you taken your pills
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Offline BlueBee

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Re: Dendrology question
« Reply #8 on: January 19, 2013, 06:06:21 PM »
Do you have that glass hive finished yet?  Focus, focus, focus. :-D

With 100+ watts of heat per sq foot from the sun, a tree would quickly burn up if it didn’t have a way of shedding that incoming solar heat.  Like most beasts, trees are cooled by the evaporation of water.  When you’re as large as a tree, you need to pass a lot of water to accomplish that cooling.  However the active cooling is in the leaves, not the trunk. 

What happens in the trunk is probably a combination of cool water drawn up from the roots and heat conducted into the truck from the outside air.  My guess is the inside cavity would be cooler than the outside air, but not by a large amount, but I don’t know. 

The more interesting question to me is what effect all that water has on the insulation properties of the tree cavity.  People assume that because an Apis cavity is surrounded by 4” or 6” thick walls it is well insulated.  In fact that is probably not the case in the spring and summer when lots of water is saturating the wood.  Wood is only a descent insulator when those xylem cells are filled with air (not water).  Air is the real insulator in most things (including foam).

BTW… I might need some of those magic pills from Finland too. :)   

Offline Maryland Beekeeper

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Re: Dendrology question
« Reply #9 on: January 19, 2013, 06:08:06 PM »
I got a dissected poplar/nest stood up in the woods outside window :) Looking @ cross section  it seems possible, but I'm no dendrologist :) Thinking glass hive in a/c Slovenian b house might replicate nicely  ;)

Offline BlueBee

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Re: Dendrology question
« Reply #10 on: January 19, 2013, 06:16:11 PM »
What do they say about things that live in glass houses.  :-D

Interesting question about the tree trunk temperatures by the way.  I never gave it much thought until now, but now I'm thinking all that water in the wood would really wreak the insulation value of a tree cavity.  

Offline 10framer

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Re: Dendrology question
« Reply #11 on: January 19, 2013, 09:48:12 PM »
Bees coat the inside of their nests with propolis, thus creating a waterproof cavity (which is then isolated from the normal tree physiology), although this coating may not be 100% complete until the second year of occupation.

LJ

that might form a vapor barrier but it wouldn't stop heat transfer.  i would think that down here in the south the bees would actually cool the tree instead of the other way around unless the outer diameter of the hollow is pretty small compared to the outer diameter of the tree.  wood actually has a pretty good r-value so the thicker the walls the less heat transferred to the colony on hot days.  i'm not a physicist but i remember a little from college.