BTUs in large branches versus the main trunk wood

[muncybob]

I'm in the process of cutting several hard maples. Of course, there are a lot of branches to deal with and I'm saving the ones that are 3+ inch diameter for firewood. I remember reading somewhere that the branches are more dense and have higher btu ratings/pound than main trunks....????

 

[bigbarf48]

I seem to recall hearing that somewhere as well

 

[bmblank]

I'm sure the btu/unit weight is the same, but they're more dense so then the but/unit volume would be higher. If what they say is true.

 

[blazincajun]

It all comes down to growth rings. A tree is most dense where the growth rings are closest. At varying periods of a tree's life, growth will either speed up or slow down according to microsite changes around the tree. As a tree grows in an open canopy, the trunk and branches are growing at a rapid pace and the growth rings are usually large. As a tree ages those first upper branches begin to dominate (i.e., shade), the lower branches. Since the lower branches growth slows down the growth rings become smaller and more dense. The same thing happens with the trunk of a tree; however, if the tree is getting max sunshine from the sides and above, then the lower branches will be more dense. Also, as the tree gets more crowded it usually has fewer older branches as they self prune. So the trunk will be more dense than the upper branches, but not neccesarily the lower branches . Max sunlight with some tree competition is good.

 

[Hickorynut]

With some species as maples, ash and locust it probably comes down to tighter growth rings as the branches or trunks are mostly the same either heartwood(locust) or sapwood(maples and ash). But I know with oak I much prefer the trunk than the branches as the trunk has way more of the denser and more rot resistent heartwood than sapwood. So maybe it is species dependent.

 

[BobUrban]

What is heavier a ton of feathers or a ton of bricks??? BTU's are based on density of the wood but per LB it is all the same so the only difference is how much it weighs per volume. All that said - there is no difference.

 

[Backwoods Savage]

Bob is right. A pound is a pound no matter if it came from the trunk or the limbs. I've never noticed a difference, but then, I never paid that close of attention to it either; just could see no need.

 

[Wood Duck]

I think the limbs would tend to have a higher ratio of sapwood to heartwood. Sapwood is less dense and rots more easily, so it is less desirable. That makes me think the limbs are less desirable, not more.

If I am cutting at home, where I have lots of time to process a tree, I save as much of the branches as possible.

 

[Applesister]

I have never come across anything in my travels that makes reference to this. But as one person stated...a pound is a pound.
If anything I would feel densities of limbs would be specific to the species. Fruit trees and nut trees for example...well, say cultivated trees.
Weight bearing limbs. I dont know.
On certain species I keep everything, on others I toss limbs in the woods. Other limbs get chipped.

 

[Paulywalnut]

I still think two big chunks of red oak will burn longer than a stove full of branches split.

 

[Applesister]

I think 5 oak limbs will burn hotter and longer than 2 big poplar chunks.
;-)

 

[Ehouse]

I have a lot of White Birch growing under the canopy that fits this description. Slow growing, but tall and straight, with few branches. I'm cutting them between 8" and 12". Very dense and heavy even after proper seasoning, they burn more like Sugar Maple than Birch grown in the open. Perfect firewood!