Does the growing environment affect weight/BTU rates?

[CJRages]

Hope you all understand my quesiton - if not, here it is in math word problem format:

For example:
One bright sunny day Suzie planted two acorns from a single red oak tree 75 years ago. She planted one in the middle of the deep dark hilly forest with two inches of top soil and clay for dirt with little sunlight and lots of competing trees. The same day Suzie planted the other acorn in the middle of her father's corn field in the wide open, three feet of top soil and no competing trees with plenty of moisture. Surprisingly both trees survived those long 75 years.

Now its 2010 and Harvey decides to take the two red oak trees for firewood. The tree that grew with competition in the forest is straight and tall, but only 1 ft in diameter. Growth rings were tightly compacted due to slow growth. This tree nets out to provide 1.0 face cord of firewood. Meanwhile the tree that had been in good soil with full sun has a 3.5 ft diameter and provides 6 face cords of firewood. As you can guess the growth rings were more widely spaced.

When all the wood has been fully seasoned in 2013 to 20% moisture content by weight, will the oak firewood from tree planted in the woods be better, heavier, contain more BTU per cubic foot than that which grew rapidly in the open?

Thanks.

 

[PNWBurner]

Hmmm. I dunno, good question.

Does a tree growing under adverse conditions tend to be denser than a tree growing under ideal conditions?

I bet there's also some genetic variation within trees of the same species too so it might be hard to tell.

 

[begreen]

Absolutely yes. Take a spruce grown here in the damper, western lowlands and compare it to one growing at high altitude on the dry side of the state (or anywhere near the treeline in the Rockys). The density difference is like comparing softwood to hardwood. We have firs that put on 1/2" girth per year (1/4" growth rings) and get big very fast. But in the mountains, they may take several years to put on that 1/2" growth.

 

[man of stihl]

This should be an interesting discussion.

 

[CJRages]

Absolutely yes. Take a spruce grown here in the damper, western lowlands and compare it to one growing at high altitude on the dry side of the state (or anywhere near the treeline in the Rockys). The density difference is like comparing softwood to hardwood. We have firs that put on 1/2" girth per year (1/4" growth rings) and get big very fast. But in the mountains, they may take several years to put on that 1/2" growth.

If this is the case, then all those BTU charts (that we love by the way) could be easily flawed/inaccurate unless those performing the tests were using wood that came from equivalent growing conditions. I have never heard this aspect discussed. Makes me wonder how accurate those charts really are.

 

[Backwoods Savage]

Not sure but I don't think there would be a lot of difference. Some, but not a lot.

The big difference will be in the tree that has grown in the open will be loaded with limbs; lots and lots of limbs but the one in the woods will tend to go up a long ways before any limbs. Of course this makes the woods oak worth much more than the open one because of lumber value. The one in the open will definitely give more firewood but good lumber is worth a lot more than what one can get for firewood. As for me, I really do not like cutting those limby trees. It is a lot of hard work doing all those limbs. But, that is where you get more rounds of the size that will fit your stove.

 

[smokinj]

Not sure but I don't think there would be a lot of difference. Some, but not a lot.

The big difference will be in the tree that has grown in the open will be loaded with limbs; lots and lots of limbs but the one in the woods will tend to go up a long ways before any limbs. Of course this makes the woods oak worth much more than the open one because of lumber value. The one in the open will definitely give more firewood but good lumber is worth a lot more than what one can get for firewood. As for me, I really do not like cutting those limby trees. It is a lot of hard work doing all those limbs. But, that is where you get more rounds of the size that will fit your stove.

I am with dennis on this one....but I don't mind doing limbs and use the truck for milling (beautiful wood) but your not going to get more than 10-15 ft if your lucky....but its much wider so there is still some good lumber in the urban forest!

 

[ihookem]

I took a bunch of beams out of a 150 yr old log home. The beams were 8" dia. and had 100 rings or so. It was the heaviest wood I ever burned and it burned for a long time. I also get lots of elm here in farm country, I also get it in northern wisconsin in the wood. An elm log 6" dia. in northern wisconsin will be 50 yrs. old. In farm country it is 15 yrs. old. The norhtern elm burns way better. So I say the answer is yes.

 

[SolarAndWood]

As far as firewood goes, and setting aside processing effort required, isn't a pound of dry wood a pound of dry wood?

 

[begreen]

If this is the case, then all those BTU charts (that we love by the way) could be easily flawed/inaccurate unless those performing the tests were using wood that came from equivalent growing conditions. I have never heard this aspect discussed. Makes me wonder how accurate those charts really are.

We see this all the time in dimensional and trim lumber. It is really rare to get nice tight grained wood anymore unless it comes from the wild. Farm grown wood has much wider grain and just isn't as tough or dense. That's in part because it is planted for rapid growth and quicker harvests.

The btu charts are just an average. If you compare some from different sources you will see that they don't have the same exact values for a specific tree. This could be lab testing methods or the region the tree was grown in.

http://extension.usu.edu/forestry/HomeTown/General_HeatingWithWood.htm
http://mb-soft.com/juca/print/firewood.html
http://firewoodresource.com/firewood-btu-ratings/

This chart might be a bit more interesting because it lists wood by densities. Notice the wide range for certain wood species like box, spruce, sycamore and willow.
http://www.engineeringtoolbox.com/wood-density-d_40.html

 

[Battenkiller]

A general rule is that for hardwood, widely spaced rings (faster growing) means stronger and denser wood. That's why you look for that in a good axe handle. For conifers, the opposite is true. Musical instrument tops are almost always made of conifer wood. The closer the grain, the stronger the top (although not always the best tone). I remember getting into an argument with my botany prof in college about this. He was a tree expert, and he insisted that all trees with widely spaced rings are denser, but I was able to demonstrate that he was wrong.

As far as what conditions lead to faster growth, it is not as uniform as you might think. Some species of hardwood grow faster in the open and others grow faster when competing for light while under the canopy. I don't remember which ones are which, but I know I came across info about this on the web very recently.