What tree species gives the most BTUs per acre per year?

[wolfram]

I know that a precise answer is not possible given incomplete info, but please hear me out.  A question came up regarding planting trees for firewood production (in North America).  If one wanted to maximize the number of BTUs per acre per year, what species should one consider, all else being equal?  An important consideration is the shortest time to first harvest.

Cost per BTU is not a factor in the discussion.  In other words, low-density species, which may take more effort to handle, are fine.

Thank you.

[beenthere]

wolfram
Good friend of mine bought some WI property in '72 and after some intense research of just what you are asking, he planted soft maple (I believe it was silver). You might look at red maple. It is higher density than silver.

That decision was based on fast growth and wood density.  He was after 6 cords of wood a year, and planted aout 10 acres. He has since passed, and I don't think he realized any harvest of wood from that planting.

[Dodgy Loner]

That is an excellent question, and although I do not know the answer, I do believe that the question can be simplified somewhat. Since all wood has the same number of BTUs per pound, all you really need to know is what tree species would produce the most tonnage per acre on a dry weight basis per year.

I am familiar with one study on the Savannah River Site in South Carolina that determined that of four fast-growing species - loblolly pine, tuliptree, eastern cottonwood, and American sycamore - the American sycamore produced the most tonnage per acre on a dry weight basis. Sycamore was also considered desirable because it can reproduce via coppicing. The study was for a biomass energy source.

[Tom]

What is coppicing?

[Dodgy Loner]

Coppicing is a method of allowing a forest to reproduce by stump sprouts after harvesting. It is a traditional practice in Europe, where coppicing systems were, and in some areas still are, used to keep vigorous young stands of hardwoods for thatching spars, hurdle-making, wicker work, firewood, and charcoal production.

[Ron Wenrich]

I saw one operation where they coppiced ironwood in the understory and were getting firewood every 20-30 years.  It was in Germany and was grown underneath white oak and beech forests. 

Pine has a higher BTU value/lb than hardwoods.  8800 for pine and 8000 for hardwoods (if memory serves).  The higher pine BTU was due to the volatiles.

For the biomass market, they always pushed hybrid poplar and willow.  They grow fast and can yield 3-6 dry tons/yr.  Native hardwoods are rated at about 1 dry ton/yr.

[Ianab]

Problem is that for Firewood production, the fastest growing trees like Cottonwood, hybird poplar, willow and pine are less desirable to sell.

If you are dumping truckloads into an industiral size power plant then it doesn't matter what the species is, you jsut want the BTUs

If you are selling it as firewood, people tend to want hardwood, so the Soft Maples and Sycamore might give a better return, even if it was technically less wood. The ability to coppice them could increase your production once the trees are established.

Ian

[SwampDonkey]

Red maple coppices very well and grows fast. Sugar maple and yellow birch, not so great. Beech will, but dies before it reaches any size, I've never seen it grow a good sized stem like a red maple sucker will. Beech has been cut for firewood for years here and you just don't see the suckers get big, not even 5 inches.

[wolfram]

Great responses!  Exactly what I was looking for.  And super fast too!  Thanks.

Dodgy, I agree with your restatement of the problem.  I was not aware of the SC study or about Am. Sycamore.  I would like to learn more. 

Ron, thanks for the info on hybrid poplars.  It appears (from some initial google-ing) that they can be coppiced too.  Based on your comment about the biomass market, can I conclude indirectly that the hybrid poplar's annual BTU yield (per acre) is greater than pine's?

Ianab, I agree about the low desirability of the quick growing species in relation to marketable firewood.  Your second sentence describes my interest area almost perfectly.

SD, I have some red maple that I coppice for fun/experiment.  You're right, it's great stuff for that.  If it weren't taking over my woods, I'd love the stuff!

Others up this way keep telling me about black locust.  While a great firewood and a good grower here, it is hard for me to believe that it puts on BTUs as fast as the species that y'all are discussing.  Any thoughts on this?

[SwampDonkey]

Up here, where black locust is not native, it grows very slow. I see it sometimes on abandoned home sites and it's not very big.

[Ron Wenrich]

I would think that the hybrid poplar would yield more than the pine, especially in NY.  I have yet to see anybody that has mentioned pine as a species for biomass fuels.  All the studies suggest the hybrid poplar, willow or cottonwood. 

There was a study at Penn State back in the late '70s where they were looking at cutting poplar every 5-10 yrs and bundling the material.  I pretty sure that coppicing was being used as a reproduction method.  But, energy got cheap and that was put on the back burner.

If you're looking at biomass, I saw a figure of 11 tons/acre with switch grass.  A lot depends on what you're looking at doing with the material.  Pellets would be a nice fuel to make with the low density stuff. 

[WDH]

Switch grass is more like 6 tons/ac per year from what I have learned.  I guess that it depends on the quality of the site.

[Phorester]

I'd vote for black locust. 

[clearcut]

I worked with Eucalyptus plantations in California using short rotation (7 years) intensive culture  (drip irrigation and fertilizer) that were producing 6-10 cords per acre per year. Average DBH 4.5" and height of 44 ' with a dry weight of 87 tons per acre. BTUs similar to oak.

   http://ucce.ucdavis.edu/files/repositoryfiles/ca4206p19-68813.pdf

[Ron Wenrich]

Switch grass is more like 6 tons/ac per year from what I have learned.  I guess that it depends on the quality of the site.

Auburn study.  http://bioenergy.ornl.gov/papers/misc/switgrs.html  They even said they got 15 tons/acre the one year.

[wolfram]

Phorester, thank you for the vote.  Please substantiate.  I am looking for pertinent facts on black locust.  Thank you.

[Phorester]

Your question didn't stipulate what use the firewood would be grown for, so that might change my answer.  My answer was for growing firewood for home heating, or for a firewood producer to grow a crop to sell for the residential market. 

Black locust (Robinia pseudoacacia) is consistiently in the top of every list I have seen over the years for BTU production. It ranks up there with white oak and hickory.  But locust grows faster than the other top ranked tree species.  On just about any site that will grow hardwoods you can get 6" diameter trees in 20 years with black locust.  Faster growth in better soils. For oak and hickory you're looking at 30 years or more for the same size tree.

Other tree species like maple, poplar, sumac, can grow faster, but their BTU rating is much lower than locust.  That means that you have to grow, cut, handle, store, and burn twice as much wood to get the same amount of heat as with black locust.

So black locust gives you firewood sized trees in the shortest time, and with more BTU's per tree than about any other species.

Another source for more firewood info including a list of BTU production by tree species is:
http://forestry.about.com/od/firewood/a/firewood_chart.htm

[Dodgy Loner]

Other tree species like maple, poplar, sumac, can grow faster, but their BTU rating is much lower than locust.  That means that you have to grow, cut, handle, store, and burn twice as much wood to get the same amount of heat as with black locust.

You are right about this, Phorester, but wolfram mentioned that cost/BTU was unimportant in his intitial post:

Cost per BTU is not a factor in the discussion.  In other words, low-density species, which may take more effort to handle, are fine.

[tonich]

Coppicing is a method of allowing a forest to reproduce by stump sprouts after harvesting. It is a traditional practice in Europe, where coppicing systems were, and in some areas still are, used to keep vigorous young stands of hardwoods for thatching spars, hurdle-making, wicker work, firewood, and charcoal production.

The coppice system occurred to satisfy mainly the demand of  firewood and charcoal, requiring little or no silvicultural skills. In the middle ages it was commonly spread silvicultural system. However, in terms of sustainability and longlivity, nowadays new forester's challenge is the conversion back to their seed origin, which also will bring the opportunity to produce quality big timber . For example, the main longterm goal for over 80 % of governmental low-steam forest in Bulgaria is turning back to high-stem ones, mainly by shelterwood and selection approach.


Among the all coppice systems, Coppice-with-Standards management is an outstanding one.

Te coppice-with-standards system was presumably developed in France, where it was designed by J. B. Colbert for Louis XIV, king of France, between 1664 and 1683. Te aim was to fulfl the triune function of the king’s forests: (1) production of strong oak trunks used for building and navy, (2) production of frewood and timber, and charcoal, (3) pig grazing on acorns from the mature oaks of the top stand layer. Te features of the coppice-with-standards silvicultural system with prevailing oak in the top layer and coppice in the bottom layer proved very interesting from an economic point of view, and the coppice-with-standards form remained in use in many foodplain forests of Central Europe until the first half of the 20th century (Mezera 1956)

Did some further search and found an article from an American author, stating British Isles as an origin of the method ( ). Nevertheless this confusion, the article is descriptive enough:
http://www.agroforestry.net/overstory/overstory47.html

[ford62783]

i also agree on the black locust for the fastest and most btus per ton though if time was not a major factor i prefer beach though it dsnt have the btus that white oak and locust have i use it almost exclusively d to the availibility and the price per kbf isnt great