Cords per acre sustainably

[DouginUtah]

Here is a post that I read on another forum....

I'm going to stick my neck out into a complex question and hazard a guess that, at least in the Northeastern US where I am, a person can cut about 1/4 to 3/4 of cordwood per acre per year on an ongoing basis. This depends greatly on local soil conditions as well as tree species mix, silviculture practices, harvesting practices etc. 1/4 to 3/4 still has a factor of 3 spread.

This number is one that I've gleaned from various firewood/timber readings over the years. I am not a forester and only recently in the past 3 years have I started cutting firewood from a large woodlot that I have access to (but do not own) so by all means, if anyone out there has thoughts on firewood production sustainability numbers, I'd love to hear them too.

Is 1/4 to 3/4 cords per year about right?

-Doug

[Max sawdust]

Doug,
I am interested in hearing from the foresters also.  Sounds low to me, even if you only cut dead or storm damaged trees, in a healthy and diverse stand.
Max

[crtreedude]

I don't know about cords of wood, but in the North, isn't the rule of thumb is 2 cubic meters of hardwood growth per Hectare per year? (Hectare = 2.5 acres roughly)

If a cord = 128 cubic feet and a cubic meter = 34.38 cubic feet

I think we have the following

(2 / 2.5)  * (128 / 34.38) = 2.9 cords.

So, I would think that 2.9 cords of hardwood per year would be a reasonable number.

And then again, I could be way off on my numbers.  ;)

Very interested in what others say.

[IL Bull]

Using your figures it looks like you would only get 27.504 cubic feet per acre.
(2/2.5) = .8x34.38=27.504 or am I corn-fused?

[Tom]

I tend to be a little simplistic, but, doesn't it matter which acre you're talking about?    I've got some of them that would be hard pressed to provide a bushel of grass clippings much less a cord of firewood. ;D

[beenthere]

DouginUtah
You've listed quite a range of yield. I have heard of a cord per acre down to ½ cord (talking full cords here, not the 'misleading' face cord   ).  I've heard a lot of comment that a 10 acre woods could sustain a cut of 6 cords per year. That is in the ballpark of what you describe. Granted there are a lot of variables, one big one is the maturity of the forest you are talking about. A friend of mine heard these numbers and bought a farm with 10 acres of woods that had been heavily pastured over the years, and there was no way it would yield 6 cords of wood per year for more than a few years at best. He was real disappointed that he felt misled. Also, if mature and potential sawlog trees are also included in this yield, then the yield may be low. Many variables for a pat answer on this one, IMO.

[SwampDonkey]

Well I guess we must be speaking of hardwood forests, or I'm going to assum so.
The biggest factor is going to be economics of taking off the annual increment per acre. An annual harvest of .25 to .75 cords (let's take 0.5 for an average) per acre isn't going to pay. And as Tom mentions, not every acre is a productive as the previous. You also have to know at what point do you achieve the 0.5 cord per acre annual increment, when does increment begin to decline. Also, not factored in this is the loss of volume from, disease, aging and decadence. Maybe you should be managing by basal area, crown closure and silvics which can vary by site conditions and species present. Your local Forest extension can give you an idea of your woodlot productivity for the species your growing. Depending on your land holdings, it may be darn near impossible to cover your ground with the intension of taking the annual increment only. It also has a signifiant impact on residual damage and soil compaction. I know folks with 400 acres of woods and they work as much as they can per year, then in 10 years they start all over. They are harvesting volumes of wood economically and sustainably as well as trying to minimize the number of entries. It's more productive and gives more $$ in your pocket. However, if you have just 50 acres and plan on harvesting the annual increment I hope ya have a regular weekly job if your expecting to make a living. For comparison, in my area about 0.4 cord/acre/year is average for 60 year old hardwood, then at 100 years it reached equilibrium, then declines. With uneven-aged management practices the increment can be sustained. If you try to use even-aged, then there is a point where that yield curve peaks, levels off, then crashes.

Two - three cords/acre/year is unrealistic from a 60 year old stand of hardwood in the far NE corner of the US, like Vt, Ma, Me, and NH. Do you think your stand is going to provide 80-120 cord/acre extra at age 100? A 60 year old well stocked hardwood stand probably has between 18-24 cords/acre. Lets look at a 100 year old stand and project it to 140 years, what kind of volumes do you expect? I suspect 40 cords per acre and increasing as you go southward to possibly 60 cords/acre. Up my way, you'd find alot of rot or large heart in a hardwood stand that old.  I've not cruised your hardwoods down there, so I don't know what to expect. Stands I'm relating to are mainly sugar maple, beech, yellow birch, white ash, hemlock and red spruce. The first two species are the main stand component. I know once you get down the lower part of Maine the Oaks become a significant component of your forests.

[SwampDonkey]

Was just looking at the Nova Scotia site index for hardwood and for 22 m (70 foot) well stocked hardwood they expect about 0.58 cord/acre/year and on 30 m (96 foot) hardwood they expect about 0.88 cord/acre/year. We don't have hardwood 30 meters here, if so where? This is at aged 110. ;) For 60 year old 18 m (58 feet) hardwood it's 0.4 cord/acre/year. From what I've researched we are a little more productive in my location than further south in NB.

[whitepine]

I have read  about how much  wood one can get off a stand and also heat with wood totally for over 25 years and sell firewood. One thing I think people forget is when you try to  harvest a dead tree or limb no matter how hard you try you  destroy alot of young seedlings just being in the woods  you damage seedlings and that really  puts the growth rate back. I had always heard one could heat your house on 10 acres (about 7-10 cords up here, NE  Minnesota. I doubt it. Was very interested in nova jack system for that reason.

[Ron Wenrich]

My impression of the growth rate question is for someone taking a harvest of the annual growth rate on an annual basis.  So, the economics is not necessarily a factor. 

As for dead trees, diseased trees, etc., I would assume that they would be part of that annual harvest and would not be lost. 

The Germans have used a system where they use the overstory for sawtimber trees.  The understory, they coppice with ironwood.  This will yield firewood, about every 20 years.  Seems to work for them.

I believe that someone could heat their home on 10 acres, depending on woodlot conditions.  Most woodlots would support this kind of TSI work for a good number of years without touching the crop trees.  When there is an occaisional harvest, then topwood would be used for fuelwood.  Rule-of-thumb  -  one cord of topwood per Mbf of logs.  Also, a 16" tree will yield about 1 cord of wood.

As for seedlings, not every seedling will make it to a polewood tree.  The only time that seedlings have to be considered is when you are looking at reproducing the stand.  Trees put out seeds all the time, but you don't really need them until you are looking at the next forest.  I think we look too hard at reproduction when its not needed, then disregard it when it is.

[crtreedude]

Also, unless you have been doing a good job of keeping the best trees - you are better off getting trees and planting them. If all you have left is the rejects from 3 or 4 high grading, you might not want natural reproduction - unless your goal is misshapen trees.

Here in Costa Rica, high grading is called "Genetic Erosion". 

[SwampDonkey]

I think I understand what Ron is saying. If I understand him correctly, he's not harvesting that 0.5 cord/acre from each acre. It's averaged by practicing sustainable harvesting in a smaller portion of the woodlot and progressing through the woodlot from year to year. Maybe he means something else.  :-\ It's not economical to treat each acre every year for that 0.5 cords/acre. Show me where they're doing it. As far as firewood, 10 acres of well stocked mature hardwood will last about 40 years here, a bit little longer if you need less than 8 cord/year.

[slowzuki]

Burning mostly softwood and white birch at about 4 cords a year, I can't keep up with blow downs etc on 15-20 acres of woods we have.  I can't imagine the growth rate of white birch up to 5" though, must be a high cords per acre.

[SwampDonkey]

Slozuki, your probably looking at 40 year old, 16 meter white birch with an annual increment of 0.68 cords/acre/year. Your only harvesting about a 3rd of the annual growth on 20 acres (13.6 cords/year). If you cut the poorer trees, you'll never have to worry about keeping warm. ;D

[slowzuki]

The sawmill should take care of the big softwoods ;D  The birch we have is about 5 acres on a south facing slope in which all the softwood was removed about 20 years ago releasing the birch.  The birch was then thinned about 8 years ago and has really taken off since then.  It is unique on our property due to the removal of all the softwood.  There is a mix of ash, oak, and what looks to be beech growing below the birch.

Slozuki, your probably looking at 40 year old, 16 meter white birch with an annual increment of 0.68 cords/acre/year. Your only harvesting about a 3rd of the annual growth on 20 acres (13.6 cords/year). If you cut the poorer trees, you'll never have to worry about keeping warm. ;D

[jon12345]

One of the tell tale signs of beech is, a lot of the smaller ones keep their leaves in the winter. 


This 'phenomenon' is called  marcescense  :P

[slowzuki]

Then my suspicions are confirmed, we have some beech!  The largest is maybe 12 ft tall.

[SwampDonkey]

Young sugar maple and oaks do the same. But a beech leaf is pretty distinct and papery, except similar to chestnut. Well... oak, beech and chestnut are in the beech family Fagaceae. I just picked some oak leaves today up on the woodlot. I'de like to scan and convert to line are, by just tracing the edges. Maybe Freehand does this. Have to check.......

[Tom]

Y'all are real lucky to own some Beech front property.  Down here in Florida they are getting some tall dollars for that stuff.   :P : ;D

[SwampDonkey]

Well I found out with Fireworks MX, you can use the flood tool to remove the white background and apply a transparent back ground when exporting the image. This gets rid of that annoying white back ground with images so they take on the color of the layer below. In affect it looks like I have an outline with the texture of the scanned image.  8)



Image has transparent background, the jpg format does not support it. I prefer PNG24 over GIF8 (the number stands for bits of color)

[jon12345]

hey SD nice maple quercus leaf   ;D






:D :D :D

[SwampDonkey]

I need to borrow Paul_H's newspaper, there's this bug that needs smooshed I think.  :-\

[Pullinchips]

I read an article in the Journal of forestry about sustainable woodlot mgt for firewood production.  It said to do it correctly you want to set up some test plots for a cruise and get a base line of volume that is out there today (if you need to know how consult with your local extension office or forestry consultant.  After one year remeasure the same plots with the same trees and see the difference and these numbers after both cruises can be blown up to give you your per acre values that will yeild the total tract volume.  The difference inthe two is the growth that occured in the last year, what ever this number is is what you can sustainibly cut off of that acre in a year.  The trees you want to cut first are not your good crop trees but you want to take out all the disease and newly dead trees the first then followed by poor form trees and then your suppressed trees.  This will allow your good crop trees to grow faster and put on better diameter growth, in the next years.  The last trees that you want to harvest in your rotations are your over mature trees the ones that have the least growth per year.  Once these trees are removed it will allow smaller either codominats to take the place or new trees to replace the one large one. 
The article also gave a chart of cords in certain hight and diameter trees.

This is just a breif summary of the article that i came accross and saved from a year ago.  I am curuios now have to go dig it out of my stuff.

-Nate

[SwampDonkey]

Probably similar to site index curves we have. Shows production at different ages and heights. There are 10 curves I think for New Brunswick. In our mixed forests it's a little science along with some art work. Balsam fir and aspen components  (percent) can significantly influence the production per acre. You can't group aspen in with hardwood and balsam fir grows alot faster than black spruce in girth with similar height growth.

Pullinchips, your method is most accurate for sure without arguement and you develop local volume tables for your stand. In my area we use standard volume tables, but they can be converted to local by taking local measurements. Measure to the nearest  mm or imperial equivalent. I'de do this and average the results over 5 years at least. By then I might be freezing to death. :D :D One thing to note though is the fact that you could probably get your hands on PSP (permanent sample plot) data for your area and go with that, they measure every 5 years here over a broad spectrum of stand types and sites. Our DNR produces FDS (forest dev survey) maps of the forest stands which are all interpreted from aerials and asigned a number. Then the stands for the PSP are taken from those maps/photos. In fact if I know my area, get the photo, it's labled on the bottom with the FDS map to get the stand number. ;D So all you have to do is pull up the data for similar stands over the last 20 years or so and see your growth increment. (or you might luck out and have a PSP in your stand) But, again species composition influences the growth increment, and those plots are only for a plot with a 12 meter radius if I remember correctly.

[Pullinchips]

i thought of the very same thing as i wrote that.  Thinking about usfs and forestry commission permant plot data.

Oh i basically repeated what others said i replied first with out reading all previous posts.