Tables for Volume of Timber

Gary_C · April 12, 2009, 12:10:49 PM

What tables or programs are there for estimating volumes of timber in cords?

I have a booklet from USFS with tables for board feet and have looked in the toolbox and there is a good calculator for bd ft there also, but nothing for cords.

Here is what I am looking at right now. I would like to know approximately how many trees I would harvest from this stand :

White Pine - 18" avg dia, 6 stick avg. Approx cords - 35
Norway Pine - 13" avg dia, 5-6 stick avg. Approx cords - 40
Avg basal area = 150^2/acre

Second stand:

White Pine - 12" avg dia, 4 stick avg Cords - 65
Norway Pine - 10" avg dia, 3 stick avg Cords 30
Avg basal area = 160ft^2/acre

The stick reference is for 100 inch or eight feet logs.
I assume the numbers are based on a 3 inch min top dia.

In addition to number of trees of each species and stand, it would be nice to know what top diameters for 16 foot logs would come from that white pine.

Also I would be thinning both stands to 90-100 sq ft/acre.

Tell me how I would calculate those numbers.

SwampDonkey · April 12, 2009, 07:55:46 PM

Gary, take this for what it is. Our NB white pine is around 75 feet @ 18" dbh, red/Norway 60 feet @13", WP 65 feet @ 12", RP 56 feet @ 10" dbh, total heights forest grown. I think you could knock off 10 feet for the tops.

My estimates here are for 4" tops from sites that are better than average for growth in NB.

Stand #1

white pine 18" would take 57 trees for 35 cords. (0.615 cord/tree)

red pine 13" would take 135 trees for 40 cords. (0.295 cord/tree)

Stand #2

white pine 12" would take 317 trees for 65 cords (0.205 cord/tree)
red pine 10" would take 188 trees for 30 cord ( 0.16 cord/tree)

Some figures to mull over anyway. 2 cord per thousand if you want to convert off board footages.

Those figures are from volume equations where you use diameter to calculate merchantable volumes, taper and height is built into the equation based on site and dominance.

If you want to find basal area, use a 10 ft²/acre angle gauge. It's 1:33 for the ratio. For instance, a 1" wide site uses a 33" string from the gauge to the eye. Each tree over a point (stick in the ground , gauge held at 4.5 feet high, looking at tree at same height) counted as "in" covers the gauge site and represents 10 ft²/acre. After harvest you should see 9-10 trees per circular sweep on average, but may vary from 8-12 maybe, won't be perfect.

Can't help you on the upper diameter of 16 foot logs on a standing tree. Need a little pricey gadget for that. ;)

Gary_C · April 12, 2009, 11:03:19 PM

Thanks for the numbers. But now how did you arrive at those numbers? Are you saying you use the board foot volume tables and use 2 cords per thousand to convert?

I just reread the USFS handbook and it says this about top diameter of the first log.

"On standing trees, measurements of diameter at the top of the first log may be secured by climbing or by the use of a light sectional ladder. Two centers and one base section of a window cleaners ladder are recommended."

Is this the pricy gadget you are refering to? ;D

SwampDonkey · April 13, 2009, 04:40:09 AM

I used m³ standard volume tables (equations). ;D and converted to 8' softwood with:

1 m³ = 0.41 cords ;)

We have to use cords here around loggers and woodlot owners because m³ and board feet are foreign languages, or I assume hard of hearing because you get a lot of "What?!". :D

SwampDonkey · April 13, 2009, 06:42:22 AM

Well here is the cheapie but complicated math approach without climbing, other than out of the machine cab. ;D :D

As far as upper diameter on a standing tree, you could use your 10 ft²/acre angle gauge, a percent scale clinometer and a tape measure. Make sure your across slope (same contour) or on the level to do this, because it's easier to determine the 16 foot mark on the tree. And your angle gauge's constant K becomes variable as the length of your string changes so that the upper diameter just fits your angle gauge site. You'll also have to correct the slope distance from your eye to the gauge as your holding it on a 45 degree slope. ;)

Determine the height your eye is above ground, mine is 5.8 feet for instance. So, 16 feet minus 5.8 feet leaves 10.2, and add 1 foot for stump height, so your actually looking 17 feet up the tree and standing 11.2 feet away from the trunk. And remember that the distance from the tree is in relation to the angle gauge, not the eye. This 11.2 feet is now the Limiting Distance. This horizontal measurement should be taken from the side of the tree to approximate the pith position in the tree. Not the face of the tree in relation to your position of observation you'll be estimating the upper diameter at. So, in our example, measure out 11.2 feet on the level. You can't be up or down hill from the tree, your feet should be at the same elevation as the tree base. If not it adds another variable to the math and that influences how far you stand away from the tree each time. This means you would need to calculate the slope distance each time to determine how far from the tree gives you 11.2 feet horizontal. Your slope angle is from your position to the 5.8 mark on the tree, eye level to eye level. In cruising the reference point is usually at the 4.5 feet mark where DBH is measured, just so you know. It's easier to use eye level for this exercise and you can mark the tree with a piece of flagging tape or a paint line when you stand up next to it.

For reference:

Horizontal distance = COS (θ) x Slope distance

So,

Slope distance = Horizontal distance / COS (θ)

To convert the clinometer percent scale to an angle it's:

Tan^-1(percent reading)
100

On your computer open your "Calculator" program. It's under the Start button and Accessories. As an example use 100 percent. So, 100 divide by 100 is 1 obviously. Punch in 1, hit the "INV" check box and then hit the "tan" button. You get 45 degrees.

Getting back to the task at hand, lets work on level ground for now. ;)

So, at eye level you need to stand 11.2 feet away from the tree, measured from the side. Again, the distance from the tree is in relation to the angle gauge and clinometer, not the eye. We'll call this our Limiting Distance as stated earlier. Now take out the clinometer and sight on the tree. Travel up or down the tree so your clinometer reading is 100 %. ;) Note where that hits the tree. Now dig out the angle gauge with it's string. Hold the gauge at that top position sighted with the clinometer (11.2 feet away) and move away or toward the gauge (gauge is at stationary horizontal distance , but you have the squat down) with the string lengthened or shortened and held to the eye until the tree diameter up there just hits inside the site. A stick drove into the ground with the gauge held at eye level resting on the stick helps here. Kind of like a circus for a bit here. ;D The edges of the tree trunk should just tough the left and right edge of the gauge. Now measure the length of string that satisfies the previous description and correct it's slope, knowing that the angle is 45 degrees. This will be horizontal length of your string. Note it.

Lets say your gauge site is 0.6 " wide. Then let's say the slope distance of the string was 12.5" long.

Horizontal distance = COS (θ) x Slope distance
= COS (45) x 12.5"
= 8.8" string

Now find new gauge constant K

K = 0.6" site width / 8.8" string length
K = 0.06818

Now find diameter up at 16 feet.

Diameter= Limiting Distance x 12 in/foot x K
= 11.2 feet x 12 in/foot x 0.06818
= 9.16 inches top diameter of first 16' log

Well you wanted it, it ain't pretty. :D :D

Now, wouldn't ya like to have a little gadget to point and click and read the diameter up there? It could get real interesting if your trees are small and trying to find that diameter if your arm or string is too short to site the upper trunk within that gauge site. ;D :D But you don't even need your gauge, you could use a small stick, measure it's width where you tie the string at and measure the string slope distance to your eye to find K. Line of sight would be along that string with the tied knot at the top of the gauge height stick and in squatting position to line up with the upper diameter position on the tree. Make sure the trunk just fits the width of your small stick your using for a substituted gauge. Don't forget to slope correct the string's slope distance. ;)

We need a sketch here:

An optical caliper would be nice to have in the tool kit or a fixed-angle range finder dendrometer. ;D

SwampDonkey · April 13, 2009, 09:43:15 AM

I did a yard poplar tree and for my example I did an upper diameter for 21.8 feet from the tree base, limiting distance is 17 feet.

DBH was 19.68 inches at 4.5 feet

For a gauge I used the width of my finger, which was 0.59 inches. Slope distance of string was 14.17 inches.

slope correction on the string was 10.02 inches

gauge constant K = 0.59/10.02 = 0.05888

Upper diameter at 21.8 feet was

Diameter = 17 feet x 12 in/foot x 0.05888
= 12 inches outside bark

Ron Scott · April 13, 2009, 11:44:36 AM

Gary,

Will this help? Note the cordwood tables here.

http://learningstore.uwex.edu/pdf/G3332.pdf

Gary_C · April 13, 2009, 01:27:08 PM

Ron,

Yes, that looks like a good table on cordwood. I am surprised that these tables do not take the Form Class into consideration, but they will sure be close enough for my estimates.

I am also a little surprised there are not more good tables for this. Perhaps the local agencys like the MN DNR have their own tables for different areas that the foresters bring back their diameter and height data from their cruises and along with tree numbers they determine cord wood estimates.

What I am doing is looking for some red pine pulp and these trees will be sold as pulp and bolts. When I see those 6 stick, 18" diameter White Pine trees, I am thinking there may be some better use for those trees than pulp, but the markets for pine bolts are not at all good right now. Perhaps they would be good for some cabin logs but that market may not be very good either?

SwampDonkey · April 13, 2009, 01:42:58 PM

The cabin or log home market here has been hit and miss. One outfit went down 3 times and the other looks like a hobbyist play thing. This isn't cottage country like some regions are and most will build them from their own material either on site or the woodlot. That could be a lot different some place else if people don't have the means or gumption.

Ron Wenrich · April 14, 2009, 04:47:51 PM

For volume per tree, you can use a handy calculator over at a renegade site called timberbuyer.net. :D

http://www.timberbuyer.net/pulp.htm

Output can be in cords, tons, cubic feet, metric tons or cubic meters. Stick length can be 4', 5', or 8'.

SwampDonkey · April 14, 2009, 04:54:59 PM

Seems to be broken Ron, unless I'm doing something wrong.

Renegades :D :D

Gary_C · April 14, 2009, 05:04:51 PM

Worked for me, so it must be you, the renegade. ;D

SwampDonkey · April 14, 2009, 05:23:48 PM

Well, your one up on me. ;D :D I can't get it to work. :

A 15" balsam fir should be 1 m³, I was curious about the numbers. They top out around 68 feet. It's just a bench mark volume we go by here.

Ron Wenrich · April 14, 2009, 07:55:17 PM

Yes, it does seem to be broken. Well, it used to work. :D

Maybe I'll have to get back into the program and see where things went wrong. Do you think the new Java has anything to do with it?