Thinning pole pines

[Bro. Noble]

We have a pine plantation that was planted too thick in 1958 and was underthinned due to lack of a market.  We were able to get it thinned about 15 years ago and this past winter,  the small (under 10") were removed.  It now appears to be in fair shape for the time being,  but a utility pole company would like to buy the poles out of it.  A rough estimate is 20-25% of the trees.  I've learned that in our area if you get a good market for pine you'd better consider selling.  The company is reputable and we ,of course, could use the money.  

What I'm finally getting around to is how do you figger basal area?  I've got it in a book,  but no longer read fine print very well.  I don't have a prism,  but remember reading here that you could use your thumb.  My son is available to help me and we can use a tape if necessary.  What kind of range would be desirable for the basal area?  The trees are mostly from 10 to 14" dbh,  with some considerably larger.

Thanks for any suggestions.

[SwampDonkey]

Ron W will probably help you out with the angle guage method. That would be simplest and fastest without a prism. There is still some math involved though.

Distance from the eye to the gauge has to be the same each time you check a tree for "in" or "out", because otherwise that would throw the angle of your view site (guage) off each try. Stand at one fixed point over a broom stick and look at dbh level on your pine tree.

Quite simply, use a string tied through a drill hole in the cross arm sight, usually a rectangular piece of wood. The string is either extended from the neck or held up to the eye with the opposite hand, while the right hand holds the cross arm. You site from the loose end of the string through the wood site, kinda like sighting between a micro foot ball field goal post.

Here is where my math gets a little hazy and Ron can verify whether I'm right. SO don't go out there before you here from Ron or someone using these things.

So if you want a basal area factor of 10 ft²/acre:

Use a string of Length = 33 inches for example where:

 width  = 0.030303 x 33 inches

 so, a 1 inch wide site.

the 0.030303 is the gauge constant for a 10 ft²/ac gauge.

from Basal area factor = 10890 k², 10 = 10890 k², so k = 1/33 or 0.030303.
The big number is how many sq feet in an acre.


gauge constant is 0.030303 for a 10 ft²/acre gauge at 33 inches from the eye.

The info I have is pretty sketchy and no full explanation of the variables used. Crazy things like f_ti f_bi, D_i, or plain old F or D to make your eyes roll.


So each tally tree represents 10 ft²/acre. Note that different string lengths change the gauge constant and site width if you always want a fixed basal area factor of 10 like in this example.

[SwampDonkey]

Link to Michigan Penny angle gauge.

http://michigansaf.org/ForestInfo/MSUElibrary/AngleGaugeUse.PDF

My funky math seems to fit their method. I hope it's right anyway.

 I'm thinking a target of no less than 90 ft²/acre. So 9-10 trees post harvest per plot.

[beenthere]

I have half dozen prisms.  Which one do you want?   

Seems they are marked in "delta" with a number...3, 7, 4, 6..

And they have reference to BA of 16.31, and a number as sq

delta      BA factor
3            9.7
4            16.31
6            39.6
8            64.8

and
7             38 sq
 
Any help which one Bro noble might use, and how?  Been too long for me to recall.
Any help?
I'll send it to him right away. 

[SwampDonkey]

No more complicated than this.



Push a string through the hole, knot it so it doesn't pull out. Knot the other end at the 33 inch mark from the knot tied on the back of the gauge. Hold the knot on the loose end up below the eye with your left and hold the wood piece with the right. Tally (count) trees as wide or wider than the site notch (cut out), by looking at each tree at dbh (4.5 feet above ground). Oh, make sure your eye level is at 4.5 feet above ground and over the broom stick. Maybe you have a walking stick instead to beat the coyotes off. On sloped ground be aware of borderline trees because distance has to be horizontal when checking limiting distance for "in" or "out". That's only if you want to be a stickler. Write it down on a scratch pad for each plot, keep a running tally of the number of plots and counts for each. Easy peasy.

Now why did I say "back of the gauge"? Because I realized that the thickness of the block used will influence the 33 " length from the eye , and as anyone knows looking down a hallway for instance the far end looks narrower because of depth. That narrow end (because of depth perception) is where your gauging tree widths. If your using a real thin gauge it isn't going to make a lot of difference. It's not rocket science accuracy. More to do with consistency.

You can multiply 10 by trees tallied (counted) in a circular sweep divide by the number sample plots, right? Make sure the eye is always directly over the broom handle for each plot you swing 360 degrees as you count "in" trees.

[Radar67]

Push a string through the hole, knot it so it doesn't pull out. Knot the other end at the 26 inch mark from the face of the gauge. Hold the knot up below the eye with your left and hold the wood piece with the right. Tally trees as wide or wider than the site notch. Easy peasy.

Would be if the dimensions were added.  hole size? slot size? block size?

[SwampDonkey]

ONE "1" or won? ...errm inch wide cut out as stated earlier.

[SwampDonkey]

I think Ron W put something in the knowledge base about angle gauges didn't he?

[SwampDonkey]

Any help which one Bro noble might use, and how?  Been too long for me to recall.
Any help?
I'll send it to him right away. 

Any of'm would work, depending on how many trees you want to count. The bigger BAF the less trees. Just multiply those listed BAF's by the average tree count that's the ft²/acre.

[beenthere]

Well, that helps me recall how easy they were to use. Thanks.

And look what I found, by our own Ron.

http://forestry.about.com/library/weekly/aa121398.htm

Good account.

[SwampDonkey]

Ron used a 1:33 ratio for a 10 ft²/acre gauge BAF. Maybe when he comes on he can explain it. So, 1 inch wide gauge cutout with a 33 inch long string.

Never mind, I see here:

Basal Area Factor = 10890 k²

k = 1/33

width of cutout = 0.0303 x 33 inch long string
             = 1 inch wide cutout

Lets fix this mess above.

[SwampDonkey]

There, I cleaned up the math so it makes more sense to me now after studying it out and reading Ron's post in About.com. 

[SwampDonkey]

Check borderline trees of BAF 10 ft²/acre by multiplying tree DBH by 2.75. That's our 1 foot/12 inches divided by the 1/33 gauge constant. It's labeled our limiting distance factor, to see how far away (feet) we can be from the tree, beyond which the tree is out.

[SwampDonkey]

It's pretty much the same math as a prism, only I have never really used an angle gauge.

[Ron Scott]

Thin the pine to 90 square feet basal area (BA) with whatever tool you use to determine the stands current basal area which the foresters are already explaining the use of.

I'm a fan of the 10 factor prism myself for determining BA since it is so light weight and easy to carry to always have available.

The utility pole company will most likely want your largest diameter, tallest, and straightest trees, but again try to work with the "worst first" if they meet the utility's minimum pole specs. Keep improving quality and future valies with this second thinning.

[WDH]

Bro. Noble,

Get yourself a 10 factor prism.  You are worth it .

What kind of pine do you have?  Down here with our southern pines, 90 square feet is too much to leave. 

[SwampDonkey]

  I ain't saying a word. 

[Texas Ranger]

Bro Noble, have the purchasing company mark the stems they want, with no guarantee of sale.  You can prism the stand to death, but if you cannot grade a pole, then the information is worthless.  The poles taken will be high grading the stand, but if the money is right, go with it.

[WDH]

I agree with TR.  At 50 years of age, take the value.  The stand has performed about as good as it will.  After the poles are gone, you can reassess the stand for options.  In my area, poles bring the largest stumpage price of all products by a wide margin.  It is the apex product. 

[Bro. Noble]

Thanks a bunch folks

I've pulled ideas from your posts and an excellent PM from Roxie and have come up with plans for an angle gage and how to use it.  I'm also going to record readings from my thumb from each sample and calculate a baf for my thumb  It should be as accurate as an angle gage for me and anyone else with the same width of thumb and length of arm

WDH,  these are shortleaf pine.  I dug out my 'Manual of Southern Forestry'  and found that it reccomends thinning shortleaf pine at 120-130sq ft. but to leave at least 75 sq ft.  

I plan to see what we have on Sat. and will report back