what to do for the best results?

[paul case]

here in the edge of the ozarks we have lots of oak. if we dont mow or spray our pastures every year they will take over.

i have a couple places on my ranch that had been neglected before i bought the land and the oaks did just that, took over.  mostly post oak with some white oak, blackjack oak, red oak and bitternut or mockernut hickory mixed in. they are real thick. too thick to ever grow into anything. the way i know is the other place i bought about 10 years ago is the same way except it ws pretty much clear cut by wood cutters when my dad was real young. most of the trees were real close together and only about 12''dbh and 50 to 70 years old.

the question for me is can i help those trees out by thinning them? i would like to cut out some 20' wide strips through the trees, but i dont know if that will cause them to put on a lot of lower limbs and therefore not make as good of logs down the road. i know that they need thinned to grow , but how to do i for the most benefit is my question.   pc

[woodtroll]

How big are they now?
If they are still saplings that may be a little wide.
The other question is how good is the site? Blackjack and post oak are not know for their rapid quality growth.
They are know for growing on dry rough ground, of course the growth rates would be very slow, because it is dry rough ground

[Ron Wenrich]

Stands growing at a basal area of over 110 sq ft per acre is considered over crowded.  Thinning should take you down to 60-70 sq ft per acre.  Basal area is measured using a gauge, which you can buy from Ben Meadows or some other outfit.  Some guys use a prism, which does the same thing, but is more expensive.  The gauge I use is metal and has several different gauges. 

With a BA factor of 10, you would only keep about 7-8 leave trees at any spot that you measure.  Measurement is really simple.  You stand at one point and look at each tree with the gauge.  Those that look bigger than the gauge, you count.  Those that are smaller than the gauge, you don't.  The bigger the tree, the farther away it can be.  You turn a full circle to do the count.  Its really simple.

Your thinning should be a take the worst first type of philosophy.  The worst would be poorly formed trees, poor species (either for the site or for markets), or trees that are in the understory.  You want to keep dominants and co-dominants.  If you stay above the 70 sq ft/acre number, you shouldn't develop any epicormic branching.  Go below and you will risk it. 

Trees only grow when they have room for crown expansion.  When you are looking to release trees, you have to have room for the crown to expand.  Putting in a road will only benefit those next to the road.  If its too open in the canopy, then you risk the epicormic branching and you'll get heavy reproduction on the cleared area. 

[paul case]

thanks for the replies.
the 20' lanes would be so i could mow them with my 15' mower. not so mch for roads.  the trees range from 6'' to 10'' now. some places have been let go a lot longer.

sure enough these places are rough dry terrian.

ron,
i dont understand some of your measurements. i will read and reread your comments and try to figure out what you mean by 70 sq ft/acre and ba factor. however i totally get the take the worst first thinking.  pc

[LeeB]

I would appreciate a little more educating on the subject myself. As hard as I try I just can't make sence of the basal area thing.

[WDH]

Here is a little information about basal area.  Imagine that you had an acre of trees.  Lets suppose that there were 100 trees on that acre.  If you cut every one of those trees leaving a stump exactly 4.5 feet high (breast height), and looking down on the top of the stump, if you measured the cross sectional area of the circle made by the cut top of the stump, you would have "basal area".  To get the measurement, you square the diameter and multiply that by .005454 and the result will be the area of the circle in square fee.  If you did this for each of the 100 trees, and if you added up the cross sectional area of each tree at 4.5 feet above the ground, you would have basal area per acre.

However, it is not practical to cut down all the trees to get a circular stump at 4.5 feet for you to measure, so there are guages and prisms that are made to measure the basal area per acre to make it easy.  

If you had 100 very little trees, the total basal area for that acre would be a smaller number.  If you had really big trees, the total basal area per acre would be much larger.  So, over time, foresters developed a scale that determined how healthy and well stocked a timber stand was based on basal area per acre.  It has been found that for a stand to flourish and grow at an optimal rate, the basal area should be about 70 to 80 square feet.  If it is a whole lot lower than that, there are not enough trees or the trees are understocked for the potential of the acre.  It is like eliminating every other row of corn in a corn field.  That will reduce the yield and the potential of the acre to produce the most corn.

If the basal area is too high, the trees are too crowded and there is not enough sunlight available for the crowns of each tree to maximize the sunlight and growth.  The growth on the individual trees slows down, and they will not reach their optimal size in the shortest period of time.  So foresters manipulate the basal area which manipulates the desired stocking of trees to give each of the individual crop trees the best chance to grow into an optimal sawlog.

By measuring the basal area of your stand, you can determine if the stand is well stocked, understocked, or overstocked.  If you measured the diameter of each tree on an acre and if you used that diameter to calculate a basal area for each tree and added them up, you have basal area per acre.  Or, you can buy a 10-factor prism.  It is a wedged shaped piece of glass.  For every tree that fits the measurement criteria of the prism, that represents 10 square feet of basal area and you do not have to go running around and measuring a whack of trees with a diameter tape.  You simply turn in a circle and look at every tree in view with the prism and determine if it is "in" or "out" of the sample.  Count the number of "in" trees, lets say there are 7 identified by the prism as "in", then you multiply by 10 (remember this is a 10-factor prism), and you get 70 square feet.  So the spot you are standing in has a tree density of 70 square feet of basal area.  If you do this in a systematic way across the property by putting in "sample plots" you then can see the average for the property and where the basal area may be high or low.  This is called a "timber cruise".  You can also measure the diameter and height of the "in" trees identified by the prism and get an estimate of the volume of wood that you have.  

[mrcaptainbob]

What an education I just received! WOW! Thanks for this thread....

[LeeB]

Thanks. I think I understand a little better now. If you used a gauge like Ron talked about,
With a BA factor of 10, you would only keep about 7-8 leave trees at any spot that you measure.  Measurement is really simple.  You stand at one point and look at each tree with the gauge.  Those that look bigger than the gauge, you count.  Those that are smaller than the gauge, you don't.  The bigger the tree, the farther away it can be.  You turn a full circle to do the count.  Its really simple
how do you then determine the  area you have surveyed?

[BaldBob]

You don't determine the area you surveyed.  You are simply taking a sample. To calculate how many trees to leave/acre, determine the average diameter of the best trees you want to leave. If for instance that is 8.5" dbh, each tree has a basal area of 0.394 sq.ft ( {4.25x4.25 x3.1416}/144). So to leave 70-80 sq. ft. of basal area, you would need to leave 177- 203  8.5"ave dia. trees/ ac. That is an average spacing of about 15' (43560/190 =229 1/4 sq. ft of space /tree). You would first thin a sample area to roughly that spacing and then check with your angle gauge to see if you are leaving the desired basal area. If you are leaving too many trees cut some more and check it again. If you have left too few, move to an adjacent area and thin it leaving a few more trees, and check it. Once you have it "dialed in" i.e. you have an "eye" for what it should look like you can start thinning in earnest and only need to check with the gauge every so often.  

[SwampDonkey]

Couple older threads.

https://forestryforum.com/board/index.php/topic,16165.0.html

https://forestryforum.com/board/index.php/topic,26821.0.html

You can also use a circular plot which can be set up with, say a radius of 30 feet. Establish this with a logger's tape by measuring out from a central point along the north, south, east and west axis. Tie a ribbon to mark the extent of the 30 feet in each direction. When sampling envision that your inside a circle, and interpret the arcs of the circle between the ribbons on the perimeter. This method takes longer to sample your woods, but eliminates prisms and gauges. The math is also a little different because it is based on your plot area and not limiting distance (tree diameter). It seems complicated, but it's really just more measuring involved.

[Ron Wenrich]

Here's a couple of articles I wrote for here and another site.  Its found in the Knowledge Base:

https://forestryforum.com/cgi-bin/tips/tips.cgi?display:1010359123-3833.txt

https://forestryforum.com/cgi-bin/tips/tips.cgi?display:1010359141-3837.txt

https://forestryforum.com/cgi-bin/tips/tips.cgi?display:1010359154-3844.txt

What you are doing is called point sampling.  Its based on a sampling technique.  I have used the technique to do everything from cruising timber to on site managing.  Once you learn the technique, you'll find that forest management isn't as daunting.  In my opinion, its one of the most basic skills that someone in the industry should have.  Unfortunately, that is most commonly not the case.

I have written management plans and performed cruises using these methods.  All the equipment I needed was a diameter tape, a BA factor gauge, a compass, and writing material. 

[WDH]

I recently thinned one of my pine plantations and I left a residual stand of 175 trees per acre.  I left that number because the stand had an average diameter of 8.25".  Square that (8.25*8.25) and multiply by .005454 and you get .371 square feet for the average tree.  .371 square feet times 175 trees = 65 square feet per acre.  That was my target stocking.

[LeeB]

The light gets a little brighter. Thanks guys. :P

[BaldBob]

If all the formulas and mathematics and theory of point sampling gets a little daunting, you can get pretty good results from most thinnings by simply following the D+4 rule of thumb : pick the average diameter (in inches)at which you want to make your next cutting entry into the stand, add 4 to that number and the resulting number is the average spacing (in feet) you should thin to.
Remember that is an average spacing.  If for instance the spacing desired calculates to 16feet, but 3 very good future crop trees (species, form, & growth potential) are within 8 feet of each other, but its 25feet to the next good future crop tree, that's fine.

[Ron Wenrich]

How does that number work in hardwood stands?   Hardwoods are generally at a random spacing where many softwoods are planted.  Softwood crowns are much more compact then those of hardwoods.  That makes the thinning and the residuals just a little harder than saying x amount of feet.  At least, that's been my experience.

Another factor may be if you're trying to practice even aged or uneven aged management. 

[Banjo picker]

Great thread guys...thanks a bunch....Tim

[WDH]

I have found that in pine, the number of trees/acre is the key, like BaldBob implies, and the perfect spacing is less important.  I am not sure if this applies to hardwoods in the NE.

[caveman]

Paul, This may help in determining basal area.  A 1/10 acre plot has a radius of 37'4" and a 1/20 acre plot has a radius of 26'3".  You could choose a spot that is representative of your forest and measure the basal area of the trees in your sample plot, then measure by the denominator (10 or 20) to estimate your basal area per acre.

I understand you are managing for hardwoods but a publication put out by the Florida Forest Service suggests a few rules of thumb to go by when determining whether or not to thin SYP's...
1.  If the live crown ratio is above 33%
2.  If the annual rings are closer together than in the past
3.  If the basal area exceeds 120 ft2 per acre

I have also seen some foresters who use a coin (I don't remember if it was a penny or a nickel) as a gauge to determine which trees to count.  They would count the ones that extended outside of the coin when held at arm's length, measure the basal area of the counted trees and convert to a basal area per acre figure. 
Caveman

[BaldBob]

Ron:
Though I have never worked with Northeastern Hardwoods, most of my active forestry career was in the Northern Rockies where random natural spacing was the norm, and many stands that I worked with were managed on an uneven-aged basis. For many of the conifers that I worked with, a D+2 rule was more appropriate. The D+4 rule that I put forward will, in most stands, put your basal area in the range I see most often cited for Northern Hardwood poles/saplings.  Remember the spacing you are shooting for is an average not a hard and fast rule to be applied to each tree.

In stands that are already uneven aged with a large spread of diameters in the trees to be left, a better approach for Northern Hardwoods might be to simply space the leave trees out to leave at least 3-5' between crowns on at least 2 sides of each tree left - leaving only the best trees regardless of size.  Both that approach and the D+ rules are much easier for someone who has trouble understanding how to use  basal area, or how to calculate an appropriate "J" curve for a truly uneven aged stand, to apply. I won't even try to get into explaining how to manage an uneven aged stand in which both tolerant and intolerant species are wanted to be kept in the stand - which was often the case on many of the stands on the ownership I managed.

When I talk about uneven-aged stands, I am referring to fairly homogeneous truly uneven-aged stands. A parcel that has a bunch of even aged patches of various ages - even if the patches are as small as 1/4 acre - may be regulated on an uneven aged basis for the parcel as a whole, but silviculturally, each patch should be managed on an even-aged basis.  And each patch will have spacing needs based on the size and age of the trees in that patch.

[SwampDonkey]

Even aged forest grown sugar maple grows quite tight actually with narrow crowns, the wide spreading maples are those that become mature and have gained competitive advantage suppressing their neighbors. Beech can grow a much wider crown in mixed hardwoods, but not in pure stands until again some get that competitive advantage over others. Yellow birch will not survive unless it shoots above the maple and beech and spreads it's crown. I suspect oaks will not do very well for long in thicker stands. Hickory would like beech. Up here maple and beech in tight spacing, immature-mature will look like they are frozen in time for diameter growth until they get a good thinning. You can go on crown land in maple stands that have never been harvested and the biggest tree might be 20 inches and the odd one 40+ inches, but the average will be around 8". Those are stands that no one intervened. There is no undergrowth, like a park. Hardly even a hazel nut bush. If you do find any significant amount of shrubs it usually means the softwood all died off creating holes. Hobblebush,mountain maple, beaked hazel and stripe maple are usually the predominant shrubs if stocking is low.

[Ron Wenrich]

Bob

I agree with your management of uneven aged stands.  That's how most stands are managed here in the east.  Essentially, its all even aged management, just that your size of stand is a lot smaller.  Then you blend it together to get a representative of all diameter classes.  The classic "J" curve is pretty hard to accomplish with most types of private ownership. 

The way I use thinning is to use a BA gauge and to look up.  The gauge tells me the stocking level, the crowns tell me which trees need thinned.  Sounds like we all do it pretty much the same way.

For those still playing along, a BA gauge of 10 can be made with the ratio of 1:33.  A 1" target at the end of 33" will give you a BA factor of 10.  If you have a quarter and your arm is 33", then you're in luck.  Point sampling makes it that you don't have to measure plot size.  If the tree is larger than the target, you count it.  If its smaller, you don't. 

[WDH]

A small tree may be "out" and not counted at 20 feet from your sampling center point, but a very large tree can be "in" at 50 even 100 feet or more.  The larger the diameter, the farther it can be away and still be "in" the sample. 

This is very different from a fixed radius plot where all trees are counted within the confines of the plot.

[paul case]

i am going to have to study your methods some more. some of the things you guys are talking so deeply about gets way over my head. i think i get the whole jist of it though. make some room for the trees to grow by taking some out but dont take out so many that a lot of light gets to the ground. spread the stand out if possible and leave desireable species and type.
however i have been working close to these woods lately and noticed that i didnt mention there are some big wolf trees. some will be a little big to saw. i dont like to saw over 32'' and some of those will have a but cut of 40'' or more. the crown of those trees takes up a lot of room. i will probably take some of those out when i thin these woods since they are really too big already.  pc

[Ron Wenrich]

Big wolf trees can be girdled and killed if you don't want to fool with the wood.  They make good den trees.

The BA thing is just something that you can do as you thin to see if you've taken enough or have taken too much. 

[SwampDonkey]

Often times the harvesting is dictated by the species presented to you. If for instance you're in a hardwood stand that is familiar to us in NB you may be met with a different approach. If your stand is predominately maple with beech as a lesser component, it's best to create small patches or your understory will be overrun by beech if the crown closer overhead is too tight to allow the maple regen to grow. The maple will live in shade, but that's about it. Once the beech seeds in the maple regen is choked out. We had a hardwood course one time and a guy from NY was trying to apply what they do to here. The beech down there apparently suckers a lot off roots. Not up here, he found out right quick that all them seedlings he pulled up was from seeds. Also our hardwood don't put on 4" every ten years, it's closer to 20. Beech is like balsam fir, it is very shade tolerant and will take over when everything else is shaded out. Another to include in that is ironwood (O. virginiana). I have seen sugar bush be over run by ironwood undergrowth when doing light thinning as well.

I have a photo in my gallery of beech that has over run my uncle's firewood lot. Slow light thinning over years, does it every time. The same happened to another lot he and grandfather cut firewood from for years. Thick beech undergrowth, overstory of sugar maple.