Marking guide,

[acsa3]

Hi all, I have been out of forestry school for about 6 years and have been working as a contract cruiser.  I am trying to stretch my silviculture muscles so I am writing a management plan for a friend in northern NY.  I used the USDA program NED calculate all my numbers TPA BA and RD, and  now I am trying make a marking guide for a thinning. I know I can use TPA and BA in a stocking guide and thin to the B line.  I am curious, is this how you all are deciding how much to thin? 
I remember in school using a spreadsheet using numbers like the relative density,  mean stand diameter,  and Vbar to make a marking guide but I am kicking myself for not saving it.

[Chuck White]

Welcome to the Forestry Forum, acsa3!

Where abouts are you located?

More info in your profile would be most helpful to the rest of us!  Just sayin'!

[acsa3]

Thanks for the tip, I added a few more details to my profile.   I am located in Syracuse, NY but the property I am working on is in ogdensburg right along the st Lawrence river.

[Ron Wenrich]

First thing to realize is that any time you thin timber, what you leave is a lot more important than what you take.  I've seen many foresters will thin out all the "mature" trees and leave the rest.  Slash for cash method.  The other method is diameter limit cutting where you cut everything that is above a certain diameter.  I call that an economic clearcut.  

The first thing you need to figure out is the reason for the harvest or thinning.  Doing nothing is always a choice.  If the goal is to enhance reproduction, then figure out the best type of thinning for the stand you want to establish.  Shelterwood thinnings are a lot different than seed tree thinnings.  Same goes for uneven aged management where you want to do some small clearcuts scattered throughout the stand.  

I always had a target BA I'd like to leave.  It varies by dominant species.  White pine can have a higher residual BA than a stand of white oak.  If you thin too hard, you may get a lot of epicormic branching.  That is more important in hardwoods.  In pines, you may end up with problems of self pruning, but I never worked in pine stands all that often.  

First things to thin are the poor quality trees.  Its okay to leave some wildlife trees.  But, trees that are crooked or rotten would be the obvious first thing.  The second may be trees of an undesirable species.  This varies widely from site to site.  What would be better to grow in one area, may not be recommended for another.  I wouldn't want to try to grow walnut or cherry on a site that is best suited for pin oak.  

After you get rid of those, then you have to figure out which trees you want as crop trees.  Then you thin to release the crown.  Tree growth mainly comes from crown expansion.  You'll probably be working in the co-dominant class of trees.   I also like diversity whenever I could find it.  Managing for monocultures are always a ticket to bugs or disease wiping you out.

Most stands that I've ever been in have been so badly managed that you can't thin everything out on the first cut.  We have a military base close by my place.  They recently did a thinning in areas that were overgrown fields.  Now that they're done, they look like overgrown fields again, and they're going to have a major brush problem.  

As far as programs go, I never used any of those.  I cruised by using a BA gauge, used a compass and pace method for point location.  I mapped the area as I cruised.  I crunched the numbers and made up my maps and figured my volumes from there.  As I cruised, I would mark which trees I would thin and which I would keep.  In the end, I would have all those values without using some preprogrammed limits.  I always viewed that as cookbook forestry.  

[acsa3]

Thanks for the in depth response Ron.  
  What I am working with is a 27 acre white pine plantation that is visibly overstocked with nothing growing in the understory other than in a couple of small brushy openings.  Basal area is 177 and there are 274 trees per acre.  I found this stocking chart in the silvics manual for white pine, it says it is for pure white pine stands in New England, I imagine it is close enough for what I am doing.  
 


I put the dot on the chart where the current stand is at.  I am a little surprised to see it is below the A line.  I was sure it was packed tight! but i did have a roughly 10% of the points fall in openings with only a couple trees, maybe that is why its a little lower?  
 Anyway The reason I would suggest thinning this stand is simply to open the give more growing space to the residual stand, and favor better quality trees.  
  As far as cookbook forestry goes I think that using stocking charts is a good way to justify to landowners why you are making certain recommendations.  Maybe after a careers worth of experience to pull from it is less necessary, but as a young forester I think you need to back up your decisions with numbers.  

[Ron Wenrich]

There's lots of ways of looking at data.  You're taking an avg dbh for an entire stand and then base the whole management scheme on that stat.  My typical approach is to break down the different sites by timber size and composition.  That would take out those areas with lesser trees, which may have thrown a bias in your numbers.  Those areas may be in a continuous area, but it probably should be treated differently.

Another chart to make for your landowner is the number of trees by diameter class or BA by diameter class.  You should end up with a bell shaped curve in an even aged stand.  Your client will be able to see which trees you're talking about thinning.  You should be removing trees in the bottom half of the curve, unless you have a lot of over mature timber in the upper diameters or you are trying to release decent pole timber.  It gives a better visual for the client.  You can also break it down by species, undesireable vs desirable, etc.  With good data from a cruise, you get a better statistical graphic which can be used in your recommendations.  

The stocking chart is handy for you, and you can address it in your report.  Do you think your client will understand it?  Its been a while since I looked at a stocking chart, but I thought there was an A, B and C level.  A was the minimum of a full stocking, B was optimum, and C was overstocked.  If memory serves me, 180 BA was the max for natural white pine and thinning was no less than 120.  You want to be working within those ranges. I also remember that white pine regenerates in the understory.  You want to establish that before removal of the overstory for a naturally occurring stand.  It all depends on where your stand is currently.

My management plan would end up having the data for the volume in the stand, the volume of my projected thinning, and the costs/benefits.   I have put my cruise data vs my actual removal data to the test, and it comes out pretty close.

I always try to collect as much cruise data as I can.  That's why I map while I go.  I can put in roads, where timber types change, and any natural areas that I run across.  That map always was important to the interpretation of the data.  Each cruise point would have a number.  I then could bunch together each cruise point with timber size and type.  The map would allow me to figure out the area of each timber type.  From there I can go to volumes and stocking levels.  Its always worked pretty good for me.  When I did procurement work, I also would do a preliminary cruise so I could talk accurate numbers with a landowner.

In PA, we have a lot of properties that stretch from the bottom of the mountain to the top.  You have to treat the bottom a lot differently than the top, as the sites are quite different.  That would skew your data if looked at as only one forest type. 

[mike_belben]

Great info ron, thanks for sharing.

[acsa3]

Ron, I like your idea of including a graph of number of trees in each diameter class.  I read the description of the stocking chart for this particular chart it  says the A line is 80% stocking (Fully Stocked) and the B line is the minimum stocking for full site utilization.