Epicormoc sprout control

[maple man]

I have a fifty acre mixed wood lot in central ME which was abused in a variety of ways before I bought it ranging from neglect of reforesting pasture to severe high grading of existing stock. I have been releasing and pruning oaks and maples for about 12 years with good results but last year had 10 acres mechanically harvested in patches from 1 to 2 acres removing everything but selected crop trees which are spaced out and exposed. My previously released crop trees (10"-16") are looking great but many of the the smaller trees (4"-6") are now sprouting vigorously and I am, as expected, going to be scraping off the epicormics while they get used to their new situation. This is a hobby lot so the time spent isn't an economic issue but lots to do and I want to use it to best advantage. 

Questions:
   How large can these sprouts be allowed to grow before they degrade the log quality? 1/8 inch? 1/4 inch?
    Does time of year they are pruned off influence how quick they grow back or how fast  the tree catches on that they are not needed?

I am hoping that these trees will stop sprouting once the crowns expand but will this tend to continue until crown closure improves to shade the bolls or just until the tree develops a healthier crown size?

Thanks for your help

[Ron Wenrich]

The epicormic branch has already made the defect.  On the smaller trees, they may contained in the low grade cant during the sawing process.  The larger trees will yield some defect in some of the jacket boards.  If you're lucky, it stays only on one side of the board.  The grade on the board will drop.  I've sawn through logs where the grade drops dramatically, then comes back up on the next pass.  It was due to epicormic branching.

Epicormic buds are under the bark of most trees, and they branch out when stimulated by sunlight.  That generally happens when your residual stand stocking is too low.  

When I was marking timber, we liked to leave the residual stand at a stocking level around 60 sq ft of basal area per acre for hardwoods.  That was sufficient to keep the epicormic branching to a minimum.  In most cases, we could get a bit of regeneration., but that wasn't the purpose of the thinning.  Basal area is measured by using either a prism or an angle gauge.  I've used the angle gauge because they are cheap, easy to use, and indestructible.  Its simple and involves point sampling.  You simply use the gauge to get a quick idea of the basal area you have in the stand before cutting, and then after cutting.  

Best way to do it if you have lots of undesirable species is to do it in several intervals.  Thin back to about 60 BA, then wait a few years for some growth and thin again.

If you're looking at regeneration, you want to remove all the understory trees, especially of undesirable species.  Then, after regeneration, remove the overstory.  

[maple man]

Ron Thanks for taking the time to answer my questions.

I may be trying to accomplish too many goals at one time The primary goals here were to get rid of a decaying fir stand and regenerate desirable hardwoods. Also to complete the release of crop trees which had been partially released all ready and were completely dominant and are still growing well. The trees in question are the smaller crowned hardwoods that were struggling but are tall and straight and will make good crop trees if they can be kept from branching. My thoughts are to try to keep the sprouting inside the central cant and to minimize any defects by keeping them contained within a single year ring. I guess my biggest question is whether these trees will eventually stop putting out the sprouts over several years or will be likely to sprout until the canopy starts to close which will be quite a few years.
One of the problems of dealing with such a small lot is that just to get to a harvest volume that justifies bringing in the machines means either cutting more acres than I want to do at one time or to cut heavily in the areas I am having done.  I may have to accept that keeping the desired basal area and cutting more of the lot is the best way to go.

Thanks again for your comments