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Thinning Pines

Started by MISDH, April 09, 2007, 03:10:46 PM

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MISDH

We have about 40 acres of Austrian pine we would like to thin to improve deer habitat.  Trees are about 60 feet tall, 10" dbh.  We were told to take every third row, plus every 3rd tree in the remaining rows.  My concern is that it may be too much thinning and may hurt the habitat?  Also, it we thin them as mentioned, will the remaining trees grow to improve the canopy that's left.  It's a phenomenal deer area as it is, and I'm afraid to mess it up, yet at the same time, the trees are beginning to die off.  Anybody have any experience doing this with short and long term results?
Thanks for your input.

Radar67

I just did some clearing on my property lines. Before there was very little sign of deer activity, now there is sign everywhere. My place is thick with underbrush. I've heard some say that thinning will draw the deer in so they can get at the tender tops for browse. I'm sure one of our foresters will address this question shortly.

Stew
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Ron Scott

Yes, that's a common management prescription for a pine plantation to remove a 3rd of the basal area which often equates to removing 1/3 of the volume by removing every 3rd row and "selectively marking" between rows taking the "worst first", mark to leave 90-120 sq. ft basal area.

Leave any hardwood mast trees and den, snag, or cavity trees for wildlife. The thinning will allow for increase growth and crown closure. Also, depending upon the soils, you may get additional pine and hardwood regeneration within the cleared rows.

I assume that you have had a consulting forester or local conservation district forester look at the area to get the best management prescription to meet your objectives. There might be some site specific variations that can be made to maximize the area for wildlife such as making small clearings for wildlife seed and shrub plantings along the cleared rows, interior areas, etc.

Use the entire landscape to your advantage.

I assume that you have a market for the Austrian pine to get the work done through a commercial timber harvest, as this has been most of the problem these days.
~Ron

Ianab

Pine plantations are usually planted much denser than the final crop because the close growing trees make then grow a better form. They grow tall looking for light and drop their lower branches earlier leaving better logs. If some are starting to die then they should probably have been thinned earlier, but you cant help that now.

Rather than strictly taking out every 3rd row you may be better to work with a stems per acre rule and weed out the worst trees from each row. Pick the runts, the ones that are dieing already, the ones with poor form (bent, split, lost tops). Those ones are not going to give you any return in the future, they are just a waste of space at the moment. The trees dont have to be left on any exact grid, as long as the general spacing is reasonably even.

Wether you have a market for the logs isn't really an issue, if the trees are that overcrowded, some need to come out, even if they get thinned to waste. If you can sell them, good, but sometimes the cost of thinning may be more than the value of the logs, especially if you take out the rubbish first.

As for the deer habitat, thinning should improve that, more light gets to the forest floor, means more undergrowth, means more deer food and shelter.

Cheers

Ian
Weekend warrior, Peterson JP test pilot, Dolmar 7900 and Stihl MS310 saws and  the usual collection of power tools :)

MISDH

Thanks for the confidence, I really need to hear that it's the right thing to do.  Here's why I'm so concerned:  I've shot 28 bucks in 22 years within 100 yd radius on this property ("my pines") that was owned by a 92 year old lady.  Somehow, I became the "land supervisor" and when she died, by the grace of God and a partner, we bought 120 acres that hadn't been touched in 80 years.  I'll have more questions on the other 80 acres later.  We do have a market for Austrians, going to Amish for fences, what does $35 per cord sound like?  I have no idea.  I estimate we will remove about 3,500 trees, and I would say that 10-15% are already dead and down.  As near as I can figure they were planted in the late '40's.  Thanks again, and great forum.

Pilot

I always work by what the crowns tell me.  I have rearely, if ever, worked with trees that were in nice, neat rows, and have advocated that planting be done in the best microsites, following a rough, not rigid spacing because a perfect grid gives the problem you describe.  A rigid thinning plan, taking out every third tree for example, pushes you to remove some of the best trees and leave some poorer trees and tells you nothing about what to do where trees have already died.

Crown ratio is the proportion of tree height that has living, green material on it.  A 100 ft. tall tree with 30% of it's height in living crown has a crown ratio of 30%.  Small crown ratios are found where spacing is too tight or in trees that have been overtoped by other, faster growing trees.  Maintaining a spacing that gives crown ratios of 30-40% is ideal.

So, if I were marking your stand, I would mark to maintain about a 40% crown ratio  among the leave trees.  As trees grow, the ratios will get smaller, so 40% is a good place to start, then thin again when they approach 30%.   

I would start by cutting overtopped and suppressed trees, i.e., trees with less than about 30% crown ratio with larger crowned trees nearby.   Areas with ratios between 30 & 40% would be thinned.  Trees with crowns of 40% would be left unless seriously defective for some reason.   In areas where many trees have small (<30%) crowns, I would leave those with the largest crowns. 

Here are some random thoughts/ideas:

Another consideration in your area is what the snow might do to spindly trees.  Snow causes spindly lodgepole pines to go down.  If that is a risk in some areas, then take out all the risky trees and create an opening, which will provide forage.

Are you adjacent to any busy roads?  If so, you might want to create some deer-unfriendly conditions near the roads to reduce the frequency of deer being hit by cars, a big problem in Michigan, I hear.  Talk to some wildlife folks about what kind of habitat deer would be unhappy in near the roads.  For example, good cover near the roads is probably a bad idea.

Wildlife like diversity.  You started with a very uniform, homogeneous, stand.  For wildlife, you want to make it very heterogeneous.  Thinning tends to make stands more uniform over time by opening up areas where stocking is too dense and leaving more open grown trees to grow large enough to compete with one another, which slows their growth.  So in spite of what I said about trying to maintain ratios of 30-40%, you might want to vary that somewhat to create a variety of habitats.  Just be sure to use the 30% as a lower limit.

Richard Scott
Retired Silviculturist



MISDH

We had about 23 deer car hit on out property lines this year.  I want to plant a "barrier" to prevent trespassing, but also keep the deer in.  I think it's an unwinnable battle.

WDH

The prescription you have sounds good.  The 40% crown advice from Pilot is also on the mark.  Taking every third row makes it practical for the logger to access the stand, especially if there is good row integrity.  Thinning will make the habitat much better as it lets light onto the forest floor to encourage the growth of herbaceous plants that deer love to eat.  Don't be afraid to thin the stand.  The trees that you will leave will really appreciate it and the stand health will improve.  You will also significantly improve the wildlife value of the property by allowing good food plants to have a place to grow.  Most people who thin do not thin enough. 
Woodmizer LT40HDD35, John Deere 2155, Kubota M5-111, Kubota L2501, Nyle L53 Dehumidification Kiln, and a passion for all things with leafs, twigs, and bark.  hamsleyhardwood.com

Pilot

A couple other thoughts.

Have you checked the growth rates of surviving trees?  Are they doing well?  Have they slowed down recently?  How about the dead trees in their last few years?  Were they doing OK, then suddenly died?

I am concerned that the spacing sounds fairly uniform, so most of the trees should be in similar circumstances.  If so, your whole stand could be on the way out.  Again, the crowns will tell you the story. 

Are you sure the trees died from competition?  Root disease & bugs might have had a hand.  OTH, if the trees are already stressed from competition, root disease and/or bugs might have finished them off.  If competition, recent dead trees should have small crowns and the lowest live limbs would still have small twigs, just like the uppper crown, so you can estimate crown ratios from that.  Ratios less than 20% put a tree on a death spiral from which they rarely recover.  If much more than 20%, you might want to check for other causes.

You say some of the trees are already down.  Have you checked the roots for decay?

If root disease, you have a problem that needs further evaluation before thinning.

Do Austrian pines generally do well in forest environments in your area?  Offsite trees often have problems in a forest environment.  In a yard they are babied, but in a forest they are on their own and things are a lot tougher. These trees are about 4,000 miles from home; we have seen severe problems in trees planted 200 miles from home, and FWIW, Austrian pines do poorly at 3,000 ft. in western Oregon where winters are mile compared to Michigan.  If your site is different from the seed source (and differences may not be obvious--soil pH or length of growing season for example), your trees might be much more susceptable to bugs & diseases, especially in a dry year, for example.


Ron Scott

Also check the dead or dying trees for excessive porcupine damage.
~Ron

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