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Shelterwood Cut

Started by Gary_C, September 08, 2008, 01:58:12 AM

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Gary_C

I was just reading in the GLTPA publication about the three types of timber harvest practices. The column was written by Bill Cook, MSU Ext Forester and it reminded me of a question I have.

First timber harvest practice is the clearcut and that is obvious how that works. Another is called a thinning or selection harvesting and I think I understand how that works. However the third method mentioned is a shelterwood cut and though I have heard of it I do not know just what a shelterwood cut really is and how it is done. The only explanation offered was that it was somewhere between the other two methods.

So what exactly is a shelterwood cut?  How is it done, and how does it differ from what is known as a selection or thinning cut?
Never take life seriously. Nobody gets out alive anyway.

underdog

Like i thought http://raystown.nab.usace.army.mil/LandManagement/shelterwoodcut.htm
A:Clear cut leaves some mature trees -
B: later they call those left shelterwood and cut them so the little ones can get more sun
C: then they do the thinning
D: start back at A agian
Wonder how maney years it takes to make one cycle?  50yrs ?

SwampDonkey

Shelterwood leaves seed trees for areas that regeneration is inadequate, once established those leave trees are harvested. Basically a two stage clear-cut. Mostly practiced here with tolerant hardwoods where you try to remove the beech, softwood and lesser quality maple and birch and space out the leave trees to seed sugar maple and yellow birch. A lot of the times a strip clear-cut method is used instead, not really a shelterwood. A shelterwood could be used to reduce sun scald of young seedlings being released as well until these adjust with new 'sun' leaves.
"No amount of belief makes something a fact." James Randi

1 Thessalonians 5:21

2020 Polaris Ranger 570 to forward firewood, Husqvarna 555 XT Pro, Stihl FS560 clearing saw and continuously thinning my ground, on the side. Grow them trees. (((o)))

tonich

There is one significant difference, though:

With clearcut the stand changes in one stage, immediately.
In shelterwood it takes usually about 20-40 years to introduce the new tree stand. The more shade tolerant are the species, the more time it takes for the stand to turnover. By shelterwood  we slightly replace mature trees by seedlings, ending up with a second-growth stand.
It can be done in up to 4 stages:
-   Preparatory felling = shelterwood thinning = final thinning
-   Regeneration felling
-   Secondary/Increment felling
-   Final felling
Often in practice stages are less than 4, even combining 2 in 1.

As it happens, both approaches lead to similar results, regarding time consumption.

Still, shelterwood can successfully handle both light demanding and shade tolerate species, while clearcut is more suitable for light demanding trees species.

WDH

The shelterwood is a regeneration cut designed to do two things:

1).  Leave a stand of desirable species to regenerate the future stand
2).  Leave enough volume to allow for a second harvest to remove the shelterwood when the regeneration is established.

It differs from a seed tree cut in that you leave more trees as a seed source to better guarantee regeneration, it produces more shade to protect the new seedlings (oak needs partial shade to naturally regenerate for example), and there is enough volume to allow for a merchantable harvest of the seed source once the leave trees have done their job.

It was used extensively in naturally regenerating southern pine before there was so much artificial regeneration (planting either mechanically or by hand to regenerate the site).
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

Lanier_Lurker

Yep, I learned the hard way about oak and hickory seedlings needing some (if not majority) shade during their first few years.  They cannot tolerate full sun, or at least don't tolerate it very well.

Persimmon seedlings seem less bothered by full sun, which may be a reason that they emerge so strongly after clear cutting in some areas of the southeast.

Black_Bear

Also, group selection or single tree selection is generally associated with the management of uneven-aged stands. Shelterwood cuts, along with clearcutting and seed tree methods, are generally associated with even-aged stand management.

In Maine the shelterwood method is often used to reproduce eastern white pine (WP). Although the stand may contain different species interspersed throughout I am thinking of the white pine-hemlock or white pine-red oak-red maple type. The first entry will leave a residual stand of healthy pine somewhere in the 40-80 SQ.FT./Acre (BA) range. The residual BA will depend on the original stocking and desired objectives and can vary from stand to stand.

The shelterwood method serves a few purposes when trying to promote a new stand of pine. First, the residual trees can provide an excellent seed source, which can be an important factor when trying to regenerate WP. Not just the presence of seed, but a great abundance of seed is often imperative when trying to successfully regenerate WP.

Second, the residual trees provide some shade to the seedlings. This method has been shown to reduce the amount of weevil attack among the young trees; the weevil appears to prefer trees that have leaders completely exposed to sunlight. If the saplings are mostly shaded then the weevil will tend to reside in the larger tree tops, thus sparing the young trees from girdling and subsequent crooked growth within the future log wood.

Third, the space given to the residual trees by the removal of other dominant and codominant trees allows for potential release and/or steady growth until the final cut occurs. Often, crowded stands will stagnate and the growth rates will slow as the trees age. Removing a portion of the stand using the shelterwood method may not increase growth rate (release), but generally allows for the residual trees to grow at a steady rate instead of a declining rate. After "X" amount of years when the understory has become well established the residual stand remaining from the first entry is harvested in what amounts to an overstory removal. The "well established" stage in Maine is generally after the new tree has reached at least one clear 16' log in height. If the weevil attacks the young trees after this point then the tree may have a crooked top, but will still retain log material. Also, the young tree will tend to release after the overstory has been removed and the intermediate shade-tolerant WP hopefully will benefit from the increased sunlight .

You can probably already tell that the second (or third entry, depending on original stocking of the stand) entry could be an operations nightmare. Trying to walk the feller or skidder to the residual trees without damaging the regeneration becomes a challenge or near impossible. Group shelterwoods or strip cuts will sometimes be used to eliminate the operations nightmare during the overstory removal. The objective here is to leave groups of trees or strips of trees and then thin between the residual groups or strips. The resulting stand will be composed of islands or strips of mature trees and the regeneration can mostly be avoided during the overstory removal.  

Gary_C

Thanks for the replies. I think I understand the difference now.

If I understand this right, after you decide it is time to start over, then you decide on either a clearcut or shelterwood based on the light needs of the regeneration species.


One more question. If you approach a mature stand for cutting, how do you know if the stand needs another thinning or is ready for a final cut? In other words, how do you determine if this is the time to remove all the mature trees on either a clearcut or shelterwood cut?


Never take life seriously. Nobody gets out alive anyway.

tonich

The main goal of this particular cutting is regeneration.
The actual decision is being taken upon the stage/speed/pattern oft the regeneration process and seedlings coverage. Having enough undergrowth established is a good reason for acting. Here in Bulgaria, for the local oaks we consider 30000 seedlings per hectare an excellent undergrowth. 20000 are still affordable. About 15000 should be OK for the Common beach, 10000 for the Silver fir and over 20000 for the Scots pine. This is where usually start from with the Secondary/Increment felling (stage 3 from the given above), which main goal is to train the seedlings and give them a chance in the competition with shoots and undesired bushes.
If the number of seedling is much less, roll back to stage 2 (Regeneration felling).
If the crowns’ canopy is too high and space is not enough for the sunlight to reach the soil, go back to stage 1 and do thinning, reducing the canopy class.

The final cutting is just done when more of the future stand is well established. It depends on the biology and ecology of the particular tree species. Black_Bear has been given an example for the Eastern White Pine in Maine.
Than again, the more light demanding are the species, the faster releasing they will need.

WDH

Quote from: Gary_C on September 09, 2008, 01:14:32 AM
One more question. If you approach a mature stand for cutting, how do you know if the stand needs another thinning or is ready for a final cut? In other words, how do you determine if this is the time to remove all the mature trees on either a clearcut or shelterwood cut?

I try to think about your question economically.  When the stand reaches a certain age, say 40 years in Southern Pine, the trees are mature, and the growth has slowed considerably.  Any mortality at that point can offset any growth, and the stand is static at best.  It is like money standing on the stump making 0% interest.  You would be better to take the money, put it in a CD, and start over with a vigorously growing new stand. 

When the primary product has been grown, sawlogs for instance, you have achieved the stand potential product value.  From that point on, it is about managing the $ unless you place more value on the "woods", "recreation", or "wildlife".  If those factors do not override the management of the $, then think about the net growth in the same way as an interest rate on the standing money.

It is not always simple, as we all know.  When is the final product value achieved?  In most cases, it is sawlog size.  When you get solidly to the size that commands  the best price, you are there.  Quality is largely determined by the past history of the stand, and you cannot do a whole lot about it at that point.  If the logs are clear and can reach veneer grade, go for it.  If the logs are not clear, then choose to harvest when they reach the best sawlog size for the market.  However, remember the money in the bank, too.  Time is money,  so if the time it takes to get the extra size is offset by the time value of money to get there, then you might think about re-establishing a new stand with the best species and go into the fast growth phase of the cycle.

This perspective is largely financial.  Landowners have other objectives as well.  In the end, the objectives of the landowner establishes the boundaries and creates the basis for making the decision.
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

stonebroke

What happens if you are in a windy place?

Stonebroke

tonich

Very well said, WDH!
I almost forgot the economical end of the question.  :D ;D :)

Ron Scott

WDH explained the professional judgement to be considered as to when to use shelterwood as the management direction.

In a "windy place", leave a buffer of trees as a windbreak around the stand perimeter and especially against the prevailing winds to prevent windthrow of the shelterwood trees. This will also help prevent the stand from drying out excessively.

Also, in an excessively windy area and with shallow rooted species, a shelterwood might not be the best management prescription to use.
~Ron

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