Technical Question: wind vs. woodlot operations

[John Vander]

With 25-35m/s winds, if a woodlot is opened up for operations, which would be the best way to avoid windthrow? Is it better to open up against the wind (making the entrance to the lot not facing the domenant wind direction) or to open up and fell a wind path in the same direction as the wind?

[beenthere]

Strong wind... 55 - 75 mph  (or I converted wrong). 

Interesting question. Think I'd want to work on the down wind side and cut trees so as to reduce the effects of wind moving through the lot.

[jamesamd]

I got 78 mph,thats hurricain speed.I hope they are palm trees. 

Jim

[John Vander]

Thanx for the replies gents. We get some scary winds here. Now in spring we had a couple of severe ones come through, but typhoon season takes a toll on stands here. I noticed some guys opening a stand,  removing the buffer trees with the valuable trees all exposed. With no wind brake on the outside I suspect someone is going to be cleaning up storm dammage soon.

[Clark]

I often see where a stand was opened up and when the outside trees are left more intact, the stand fares better. If you hammer the outside trees then those that haven't been exposed to the full brunt of the wind now are and often times they react by leaning or tipping over.

I always try to leave the side(s) of the stand facing the strongest winds nearly untouched. In pine, for example, we thin down to ~90 BA, along that leading edge I'll leave it at 110-120 BA.

Clark

[Gary_C]

Clark is right and that is the most common method of attempting to avoid windthrow. But you do have to accept the risk that goes with any thinning that you be making the stand more succeptable to damage. At least for some limited amount of time.

Sometimes it's just like rolling the dice and hoping that no strong winds will arrive shortly after you thin a stand.

And I would love to see some pictures of the stand. We love pictures.

[SwampDonkey]

There may be something to garner from this paper.

http://www.for.gov.bc.ca/hfd/pubs/docs/wp/wp01.pdf

Used to have to deal with windthrow when we designed and mapped harvest plans.

[John Vander]

SwampDonkey, thanx for that link!

[Ron Scott]

Yes, to what's been said. Manage the stand for wind protection, especially the first thinning.

[mesquite buckeye]

Always a bit of a dice throw, especially the first year or two after a thinning. Thinning a stand also seems to increase glaze damage for the first couple of years at least.

[petefrom bearswamp]

When practicing I never took wind throw into account in our hardwood stands.
Never seemed to be much of a problem.
Always a scattered few individuals that blew down but not very many.
This holds true for my home forest of Northern hardwoods as well as my 2 Oak properties about 70 miles west of my location near Corning NY.
Visited both of these last week and yesterday, only found 3 trees blown down, 1 aspen and 2 oak.

[SwampDonkey]

The PNW and Japan to I suspect have a lot more heavy wind events. Softwoods are generally less wind firm then deep rooted hardwoods. There is even a difference between our balsam fir and spruce here in the NE. A balsam fir is generally well rooted, but the stem is weaker than spruce, they snap off. Spruce uproot. This was real evident in the November 1995 wind storm in the Christmas mountains of NB. Aerial photos showed the spruce uprooted most of the time and the fir just snapped off. The only time I see hardwood flattened on any scale is in tornado bursts. Hurricanes usually loose their punch before they get to NB.

[Ron Scott]

Yes, the softwoods and especially red pine here is more shallow rooted than the northern hardwoods and much more subject to wind throw, especially during the first thinning's. There is a difference in their ecological (soil) land types.

[John Vander]

 Some idiots opened this stand of trees from the side. They made the road straight up the side of the stand, creating a path for destruction. With the last rains we had, already some soil started coming down. Construction workers are now battling against time to fix up the mess before the rainy season that starts in June. Expecting a big landslide here. Located under this stand is a road, and just underneath it is a school. Town government dont do anything about it. No one is being held responsible.



 


 

[John Vander]

 

 
Here is some detail on the situation.

[SwampDonkey]

Another thing we had to do on the coast was survey gully systems. I've seen more than one block that was 'no logging' because of gulleys and old evidence of slope failure. Often on the fans at the bottom was huge Sitka spruce timber to. No touch.