iDRY Vacuum Kilns

Sponsors:

Seasonal Weight Change

Started by Don P, February 08, 2003, 07:14:11 PM

Previous topic - Next topic

0 Members and 1 Guest are viewing this topic.

Don P

No, not the post-Christmas bulge ::) ;D
I was wondering, is there a noticeable difference in the weight of a load of logs in winter vs spring or summer?

Minnesota_boy

I don't think there is much change.  they might be slightly heavier in the summer, but not enough to notice.  They always feel heavey to me.
http://www.boomspeed.com/rmorrison/forklift.jpg
I eat a high-fiber diet.  Lots of sawdust!

Jeff

Our loads of aspen chips are much heavier in the winter and the lumber is much heavier according to the handlers. I think that sap going out of the trees in the winter and coming up in the summer is a falicy.

I have always thought that the summer foliage drinking all that moisture is why the wood is lighter in the summer months. Any Forester facts out there?
Just call me the midget doctor.
Forestry Forum Founder and Chief Cook and Bottle Washer.

Commercial circle sawmill sawyer in a past life for 25yrs.
Ezekiel 22:30

Norm

When we had the extension forester out to give some advice he said not to use Tourdon to treat the stumps the first of Feb-to May. When I asked why he said something about the water moving up from the roots and it didn't work as well.

We cut down a couple of big cottonwoods recently and could hardly get the chainsaw to cut because of all the water pouring out. It didn't seem that bad when I've cut them in the summer when their all leafed out.

chet

The problem that was referred to with stump treating with Tordon (as well as many other stump treatments) in spring , is that the flowing sap will delute or even wash the chemical from the surface of the stump. By using a different carrier (a  bark penatrent) and treating the sides of the stump rather than the top, you can normally solve this problem.
I am a true TREE HUGGER, if I didnt I would fall out!  chet the RETIRED arborist

Minnesota_boy

Loggers here say there is a lot of variation in the weight of a single species (aspen) but I've not heard of seasonal variation.  They say they can have two identical loads and one will weigh light and the next will cost them a fine for overweight.
I eat a high-fiber diet.  Lots of sawdust!

Jeff

I'll send this thread to the procurement forester at G.P. here in Michigan. Hope he has time to answer, he is leaving for China tuesday. Forester Frank is a member of this forum and a good guy. He's just TOO BLAME BUSY :)

He should know, If I don't get a answer there, I have sent a note to member Sylvus who is an MSU extention forester, and if that don't work I'll call the wood procurement guy at the local  Wereheuser (sp?) plant and find out from him. They would have to know.

I want to know!!
Just call me the midget doctor.
Forestry Forum Founder and Chief Cook and Bottle Washer.

Commercial circle sawmill sawyer in a past life for 25yrs.
Ezekiel 22:30

Corley5

It depends.  If I'm cutting timber in the winter I'm lighter.  If I'm not I'm heavier ;D
Burnt Gunpowder is the Smell Of Freedom

Forester Frank

Normally I put on weight from Thanksgiving until January, but it is not from eating aspen. It's from eating turkey, candy, pumpkin pie, Christmas cookies, and all that other good stuff you eat during the holidays! :D
Forester Frank

Forester Frank

Okay here is a more serious answer. I will start with a few things for y'all to think about.

Think of the standing tree as a sponge. Like a sponge, the tree will soak up water when it has empty cavities to fill. When you wring out a sponge, it still has the ability to take up water. When it is bone dry, the sponge is hard (strong), and has the ability to take up more water.

Now think about how dry it is in the winter. From a humidity stand point alone, the relative humidity is lower, thus the tree will be trying to take up more water in winter to balance itself, or reach an equilibrium state of moisture content.

Are you still with me?

More things to think about - Jeff is on the right track with foliage making a difference in the hydration of the tree. Also consider external factors such as relative humidity, rain, heat/temperature in the summer.

The undersides of leaves have little openings, called stomata, that open and close to allow leaves to take in, or release moisture. Roots systems, as you know, also take up moisture. Are they taking up more in the winter, or in the summer? When is the tree most thirsty?

Although it is cold in the winter, and the tree is dormant, isn't it also very dry in the winter?

Think about this some and I'll add some more comments in the next day, or two before I head to China.
Forester Frank

Ron Wenrich

Never under estimate the power of stupid people in large groups.

beenthere

Forester Frank

""Now think about how dry it is in the winter. From a humidity stand point alone, the relative humidity is lower, thus the tree.........""

My understanding is that the RH (Relative humidity) is normally higher in winter than in summer, if you are outside a heated room. Usually wood stored outside will increase in moisture content in the winter but decrease moisture content in the summer. There is more moisture in the air in the summer than in the winter, but warmer air has more capacity to hold moisture than cooler air. Thus the term "relative".

True, if inside a house that is heated in the winter, the relative humidity is lower due to the heat and due to the "dry" air. I haven't yet sorted out if this still supports your explanation.
south central Wisconsin
It may be that my sole purpose in life is simply to serve as a warning to others

Ron Wenrich

My problem with the relative humidity argurement is that you are dealing with a closed system.  The bark protects the interior of the tree, and most moisture loss is longitudinal and not radial.

The draw of moisture from the roots is governed by the need from the bud end.  Buds break dormancy due to photoperiod (length of day), and ground temperature.

Until there are leaves, the moisture is pumped up, but doesn't have any place to go.  When the leaves emerge (or needles get out of the dormant period), then your system is opened up.
Never under estimate the power of stupid people in large groups.

Don P

For reading on the subject, this is an article that explained things where I could grasp them. The section starting at water loss interested me most. A point was that since water moves by capillary action a tree cannot afford to lose its water column.

http://www.dsisd.k12.mi.us/mff/Environment/WinterTrees.htm

What I was hoping for is a kind of rubber hitting the road type of confirmation, namely does weight scale get changed by season, or does an average truckload weigh more at one time of year or another. I liked Jeff's observation about the trailers weighing more, real number observation. It just seemed that people buying or selling by weight would be able to tell about water flow pretty accurately.


OneWithWood

I won't get into the RH discussion.  I pruned about 100 six year old black walnut trees yesterday and I can safely say there was plenty of H2O in those trees.  I have never seen sap run like that in the summer - but then again I rarely prune in the summer.
As far as weight goes - I have not noticed any appreciable difference while cutting firewood.  The stuff is just as heavy any time of the year :-/
One With Wood
LT40HDG25, Woodmizer DH4000 Kiln

Jeff

Well, I don't think these figures will help us find a definitive answer but maybe create more questions. Seems that species makes a difference. Here are some real numbers for you Don. ;D
---------------------------------------------
Jeff;

There are many factors that impact seasonal differences in wood weight, some more important than season.  It's not a straight-forward situation.  Nevertheless, the following illustrates how weights can vary with factors such as stick size, season, species, moisture content, etc.  The following numbers came from records of 2000+ loads at the MeadWestvaco mill in Escanaba.  

-Bill
10 February, 2003


All are pounds per cord, winter and summer (respectively)

Dense Hardwoods         5480     5650   (e.g. sugar maple)
Medium Dense Hdwds   5140     5140  (r.maple, w.birch, balm, aspen)
Aspen                             4980     4960
Pine                                5100     4751   (much was from concentration yards, though)
Hemlock                         5220     5116
Balsam                           5040     4718

Range in Wood Weights (pounds per cord)

Mixed Dense Hdwd   4660-6300
Red Maple                 4180-5940
W.Birch                     4300-6400
Balm                          4420-6540
Aspen                        4260-6280
Pine                           4360-5960
Hemlock                    4560-6380
Balsam                      3940-5760
Spruce                       3960-5940

Affect of Stick-size on Pounds per Cord (4-8" - 9-12" - 13+", respectively)

Mixed Dense Hdwd  5220   5460   5540
Med. Dense Hdwd    5140   5100    ---
Aspen-R.maple        4960   5040    ---
Pine                          5060   5100    ---
Hemlock                   5160   5200   5320
Balsam                     5040   5040    ---
Spruce                      4480   4660    ---

Just call me the midget doctor.
Forestry Forum Founder and Chief Cook and Bottle Washer.

Commercial circle sawmill sawyer in a past life for 25yrs.
Ezekiel 22:30

swampwhiteoak

I pondered this last night after I read this thread, nothing to add really.  I guess what I get out of this is it doesn't really matter winter or summer given the same species.  The differences look too small to be significant.

Don P

Bingo, Thats the kind of stuff I wanted to see, Thanks :)
As I read it, its saying the range of averages is greater than any seasonal differences in moisture level...like you guys and the books were saying, moisture content doesn't seem to vary very much seasonally. You oughta see all the people that would shock :D.

Minnesota_boy

A quick lookie-see says that, on average, dense hardwoods are a bit heavier in summer than winter, while the reverse is true with softwoods.  Is that because the softwoods lose moisture more quickly than hardwoods?
I eat a high-fiber diet.  Lots of sawdust!

SwampDonkey

The pulp mill at Nackawick always had seasonal adjustments for weight (thus price) and it was written into the negotiated contract.  In our winters frozen wood doesn't dry, come April and warmer temperatures that changes. If there are extended warm periods in the winter then respiration can use water in living tissue. Another note, balsam fir is heavier than spruce when green, but not when dry. The more fir content in the load, the less price per unit (cord/tonne) at local mills.
"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)))

Don P

 All summer I couldn't get above 165. I hit the scales at 180 the other day. Must be the humidity  ;D

Thank You Sponsors!