Total green weight of trees

#1
I´m working on a quote where part of the operations is to move trees from a small island to a barge with helicopter. Weight is a big issue when calculating how many turns the chopper must do to clear all the trees. Regarding the chopper costs NOK 13000 an hour I realize that the potential for loss is great so I need to do this right. I have found a lot of green log weight charts but no info about total weight of trees (canopy and all) Do you guys know or have any facts or rules of thumbs of how much the canopy makes up of the total weight of the tree. Most of the trees are sitka spruce.
You can see a bunch of pics of the trees and the island here. web page
 

cerviarborist

Well-Known Member
#3
I've never encountered a question like that. I'm thinking though, that you could reach a rough approximation on an excurrent tree like a spruce, by using the height of the tree, and the radius at the base, to calculate volume as though it were a cylinder. (Height x pi) x (radius squared) The stem of the tree of course is not cylindrical in shape, but in a rough approximation the excess volume that you'd get as a result of calculating it as a cylinder, rather than as a cone, would be offset by the weight of the branches.

Once you had the volume calculation, you could then convert it to cubic feet and use a green log weight chart.

Perhaps you could try testing the calculation on Sitka specimens small enough to weigh, to see how it works out. Small spruce seem proportional to larger specimens.

I also found a page with algorithms for calculating tree weight. You can view them here.

http://www.shodor.org/succeedhi/succeedhi/weightree/math1.html

The algorithms are taken from "Tables for Estimating Total Tree and Product Weight and Volume of Major Southern Tree Species and Species Groups" Joseph Saucier and Alexander Clark III , Southwide Energy Committee, American Pulpwood Association Inc., Nov. 1985.
 
#4
Having lugged my share of logs, and dragged my share of brush, I've gotta say once you have the log weight of the tree you're just about there. Are needles and stems really adding all that much? Especially with an excurrent form.

Tim
 
#5
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Having lugged my share of logs, and dragged my share of brush, I've gotta say once you have the log weight of the tree you're just about there. Are needles and stems really adding all that much? Especially with an excurrent form.

Tim

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Yeah man! Especially if there are cones. They weigh alot and would be really hard to calculate!
 
#6
i have a great book showing green weights on most common species. gives you weights on 1 foot lengths from 10 to i think 24 inch diameters.

in my locker at work ill make a point to bring it home this week.
 

Gord

Active Member
#8
Re: Total green weight of treeslonglining them out

Are you longlining them out after they're felled? You could cut one smallish one down, then weigh it in manageable pieces prior to the helicopter arriving, but it would likely be a waste of time. I think your best bet though would be to go small for the first few picks and see what the pilot has to say, then you'll be able to eyeball what a good max weight looks like after getting a feel for it. The total weight of the trees will vary a lot even for the same species/height/DBH as some will be limbier/bushier than others. The heli cycle time will be quick, I'd worry more about having enough slings on hand so that there's no waiting around rather than getting max weight every time. What kind of helicopter is it?
 
#9
Re: Total green weight of treeslonglining them out

Thanks for input. I see that my post may be a bit confusive. I´m working on a qoute and I need to calculate the costs. When or if we get the job we will work it out with the pilot and with my knowledge of the guy this will work great. The chopper can carry max 1,2 metric tons but the average will be more like 0,8 to 1 metric tons. So you see that if I miscalculate the total mass to be moved economy will be really bad.
I have done a pretty accurate estimate of how much lumber there is, I have calculated the green weight of the lumber but since we are going to fly the trees out with the limbs on the limbs are the big X.
If I overcalculate I might loose the qoute, if I undercalculate I will loose my profit and maybe more.
So, my question is: do you have any rule of thumb for calculating the ratio of stem and brush in a tree (sitka spruce)?
 

southsoundtree

Well-Known Member
#11
Seems like time of year will factor in a lot. Cones, sap. Also, health of the stand--stress cone crop.

If felling them, you will be loosing some of the cones and needles, and a few of the limbs.

If they are closed canopy growth, you will have much less total weight compared to the green log chart. Seems like volume of a cylinder multiplied by weight per cubic foot of green wood may get you closer than a green log chart, but its armchair estimation.

Little experience here with spruce. I think that the wood is relatively light, so foliage/ cones will make up a larger amount of total weight. I know that for another species, noble fir, abies nobilis, has heavy limbs that always surprise me at to their density.

Will they sit for any length of time on the ground in the sun to dessicate?

foliage/ limbs/ cones/ tops could double the weight of the tree compared to the logs (from my armchair).

I'd rather lose a bid than lose my bidness with such a hard estimation. Bid high.
 
#12
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Will they sit for any length of time on the ground in the sun to dessicate?


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We're talking Norway here, autum and west coast. Not much sun, but lots of rain
 

southsoundtree

Well-Known Member
#14
That seems like really hard job to quantify if you have a large number of trees. Stressful for a bidder. Hope it works out close to estimations and profitably for you.

Why is this being done?
 

jmcscrap

Active Member
#15
Have you contacted any of the logging outfits that use choppers to get wood out and how they calculate what they pull. I realize they are mainly pulling the stick out, but it's a thought?
 
#16
Quite hard, but i went for the worst case scenario I possibly could make within reason. I we win we´ll win big. Did you see the trees in the albumlink in the first post?
The island is a habitat and roosting area for seabirds, they are now pushed away by the fast growing spruces. The Norwegian environment authorities have decided to remove all the coniferous trees on the island in an attempt to raise the population of birds. A neighbouring island was cleared this winter, but here all the vegetation was chipped on situ, a much cheaper procedure. The purpose of removing all biomass now is to get a chance to study the impact on wildlife from two different procedures.
Our competitors will most likely use harvesters and large chippers and transport them out on the island with barges, transport all the biomass away with the barges and try to remove all tracks with excawaters. Its gonna be interesting to see how our method compares with the competitition. The evaluation of the quotes are weighted with 35-40% price and the rest 60-65% method and qualifications. We believe that our method which leaves the ground on the island untouched is a better way in this case. I´ll try to remember to keep you posted with the outcome.
 

AspenArbo

Active Member
#18
I was in on some of the research that Dr. Ball did at South Dakota State. Leave weight (on elms anyway) is less that 1% of the overall weight of the tree. I would imagine that needles are a bit heavier, but not significantly. Therefore, I would say go by the green weight charts. Also, the weight of the wood drops significantly after a few days laying on the ground cut up.

Another question to maybe ask is 'is the chopper effected by the wind drag the needles will create or is it strictly by weight?'

Good luck!
 

mdvaden

Well-Known Member
#19
Geez ... spruce foliage is heavy.

We removed several from our home and I recall the weight. Depends on species.

You ought to cut some limbs somewwhere and strip the twigs and foliage off a branch and weight that. The foliage alone won't give you the weight you want to know.

And weigh the stripped limb.

The wood you would know. So it looks like limb weight is what you are after, because odds are you are not taking entire trees at once? Are you?

If the foliage is wet, that may make a small difference too. You would do this on a dry day I suppose.

All spruce are different. You would do best to get limbs from those same spruce and weigh the foliage and twigs, and limbs from them.
 
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