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Mechanised or horse logging

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These notes were made quite recently by a doctor from The University of Aberdeen and Simon Lenihan, of Celtic Horse Logging.The doctor has long been concerned about the effects of machine logging in Scotland and it's impact on The Forests, Rivers, and Loch's. After seeing Simon's team at work in Scotland, they made a sample study of a nearby plantation block. The logging team would consist of 3 men, two horses, whilst the machine team would probably be along the lines of a small thinning harvester, forwarder 3-4 tonne capacity.

 

Comparison of mechanised logging with horse logging

Example a 100-acre Scots pine plantation, 45 years old and unthinned, average tree size = 0.25 cubic metres, stocking density 800 trees/acre, so 200 cubic metres/acre, and value of one acre is £6,000.This is based on 1 cubic metre with a roadside value of £30 felled and extracted to roadside ready for collection.

A useful method to find the average size of trees in a plot is as follows. The size in cubic metres per tree and the use of such timber are

0.1 deadwood, chipwood and fencing material

0.2 chipwood and fencing material

0.3 chipwood and small saw logs (final crop)

0.4 chipwood and large saw logs (final crop)

The average tree in this case is 0.25, equivalent to 4 trees per cubic metre and 200 tonnes per acre at a stocking density of 800 trees/acre.

Now imagine that you cut all of the 800 trees. You then allocate them to the specifications required by sawmills. All twisted and dead trees go for chipwood and amount to 33%, all small straight timber is used for fencing material and amounting to 33%, and all saw logs amount to 33%. Note that when you remove 25% of all the small-diameter trees, you do not remove all the crooked ones, because some trees have the bottom section of the tree straight though the tops are twisted. Using the above three categories at 33% each, the poorest 33% of the standing timber has a value of £20/cubic metre at the roadside ready for collection. The middle 33% of the standing timber has a value of £30/cubic metre at the roadside, and the top 33% of the standing timber a value of £40/cubic metre at the roadside.

Thinning by motor manual felling and horse extraction, on a sample plot of one acre, would involve a complete selection thinning, removing the poorest trees. These would be all trees of 0.1 cubic metre, resulting in a volume to be thinned of 25% or 200 trees. A 25% thinning that removed all trees of 0.1 cubic metres each would produce chipwood and fencing material at about 50:50 each. For 10 cubic metres of chipwood the timber sale yields £200 and for 10 cubic metres of fencing material the sale is £300, so the total income from timber sales on one acre is £500.

The value of the timber stand on one acre prior to thinning is £6,000. Thinning removes 200 trees at 0.1, which increases the average dbh (diameter at breast height) from 0.25 of a cubic metre to 0.30. Because the value per cubic metre is now £35, the value of this one-acre stand has risen to £6,300. The cost of harvesting 200 trees at 0.1 or 20 cubic metres, using horses, involves two days' work at £500/day, totalling £1,000. The income to the landowner from timber sales is £500, so the short-term loss to the owner is £500, but the stand has increased in value by £300.

Also, with a growth rate of 10 cm dbh over 5 years, this would increase the average tree size by 0.2, bringing it up to 0.5 cubic metres. Moreover, the value of the one-acre stand has now risen to £9,000. This is an increase of £3,000/acre, and in a 100-acre stand the corresponding increase would be £300,000. This would be the final thin, and would leave a valuable crop that has been selectively thinned and that will be more likely to withstand the elements. Horse extraction causes no damage to soils, watercourses and the remaining standing trees. It is the only sustainable method of tree harvesting, and this sustainable method is powered mainly by hay and grain produced by our solar system.

Mechanised logging takes 25% of the timber in the first “thinning”, which in fact is not thinning but clear-felling along a double linear row. The machine will have to take a double row for access into the above example of a very densely planted wood (this would not apply on a less densely planted wood). Whether the machine takes a single or double row, it will end up taking the average tree of 0.25 cubic metres throughout the stand Over two days the machine removes 200 trees at 0.25, which equates to 50 cubic metres at £30/cubic metre. The income to the contractor is £1,000, and to the owner £500. The value of the one-acre stand prior to machine thinning is £6,000, the value afterwards being £4,500. This equates to a gross loss to the owner of £1,500, and a net loss of £1,000 if one allows for the income of £500.

For the sake of argument, let us assume that the machine causes no damage to ground and to the remaining standing trees (an assumption clearly at variance with the facts, as anyone can see on the ground), and hence that there are no side-effect costs. Given a tree growth rate of 10 cm dbh over 5 years as above, this would bring the timber stand up to 0.45 cubic metre/tree. It would take over 30 months of growth for the sample one-acre plot to be worth £6,000 again.

If the machine takes out 4 racks, this would equate to almost 25%. That would leave many of the smaller-diameter trees remaining, when in sound traditional silviculture they ought to be removed so as to aid better growth from the finer specimen Scots pines that are left uncut.

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These notes were made quite recently by a doctor from The University of Aberdeen and Simon Lenihan, of Celtic Horse Logging.

 

Too much to go into now but who in their right mind would wait till trees were 0.25m3 before thinning?

 

Not wishing to lose 25% of the potential final crop was why I put my racks in perpendicular to the planting lines, with the Holder I could generally get a rack of about 1 in 6 through the crop and take a light thinning in between.

 

The plantations we were thinning were planted 5' by 5' but, by the time we were thinning them, planting practice was 6' in the rows, 8' apart.

 

Two things prevented this being a viable ploy. The first was everyone else bought forwarders and the FC allowed 2 rows out of 8 thinning, second RSPB bought the plantations and cleared them to heathland.

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Too much to go into now but who in their right mind would wait till trees were 0.25m3 before thinning?

 

Not wishing to lose 25% of the potential final crop was why I put my racks in perpendicular to the planting lines, with the Holder I could generally get a rack of about 1 in 6 through the crop and take a light thinning in between.

 

The plantations we were thinning were planted 5' by 5' but, by the time we were thinning them, planting practice was 6' in the rows, 8' apart.

 

Two things prevented this being a viable ploy. The first was everyone else bought forwarders and the FC allowed 2 rows out of 8 thinning, second RSPB bought the plantations and cleared them to heathland.

 

Not sure why plantation had'nt been thinned before, but it was taken as a sample of the area they were in.

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would extraction via winch to ride and then stack with tractor make it any easier ? . only asking as im interested in your thoughts and findings .

 

I was thinking similar but using small excavator with felling shear to drag trees to ride then process with stroke processor on ride enabling brash to be harvested at the same time.

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Not sure why plantation had'nt been thinned before, but it was taken as a sample of the area they were in.

 

Well a point to consider is how much benefit from this late thinning inside the remaining rotation?

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I was thinking similar but using small excavator with felling shear to drag trees to ride then process with stroke processor on ride enabling brash to be harvested at the same time.

 

Thinning is normally delayed because of the costs of doing it, typically with softwoods you need to be in there somewhen around P+18-P+25. The concept is that a marginal thinning will not affect the overall yield and the subsequent increment is fattening better stems. The price:size curve often dictates that thinning at the ideal time will not break even and the total yeild from a thinning may not justify mobilisation costs for the harvesting operation, especially with low value produce like chipwood. To me the stumpage value of woodchip is still zero and the loss of minerals makes it worse.

 

When I was doing it there was no alternative to motor-manual felling and conversion and driving a tractor to a site was not a big expense. So we would even harvest down to a single lorry load. Also there was a blip in the price:size curve for PSR that made this element more worthwhile.

 

With modern harvesters costing so much and their operators less willing to undertake a proper selected thinning I am seeing a general decline in softwood stands.

 

In general the higher final crop returns (in better yield of sawlogs) will not carry the additional thinning costs incurred 40 years earlier.

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Here's an option on the horse, which on the site shown would've been better due to the size of the ridges being worked in.

http://www.youtube.com/watch?v=Qgj_j3AA3gw&sns=em

 

I've used the same type of machine clearing blow on a stepped & sloping site. We were able to cut n clear an extraction route where we wanted. Pushing plates back in and blading stacking / turning areas in the middle of the blow then allowed for a tractor to come in and forward the timber out.

 

In thinnings we can usually get away with a single line for a rack and extract in whole tree or pole length. Yet to try it on selective thin, as pole lengths usually end up with too much marking of remaining trees to be acceptable.

 

There's always a way, it's just if the maths works :)

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There's always a way, it's just if the maths works :)

 

I like that :001_smile:

 

The problem I have with scientific/accademic findings like this, is that no two sites are ever going to be exactly the same, and figures can be made to say whatever you want them to.

 

My approach to softwood thinnings is usually Logs and chip/firewood and where possible forwarding straight from stump, fast in and fast out with minimal handling. Worst case is skid, convert and then forward.

 

Chip is at the highest it's been round us and pretty much makes it not worth bothering with bars or pallet and especially not fencing blanks as they are too fiddly to bother with.

 

Our current machines are all under 5ft 6 wide and tread lightly - we were recently leading timber off of a scheduled monument and made less impact in 3 days of forwarding than another contractor did in a couple of passes with conventional tractor and a teleporter.

 

On first thinnings, generally timber's going to be small enough to hand stack everything without too much bother so minimal rack cutting needed, by the time second thin comes round we can usually ride right through the stand.

 

I do think the low impact motor manual methods have been making a bit of a comeback and there is a wide range of kit out there to do the work but before long I don't think there is going to be the men on the ground to do the work well.

 

Plenty of colleges churning out supposedly ready made "tree surgeons" with enough tickets to fill a pack of andrex, but clueless when it comes to cutting efficiently in the woods, but then how many of them really want to chew their nads off in the woods?

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