What to Consider When Extracting Timber

Ben Law
Friday, 15th August 2014

Extracting timber may sound fairly easy, but Ben Law explains the various considerations to be made and the different techniques available. FREE book offer at end of article.

It seems a long time ago that the winter rains receded, but with the added mild temperatures this winter, it was not good for timber extraction. However a dry summer opens up plenty of opportunity and allows access to areas that were too wet to reach in the winter. If I can't extract when the ground is frozen during the winter, then my choice is late summer after the main bird nesting season and flush of spring flowers has finished. 

There are many methods to extract timber but the key is to access your woodland first. Key areas to consider are:

Soil type – A well drained chalk soil will enable extraction in most conditions, whereas a heavy clay soil will need more consideration as to suitable techniques and finding the limited weather windows for success.

Slope – Many woodlands are on hillsides or in valleys so extraction may involve utilising watercourses at the bottom of valleys or log chutes (a series of interlocking plastic shutes in which logs can be sent to facilitate steep downhill extraction). Log chutes are best used with small diameter timber of short lengths - for example, extracting cord wood for firewood use. In extreme situations skylining may be an option, but the use of aerial cable runways is not an option for many in small woodlands although the environment impact of such techniques can be beneficial.

Sensitivity of site – A species assessment should highlight the sensitivity of extraction needed on a site. For example a monocultural coniferous plantation is less likely to need the sensitive choice in technique of extraction compared to that of an ancient broadleaf woodland with a diverse mixture of ground flora. 

Size of timber to be extracted – The size and weight of timber will effect the type of extraction equipment used. A lot of timber I extract is in long lengths of 12-13 metres in length but of small diameter. Poles of this length are often easier to skid out through one channel in the wood and then picked up at ride side rather than going into the woodland and loading them onto some form of forwarder. Large butts of timber weighing over 2 tons are going to need a heavier forwarder and timber crane to move them, so choosing the right time to extract to minimise damage is more critical. Other options for large butts can be to winch them or to mill them where they are felled with a mobile sawmill. Some mills (such as the Lucas mill) are designed to be carried into the wood in pieces and then constructed around the log to be milled. 

Extraction at Prickly Nut Wood

At Prickly Nut Wood, I have created one hard ride from local stone that runs as the main artery through the woodland. This allows all year round, any weather access and all extraction operations work from this ride. There are some areas where I have used horses. Horses cause minimal damage in the woodland and should be the favoured choice in sensitive woodlands. Prickly Nut Wood is a Site of Special Scientific Interest (S.S.S.I.). The designation of the S.S.S.I. is for the bryophyte community - mosses, lichens and ferns. In order to leave a good amount of growing area for mosses on the coppice stools, my stools are cut higher than would be the usual silvicultural practice. This makes an awkward terrain for extraction and for horses. In these areas I use three main techniques: 

1. I use a long 80m long, 16mm diameter extraction rope and a snatch block pulley attached to an anchoring point (usually another tree). The extraction rope has a spliced looped end onto which I attach a logging chain which is wrapped around the log and grips it tightly. The rope then runs to the snatch block which is anchored at the far side of my hard ride and goes around the pulley and is then attached to the towbar of my Hillux. By driving along the hard ride the timber is pulled to the edge of the ride ready for collection.

2. I use a uniforest winch which attaches to the power take off (P.T.O.) of my tractor. The tractor can be parked at the edge of the wood and the timber winched to it. Logging chains are attached to the winch cable and this way more than one timber log can be exracted on each pull of the winch. A manual method would be to use a ‘Tirfor’ or similar winch anchored to a tree. This is a very slow method of extraction but a reasonable option if you are not extracting too many trees.

3. I use my Alpine tractor and forwarder to go into the wood when it is dry and extract with the hydraulic timber crane. One of the most damaging aspects of using a tractor in a woodland is turning around. A tractor and forwarder need space to turn and it is the sharp turning of the wheels that rips through the ground flora and causes damage. The Alpine tractor I use is reversible. The seat and steering column rotate, so that you can forward into the woodland, load up and then rotate the seat and steering and drive out. This removes the need to do any turning within the woodland.

Above all, consider your extraction methods before felling, as this will have an impact on where you stack timber and the necessary access routes to facilitate extraction. 

I have been extracting some of the windblown larch from the winter storms with the alpine tractor - next month you will see what I have been doing with it.

Further resources

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Melissa Hoffman |
Mon, 04/01/2016 - 17:13
Hi Ben, we own the same tractor, and I had a quick question for you. You drive into the woods one way and reverse the seat, and drive out the other, but how do you handle the loads you're pulling? This tractor can only pull from one end, yes?