Permaculture Principle No 3 - Obtain a Yield

I've just spent a day at our McKerrals Tree Farm trying to work out how to 'take a yield' from something I have to do to manage part of our forestry interests.

Until 2010 we leased part of the farm to another party who grew Eucalyptus Globulous (Tasmanian Blue Gum) to produce wood chips for export to Japan - where it is used to produce high quality paper.  During the summer of 2009/10 they harvested their crop and left me with stumps - from which it is possible to produce what is known as a 'coppice rotation'.

Over the 4 years since harvest each stump has sent up between 2 and 6 separate stems.  They are now from 3 to 8 metres tall.  The task now is to select one stem to grow on - and remove the rest.

This photo shows Soeren (a WWOOFer) starting into the process - using a fantastic little arborist chainsaw I got last week.  It's only 3 kg - and designed to be used with one hand or two.

Soeren is taking out the first stem here.  The next photo shows him about to take out the last waste stem leaving just one (hopefully the best and straightest) to grow on for another 8 or 9 years.


While the little chainsaw seemed to do a great job, I'm very interested to see what a group of contractors we have coming in a week or two use for the task.  Their quote is $638 per 1,000 treated stumps.

Many stumps are easier that the one shown in the photos - but others are worse.  Nearly all have small, dead twiggy bits that need to be brushed away before you can get at the base where the cuts need to be made.  And the tolerance for any damage to the retained stem is ... zero.

Having done a few trees now myself, 63.8 cents a tree seems like not a lot of money for the job.

In David Holmgren's book Permaculture - Principles and Pathways Beyond Sustainability the 3rd principe is Obtain a Yield.  In this spirit I looked at the coppicing process and wondered whether it might not be possible to 'obtain a yield' beyond the 2022 chip harvest.

In the normal course of plantation forestry the pruned stems are just 'cut to waste' - that is they are just allowed to slowly rot on the ground.  It occurred to me that perhaps the pruned stems might be used as firewood?  From the research I've done, Tassie Blue Gum is regarded as reasonably good firewood - and, if we're using something that would otherwise just decompose, it is definitely from an 'eco-friendly' source.

The issue is that, when cut, it is green and not suitable for burning.  It needs several months (at least) to cure.  So we need a way of allowing it to cure - before being able to cut and package it.

Step 1 is to trim the pruned stems to the point where the diameter gets too small to make acceptable firewood.

Step 2 - we drag it to the edge of the plantation.

Step 3 involves using a hand held machete to trim off the leafy branches and twiggy bits.

What we then have is a trimmed sapling up to 100 mm in diameter at one end and down to about 40 mm in diameter at the other end.  They are between 3 and 5 metres long.  They are ready for 'curing'.

I've had various ideas about what to do next, but the best so far involves building a simple frame from shorter bits that keeps the wood for curing well off the ground.  The next photo shows the first attempt.

I emphasise ... this was the first attempt.  The second was lower to the ground (half this height) and used heavier stems.

The stems are dug in about 3-400 mm - and I use the small chainsaw to 'shape' the top of the post into a U.  With this one I put a screw in to hold the cross piece.  With the heavier stems on the Mark II version - my screws were not long enough - so they just rest in the U.

Once I have sufficient stems to make a bundle which I think might weigh between 500 and 800 kgs, I used a polyester strapping system to hold it all together.  

The plan is to come back when the stems have cured and tighten the strapping up.  Then, with a tractor with a front end loader, I can lift the firewood bundle onto a truck or trailer and bring the firewood back to Moora Farm.

There I have another tractor with an FEL.  I will use it to put the bundle of cured firewood onto something I build late last year from scrap I had from dismantling cattle yards when we first came to Moora Farm.

I built it to help me cut up 'logs' of sawmill offcuts I get from Frosts Sawmill in Monegeetta.  These 'logs' are about 5 m long, 1 m in diameter and bound with steel strapping.  They are a great way to get firewood, but lying on the ground, it's hard to finish cutting it to length.

With this table, I just lift the 'log' onto the table - and cut it there at a comfortable height and with no risk of blunting my chainsaw chain by touching the ground.  I think it will work just as well with my eco-firewood bundles.

So - I'm taking firewood orders.  Maybe for this winter - we'll have to see.

Oh - and, once the coppice pruning is done and the firewood recovered, the plantation looks like this.

Thanks Soeren and Alessio (my helpers)!  Although we only did about 120 stumps we learned a bit about what might or might not work.  There are another 46,880 stumps to do over the next few months.