Timber harvesting at Bambra Agroforestry Farm
Sustainable wood from multipurpose farm trees
Selling, Felling, Milling and Drying
I made this table from a mountain ash (E. regnans) we planted back in 1987. Harvested and milled with our bandsaw in 2012. Air dried for 2 years. Lots of Kino due to drought stress but it all looks good on the quartersawn boards. No knots because of pruning. Log was about 60 cm diameter
The tree was growing well but then lent over a little during a spring storm. If I had left it to grow on it would have developed tension wood on the upper side of the lean that would have made it difficult to mill and dry. So I harvested it and recovered almost 2 cubic metres of pruned log and some knotty logs from the upper section. The rest was firewood. Removing the tree gave more space to the other eucalypts and a neighbouring Blackwood. I have since planted some Dropping Sheoak close by.
The floating table top is made up of seven quartersawn boards (nominally 1.5 inches thick) buscuit joined together. Quartersawn timber expands and contracts less with changes in humidity than half that of backsawn boards but the top still moves so it is fixed down with small timber locks that allow movement. The sapwood of mountain ash is not susceptible to Lyctus borer so I was able to use boards with a natural edge on each side to give the appearance of the top being a single slab. Legs made up from the same timber laminated together to give a more bulky look. The kino veins and some larger pockets of kino add to the appeal. The corewood (the inner 10 to 15 cm of the log) was rejected - this contained the low density juvenile wood and all the knots and associated rot. Although just 25 years old the mature timber (formed after the tree was about 8 years old) is as dense as 'old-growth' mountain ash the only difference being that the growth rings are much wider. Mountain Ash is not durable so the table will be kept under cover. The table was finished with 3 coats of timber oil (lightly stained to regain a natural colour) - this can be easily repeated to keep it fresh.
History of Timber Harvesting at Bambra
We first planted trees at Bambra in 1987. We pruned and thinned to improve log quality and promote diameter growth. At the time there was no market for plantation eucalypt timber and certainly no premium for pruning. But, native forest logging was coming under the environmental spotlight. The community were starting to look for alternatives. There was plantation pine but not everyone wanted pine furniture.
Today commentators and interest groups are asking why there is no sustainable, farm-grown native timber available to replace the timber we once got from public native forest. There are eucalypt plantations for pulp but you can't mill them for furniture timbers.
We have some logs. Not enough to supply a mill - not that there are native timber mills left in our area. But, we have enough to test the market, explore the prospects for farm grown timber, and to encourage others to plant and manage trees for the future.
Our first trial harvest of pruned eucalypts involved 10-year-old trees (30-40cm diameter). That only proved that backsawing of Shining Gum created drying problems. Our 16-year-old harvest (50cm) was more promising. It proved that growth stresses were not an issue in well managed straight trees and that quatersawing produced stable boards with lower risk of internal checking and highlighted fiddleback grain if present. But, the logs could have been bigger.
Our latest harvest (above) was of 60-70cm diameter pruned logs. These are destined for veneers. Sixteen cubic metres of logs were felled and shipped to China to be sliced in 0.6mm veneers then sent back to Melbourne. The buyers were looking for a white hardwood from sustainable planted forests and if the trial works they'll pay prices higher than any native forest eucalypt.
I've now got my own bandsaw mill to process the leftovers (top logs ant thinnings). I'll dry the timber slowly then finish in a kiln.
No one knows where the future markets will be for farm grown timber let alone what prices we might get. All you can do is learn about the qualities of the different species and manage for quality logs (fat and clean). What is clear is that you can't sell quality logs in the future if you don't plant and manage them in the past. For many the time it takes to grow a forest is a problem - for those of us with logs it means that we are years ahead of our competition.
Below are some photos of our harvests.
Rowan felling a 22-year-old Shining Gum
To accurately fell without damaging other trees I used my remote control 5 ton tractor winch to pull over the tree (after cutting a scarf and back cut). This overcomes the need for wedges and means that I am well away from the action when the tree hits the ground.
The veneer buyer inspecting the log. The verdict: "we'll take a container load" They had to be over 50cm in diameter (small end), pruned and 5.8m long.
Using the logging winch to pull the logs up to the loading ramp. At 1.5 tons each the front end loader couldn't lift them.
Loading the truck - this photo show the load of 16-year-old Shinning Gum which were milled as part of a CSIRO trial
Few shots of Rowan milling one of the top logs from the 22-year-old harvest on his Lumbermate Bandsaw Mill. The timber was then stickered and stacked under plastic to dry slowly.
Furniture made from 16-year-old farm grown Shinning Gum harvested from a multipurpose mixed-species riparian planting along what was an eroded creek.