VWA May Members Meeting and Field Trip to Glen Arm Trees
On a cool and sunny May morning, 15 VWA members set off to visit Glen Arm Trees to learn more about agroforestry and what it takes to grow trees and then turn them into furniture-grade timber. Glen Arm Trees is situated an hour’s drive north of Melbourne’s CBD on an agricultural property in Romsey, Victoria and they grow Australian hardwood to make premium timber for furniture makers and bespoke building projects.
We were greeted by Tim and Tim (the two Tims) and after a quick check to make sure no-one got lost on the way, we set off to visit their youngest “crop” of trees. As we headed towards this first location on the property, we discussed the long-term timeline that timber growing takes. Whilst most agricultural crops take 3-6 months to grow and harvest, trees can take a minimum 25 years from seedling to timber depending on the species.
In this first plantation, they had 16-year-old shining gum trees, set 4 metres apart in neat rows. As we stepped foot into the trees, Tim R explained that to give their seedlings the best chance to grow into fully fledged trees, they had to clear the land of any competing species, but the main competitor was grass. This improves the survival rate of seedlings from 3% up to 97%. They cleared the grass using a recognized chemical treatment, then ripped to create grooves for water penetration into the soil and define the rows. Then a planting group of friends and family were corralled to put the seedlings in the ground. From there, the trees were protected from cattle and wildlife as best as possible using a variety of physical barriers.
Tim then explained that there were 3 qualities that make a tree “furniture-grade”:
• Straight growing
• An absence of lower limbs
• A wide trunk
Making trees grow straight.
The crown (top part) of a tree will grow in the direction of light to maximize the amount of photosynthesis. By planting trees close together, competition for light is fostered promoting straight upward trees growth in the early years. Any trees that grow bent, twisted or double trunked will eventually be culled.
Pruning tree limbs.
Once the trees reach approximately 10cm in diameter, the lower limbs of the tree are pruned to confine knots and other defects to the central core of the tree. This leaves clearwood around the central core which can be milled for high quality timber.
This pruning happens yearly, until the tree has a straight and pruned stem up to the expected sawlog length. Glen Arm Trees has pruned trees to 8 metres, allowing milled lengths of over 6 metres.
A wide trunk.
Each year, trees grow an extra layer of timber on their outer side, which are often referred to as “growth rings”. The thickness of the layer is influenced by the sunlight, water and genetics.
One way that agroforesters can promote trees with wide trunks is by “thinning” their crops, which involves cutting down neighbouring trees in the plantation to allow the target tree to access more sunlight. The added sunlight and reduced competition for water and nutrients will then hopefully promote wider growth rings leading to a wider sawlog which in turn gives greater timber yield. Interestingly, this means that the trees on the outermost edge of the plantations at Glen Arm Trees were consistently the largest we saw, as evidenced by this 90cm wide shining gum which we gathered round for a group photo. If you look closely at the trees behind you can see they are all slightly thinner.
The other factor that agroforesters can control is timber species selection, as different species will grow at different speeds and have different target end timber products based on colour, hardness and durability. The other factors to consider are environmental including selecting species based on expected rainfall for the growing site.
Based on the above, Glen Arm Trees primarily grows:
• Shining gum (eucalyptus nitens) – a pale timber suitable for internal joinery, and furniture
• Spotted gum (corymbia maculata) – light to dark brown with wavy grain, commonly used externally for a range of building applications
• Sydney Blue gum (eucalyptus saligna) – a dark pink to reddish brown timber, very hard and suitable for external and internal uses such as cladding, decking, joinery and furniture
After wandering through the plantations we stopped for lunch and thought deeply about how we’d just soaked in 26 years of growth in a whirlwind 2 hours! As we lunched, the two Tims and Steve (another agroforester) explained the next steps of turning trees into timber which were felling, milling and then drying.
We headed back out to the oldest plantation where a 26 year old tree had been felled the day before. The two Tims and Steve demonstrating loading the sawlog onto their portable bandsaw mill which allows them to take cuts along the length of the tree to make large slabs of timber, aka milling slabs.
This is where all of the work planting, pruning and thinning is put to the test as the tree is cut into, the lack of defects in the clearwood reveals itself. This is seen in the photo below, where Tim is showing how the knots have been kept to the centre of the board and the timber on either side is clear of any defects.
The bark is removed from the slabs and taken to the solar kiln, where it is dried to remove the moisture form the timber. The solar kiln uses the sun in two ways:
• to provide heat to dry out the timber
• to power solar panels which switch on fans to circulate air through the kiln to accelerate the drying process.
The timber could be stickered and dried out in the open (known as air-drying) but that can take up to 2 years. Using the solar kiln reduces the drying time down to about 3 months over a summer.
The drying process is really where the tree becomes useful timber as it is dry enough to be worked and to remain stable. However, drying the timber too quickly can cause it to crack, warp or case-harden which can make it unsuitable for certain applications such as furniture making.
Once dried – the timber can then be recut on the mill into specific dimensions and then loaded up into the racks, ready to be sold. This last step means that customers can walk away with timber that can be ready to use for their projects.
And with that, with our lungs full of fresh air, and minds full of new hands-on information we had to sadly call it a day and head home. It was inspiring to see how timber can be produced in commercial quantities in a considerate and intelligent way – a far cry from the indiscriminate clear-felling practices that have consumed much of the native forest across Australia.
If you are at all interested., the VWA will be aiming to make another trip out to Glen Arm Trees to visit again – so keep an eye out on the newsletter for more details.
You can also find out more about agroforestry at https://agroforestry.net.au and in Rowan Reid’s wonderful book – “Heartwood: The art and science of growing trees for conservation and profit by Rowan Reid (2017)”.
If you’d like to see some video action of the day, we have some posted here on our social media.