Monthly Archives: November 2013

Recent New Zealand blackwood articles

The latest New Zealand Tree Grower November 2013 34(4) journal, published by the NZ Farm Forestry Association, contains some excellent articles and discussion about blackwood.

Two articles by tree farmer Malcolm Mackenzie are worth reading.

This article reports the results of a small sawmilling study looking at factors affecting sawn timber recovery in farm-grown blackwood. The logs used came from a 27-year-old shelterbelt, and were on the small side, so the recoveries were generally not that high. But the best log gave a 66% sawn recovery, including 78% of clear blackwood timber, which sells in New Zealand for $3,000 per cubic metre!

Two log quality factors that Mr Mackenzie did not report on were sweep and taper, which can also affect sawn recovery. It would have also been useful to include sawn clear recovery for the entire study, as it is the clear, knot-free wood that has the premium price.

But as Mr Mackenzie says “my challenge to fellow farm foresters is to become more scientific in their analysis of their trees in their growing stages and in their harvest. It takes time but it is useful information. I would ask that we accept the need to share information particularly as it applies to harvest results.” I couldn’t agree more.

These results hint at the possibilities that will result once New Zealand blackwood farmers begin harvesting their well managed plantations in the near future. When this happens someone needs to organise a sawn recovery study of premium plantation grown blackwood sawlogs. I’m looking forward to reading that report.


In the second article Malcolm Mackenzie talks about his ideas regarding collective marketing of New Zealand blackwood. His focus is the domestic New Zealand market. The article contains some excellent ideas.

However I suspect that the New Zealand farm blackwood resource will be more than enough to supply the local market, with the export market being much more significant for NZ growers, including the Australian market.

The export market will provide advantages that the NZ domestic market cannot, including:

  • markets for knotty blackwood timber that the NZ market cannot take;
  • strong price competition;
  • multiple markets and buyers looking for reliable supplies of premium grade timber;
  • access to high-value prestige markets such as the international tonewood market;
  • the well established Australian blackwood market in particular will be looking for alternative sources of blackwood timber, as supplies from Tasmania decline in the coming years.

I recently did a rough scoping study and calculated that New Zealand could be producing up to 10,000 cubic metres of premium blackwood sawlog per year within the next 5-10 years. Once markets, demand and price transparency become established, the feedback signals to farmers will quickly see the New Zealand blackwood resource expand further.

Perhaps Tasmanian farmers will then start to take notice.


NB. Thanks to the NZFFA for putting these two articles online allowing general public access.

Carrabin first thinning!

After my last visit to this plantation a few weeks ago I thought some urgent action was required so I offered to help with the thinning. My offer was accepted. So for the past two days I’ve been back up north helping to take this plantation to the next stage. See the following for previous blogs:

Over a day and a half we put 200 trees on the ground leaving about 100 trees still standing. A second, final thinning will be needed in 1-2 years to get the stand down to about 35 trees. The transformation over the last 2 days has been extraordinary! The plantation now looks fantastic. To the untrained eye it looks overthinnined, but in 2 years these crowns will have grown and filled in most of the gaps, and the trees will be putting on some serious wood volume.

The trees are developing some excellent heartwood. This picture shows the heartwood from two adjacent trees that were thinned. Same seedlot, same age. This is an extreme example of genetic variation in blackwood heartwood colour. The sample on the left is the more common golden brown blackwood colour and was the common colour found in this plantation. The sample on the right is a rare dark chocolate brown (if only we had known before we cut the tree down!). Both absolutely beautiful colours and indicative of what this plantation will produce in 20 years time. If only we could clone both of these colours. With a growers cooperative this could become a reality!


Having a close look at the plantation over the past two days it was obvious where the management could have been improved. Both the thinning and the pruning should have happened earlier. I don’t recommend planting 2,500 trees per hectare. But if that’s the way you want to go, then follow the New Zealand recommendation and prune to retain a minimum three (3) metres of green crown, ie. start clearwood pruning when the trees are 4 metres tall. By the time half of the trees have reached 6 metres tall you should be able to begin thinning. Pruning must be done while the trees (and hence branches) are still relatively small. Maximum diameter growth must be maintained so that pruning wounds heal as rapidly as possible (preferably within 12 months). By the time the trees are 10 metres tall the clearwood pruning should be completed. This should mean that most new pruning wounds are <3cm diameter!

This plantation has had it’s first thinning when the trees are 10-15 metres tall (far too late), and we were just completing the pruning while we were thinning! The thinning should have happened at least 8 years ago, and the pruning completed 5 years ago.

But lesson learnt. And it is still a huge credit to the owner. Easily one of the best blackwood plantations in Tasmania!

So the owners have a year’s worth of firewood to keep them warm, and their three happy goats and a small herd of cows are enjoying a major feed of blackwood greens from the thinnings.

The next tasks will be to mark and number the final crop trees and do a first measurement. Then in 1-2 years it will be a return visit for the final thinning. In 5 years time this plantation will look brilliant. A real inspiration to Tasmanian farmers. Thanks to the Carrabins for an excellent time.



Questions from a grower

Hi Gordon,

I think these are the sorts of questions that would interest potential and existing blackwood tree farmers. Maybe you could use them as the basis for a post on your WWW site?

a/ We have a range of blackwoods from just planted to some that are in the range 35-60cm+ DBH. The easiest way to determine their growth rate is to measure them over a few years but what would you say we should be looking at as annual DBH increment on these larger trees assuming it’s a good site?

If you are growing sawlogs that a sawmiller can process profitably then the traditional objective is to grow trees that have a diameter at 1.3 metres above the ground (what foresters call “breast height” or DBH) of 60 cm. Obviously not every tree in a plantation will be growing at exactly the same speed, so perhaps the goal is to have >80% of the trees in a plantation >60 cm DBH. Plantations are an investment, and return on any investment starts to drop dramatically once the investment is greater than 40 years. So growing a 60 cm blackwood over 40 years means an average annual diameter increment of 1.5 cm. I would put this as the minimum diameter increment for commercial blackwood. Now it might take a tree 5 years before it is growing at this speed, which means that for a few years at least it will have to grow a bit faster to get the 40 year average. Better still is to grow the blackwoods to 60cm in 30 years which would mean an average annual diameter increment of 2.0 cm.  Trees will only grow at this rate on good sites and only if they are well managed  ie. thinned to a 7 metre spacing. Exceptional trees will grow even faster than this, and in Chile and New Zealand they can get blackwood growth rates faster still.

If you are doing periodic diameter measurements one suggestion is to mark the stems of the blackwoods with a dab of spray paint so that you are measuring diameters in the exact same spot on the trees each time.

b/ We have a large amount of seed forming on our trees that we could use for direct seeding with some best tree selection. And my sister has some nice silver wattle and blackwoods on her property. What are your thoughts on direct seeding these acacias into some disturbed soil followed by some stem selection in the first few years? Perhaps ten or so seeds into a meter x meter.

Firstly I would ask what you are hoping to achieve by direct sowing that would be better than planting? If you are growing commercial blackwood I can’t see any advantage in direct seeding. In fact it adds complexity and extra effort. Compared to the New Zealand regime of spot spraying and planting at 3.5 metre spacings, direct sowing seems so much more work. For example weed control is always tricky with direct sowing once seedlings are growing, and weed control is essential in getting blackwoods growing quickly. Then there is all that thinning. No! In my opinion it would be better to use the seed by growing it in pots or tubes and planting at regular spacing. This makes management (pruning, thinning and weed control) so much easier.

Bye for now.

Thanks for the questions. I hope my answers provide you with the necessary information. Comments or further questions always welcome.

Happy blackwood growing!

Carrabin plantation update 2013

On my way back from the north west I called in on Giles Carrabin at Paradise to see how his plantation is going. I last reported on this plantation in March 2012:

This plantation is one of the few successfully managed blackwood plantations that I know of in Tasmania and is a real testament to the effort and dedication of it’s owner. It demonstrates a number of unique features including the successful use of shelter in a windy site. Three goats now help keep the weeds and blackberries under control (see the pictures).

The regime is not one I would recommend but full credit to Giles for making it work.

A start has now been made on thinning this plantation down to the final 30 trees (it’s only a small plantation). Already the retained trees are responding to the thinning with obvious crown growth. At least another 100 trees should be thinned from this plantation this season. With plenty of spring rainfall this will be a good growing season.

While a great success this plantation still faces two major management risks:

  • Thinning too slowly so that productive green crown is lost. Already some trees are beginning to lose their lower green crown due to increasing competition between the trees. These trees are losing their productive capacity, perhaps permanently. Thinning is critical to keep this plantation fully productive and allow the blackwood crowns to develop a stable wide structure.
  • Under thinning resulting in too many small trees that are slower growing. This is a common problem with farm plantations and Giles said he is already finding it hard. Having devoted so much physical and emotional effort to get the plantation to this stage it can be a real challenge to then have to cut down the results of so much effort. This is one reason I recommend a much simpler regime.

Having watched the Blackwood in New Zealand video, the risks of thinning too slowly and underthinning are very real. Poorly formed crowns (with the risk of future crown collapse), and permanent loss of growth potential are a high price to pay after so much effort. As farmer Ian Brown says on the video, beware of becoming too emotionally attached to your trees.

With continued good management this plantation will look fantastic in five years time and be a real inspiration to other Tasmanian farmers.

Giles is now planning to establish another plantation using a similar regime but with a wider (3x3m) planting spacing. With such a labour intensive regime I can only support this move to a lower planting rate.

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Quilliam plantation update 2013

A recent phone call from Jamie Quilliam meant a return journey to Circular Head for some blackwood pruning and maintenance. I last reported on this plantation in October 2012:

But compared to 12 months ago this visit was a completely different experience. A year ago, to my complete surprise, this plantation was showing plenty of potential for commercial blackwood growth despite many obvious challenges. But this year the trees looked pretty unhappy with none of the strong apical growth seen 12 months ago. Had I misjudged the site? Was all that strong early growth just a flash in the pan?

Potential issues are the rainfall (last season was a dry one so there wouldn’t have been so much growth), and weed competition (trying to control grass growth on these wet flats is a real challenge!)

The first day of pruning was under a howling westerly wind, which confirmed that at least one of the challenges here is exposure. Blackwoods don’t enjoy growing on exposed sites, not if you want them to grow tall and straight.

On the second day we had finished the pruning and Jamie offered to show me the 3 hectare remnant patch of swamp forest which is next to one of the blackwood plantings. This remnant bush had cattle grazing through it until 13 years ago when it was fenced off. Since then the forest has recovered surprisingly well. From a distance I could see some very impressive Eucalyptus brookerana. But what surprised me most was as we got closer I began to notice the magnificent swamp blackwoods, 25-30 metres tall with long straight trunks (see picture). Clearly this farm used to support some fantastic blackwood swamp forest.


I suggested to Jamie that he would have more success growing commercial blackwood by actively managing the remnant bush. There is some regeneration but also opportunities for active management (eg. controlling blackberries) and blackwood planting. The lessons learnt in actively managing the remnant bush might then help solve the problems in the blackwood plantation. Jamie wasn’t sure about this idea. He hasn’t reached the stage of being passionate about growing blackwood, not yet anyway!

Obviously shelter and nursing from the surrounding vegetation is an important factor in native swamp-grown blackwood. But has conversion to pasture completely destroyed the commercial blackwood growing potential of this property? Here is the perfect opportunity to find out. Side by side, plantation blackwood and high quality native blackwood swamp forest. From the outset I realised that this property was an experiment in the making. Can we find a way to grow quality commercial blackwood in plantations on this property?

The Sound of Business

A story posted yesterday on the Business Spectator website. One of their series on Australian family businesses. Not so much a story about blackwood, but given the importance of Melbourne-based Maton Guitars in the commercial development of blackwood as a internationally recognised tonewood I think it’s a great story. Plus I always enjoy reading Alan Kohler’s articles. Thankyou Matons and Mr Kohler.