Farm Forestry New ZealandEucalyptus selection for New Zealand - what is the elephant in the room?
Thursday, November 10, 2016, Dean Satchell's blog
We each grow forest plantations for a reason. Those reasons may vary, but my primary reason is for a return on my investment. This means producing wood or fibre as fast as possible from trees that remain healthy throughout their rotation.
I'll be so blunt as to state that the most important factor to consider when selecting eucalyptus species for commercial forestry in New Zealand is forest health. I state this categorically and from experience.
The problem for growers in New Zealand is that each new pest that "blows across the ditch" from Australia adds to the pest load and eventually the burden gets too much. Serious pest attack on forestry plantations can be devastating and many of us have seen it. However, where this gets interesting is in species selection for insect resistence. Each new pest that arrives favours certain eucalypt species. Just some. Never all eucalypt species. Most people lose interest at this point because there are just so many species of eucalypt... and there are now so many pest species that it all becomes too complicated ...and so the grower exclaims that eucalypts are bug fodder and throws in the towel.
However, this is not quite an accurate summation. Let me explain why. The key to understanding it all is to divide eucalypts into two groups: "Monocalypts" and "Symphyomyrts". I'm not going to go into taxonomical details about what separates these two groups, but what I am going to show you is black and white. What observant growers have begun to notice in New Zealand that could give us the edge globally on growing eucalypt plantations.
The edge you ask? How could that be... we're getting all the pests and euc's don't grow here any good. Look at Brazil I hear you say, they can bloody well grow the things in ten years or less! No pests over there... too far from Australia. Well... I would suggest that this is changing with world trade the way it is. It is only a matter of time before South America, Asia, Africa and Europe will also provide a green salad smorgasboard for a plethora of these Australian eucalypt munching pests. So what species are they all growing? Symphyomyrts. Why? Because symphyomyrts have faster early growth than monocalypts (we all love early growth, don't we). Commercial eucalypt plantations throughout the world are almost exclusively Symphyomyrtus species. Indeed we started out that way in New Zealand and planted lots of blue gum (Eucalyptus globulus) over 100 years ago because it grew so well. Unlike the rest of the world however, the eucalyptus tortoise beetle Paropsis charybdis then arrived and saw to our blue gum plantations. Chewed the shit out of them, so we gave up. The same thing is beginning to happen in other countries.
At this point I have to say we're a resilient lot, us New Zealanders, and there are always crackpots who are willing to try something else. Lots more euc species just over there in Australia, with planters willing to give any of them a go. What emerged eventually, from decades of trial and error, has been consistent and compelling... the species that grow best here are the monocalypts. Took a while for many of us to realise, and some still doggedly perservere with symphyomyrtus species because of fast early growth or desired wood properties such as colour or durability. But with the arrival of each new pest species, the list of starters gets smaller and smaller.
Unless you see the light, you're on a sinking ship. Believe me. Monocalypts don't get the bugs like the symphyomyrtus species, we've known this for some time (see here and here).
The monocalypts could be said to be "ordinary". Their timber is not particularly colourful, nor highly durable... but the wood is durable enough and colourful enough for most applications. Their early growth is quite ordinary by international standards, but what we've discovered is their resilience. They've brushed off everything that Australia has thrown at us and grow pretty much as well as they always have. Their lack of fast early growth is made up for by solid, consistent growth over the medium and long term (similar to radiata but slower than Brazilian eucalypts). The monocalypts are well adapted to moderate fertility and free draining sites in the same way radiata pine is. There is no doubt whatsoever in my mind about their commercial potential. Their timber is stable and easy to mill and dry. The sapwood band is consistetly narrow and the defect core is small.
Lets have a look at some serious pest introductions and their favourite tucker:
Eucalyptus Variegated Beetle (EVB) Paropsisterna variicollis
Serious damage: E. bosistoana, E. tricarpa, E. cladocalyx (all Symphyomyrtus)
Little to no damage: E. muelleriana, E. globoidea, E. macrorhyncha, E. eugenoides, E. pilularis, E. fastigata, E. obliqua, E. regnans (all Monocalyptus)
Bronze Bug, Thaumastocoris peregrinus
Serious damage: E. camaldulensis, E. grandis (all Symphyomyrtus)
Little to no damage: E. muelleriana, E. globoidea, E. macrorhyncha, E. eugenoides, E. pilularis, E. fastigata, E. obliqua, E. regnans (all Monocalyptus)
Brown lace lerp, Cardiaspina fiscella
Serious damage: E. saligna, E. botryoides, E. robusta, E. grandis (all Symphyomyrtus)
Little to no damage: E. muelleriana, E. globoidea, E. macrorhyncha, E. eugenoides, E. pilularis, E. fastigata, E. obliqua, E. regnans (all Monocalyptus)
Eucalyptus Tortoise Beetle Paropsis charybdis
Serious damage: E. globulus, E. quadrangulata, E. grandis, E. scias, E. nitens, E. camaldulensis, E. longifolia, E. macarthurii, E. leucoxylon (all Symphyomyrtus)
Little to no damage: E. globoidea, E. macrorhyncha, E. eugenoides, E. pilularis, E. fastigata, E. obliqua, E. regnans (all Monocalyptus)
You should start seeing a picture emerging. Each new pest arrival has an appetite for some of the symphyomyrts, but not all. But as they keep coming all the bases eventually get covered.
The question I am asking and one I would appreciate some feedback on below, is at what point do we say enough is enough, see the light and stick to planting monocalypts?
Footnote: Monocalyptus species include E. regnans, E. obliqua, E. fastigata (Ash group), E. pilularis, E. sphaerocarpa, E. globoidea, E. muelleriana, E. laevopinea, E. macrorhyncha (Stringybark group).
Disclaimer: Personal views expressed in this blog are those of the writers and do not necessarily represent those of the NZ Farm Forestry Association.
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2 posts.
Post from Mike MacFarlane on January 6, 2017 at 1:42PM
A very interesting article thanks Dean. I planted a block back in 2002 that included euc obliqua and euc regnans and they are doing very well despite the worst drought in the Hurunui since at least 1931 (which is how far back my rainfall records go). The reason I chose those euc species was becuase the original landowner (John Caverhill) planted obliqua and regnans back in the 1800's and they did very well. We still have some that exceed 100 years of age that are up to 50m in height.
Thus far ("touch wood") the pest and disease load has been minimal. I milled a large amount of obliqua plus some regnans for my house and used it for board and batten cladding, exterior decking and also internal T&G flooring and the results were fabulous. The obliqua has a rich honey colour and the odd resin pocket adds interest to the flooring. We also used obliqua for the cattle yards and many other projects. I am a big fan and found very few issues with it in terms of milling and lumber- a bit of end checking and some minor washboarding that easily planed out.
My formula was to mill large, mature trees,green (we used a portable bandsaw), We quarter sawed to help with stability, and also applied wax emulsion to the ends of all planks. We strip stacked in the open shed (shade cloth) with fillets spaced 1 metre apart to air dry to around 13% moisture, then to the de - humidifier at 45 degrees to get it below 12%, then it was machined and a natural oil stain was applied before use.
Post from Shem & Jen Kerr on April 25, 2018 at 3:19PM
Putting aside the statement that monocalypts are not particularly colourful, nor highly durable as incorrect: [ those Northland trial wonky E pilularis should mill up with real interesting grain, and colourful around large knots; E acmenoides is rated as D1] any chance that elephant is the one from the parable of the visually impaired foresters elephant?
We planted some eucalypts/monocalypts; and even more symphyomyrts. But the only eucalyptus that got close to millable size and were milled were the alveolatas/nothocalypts: every single species.
In round 2 we're on a site with more diverse soil texture & moisture. We want to only plant highly productive species that grow good appearance stiff ground durable timber early; process easily; have market versitility; and that lack fire-lighter sheets of bark hanging from the branches and truck. A few of the monocalypts tick all the boxes . E microcorys can do the job on moderately rich soils that retain some moisture much of the year. What can the symphyomyrts do for us? We checked out how the neighbours' forest was doing. The symphyomyrts whether ground durable or not weren't in the race. With all the research funding being spent on them, sure hope there's a place for ground durable symphyomyrts.
Maybe on frostier drier sites that are seasonally puggy then brick hard where anything would have slower growth rates: after some breeding work to deal to the bugs; and improve the wood qualities and growth rate: there could be a (not to be sneered at) niche for on farm timber from say E bosistoana in 40 to 60 years time. Once you cut out the costs of the market the economics become more attractive. It might even stretch to local community use. However, we're having trouble feeling the competitiveness of dryland production for the wider market when up against close by wetter areas. The D2 rated monocalypt E globoibea grown on a fertile well watered site can last 30 to 35 years in ground. There's a significant area of suitable land between and inland of Bulls and Pukekawa on which such a monocalypt will grow durable timber in less than half the time that a symphyomyrt will do any where in NZ. There are a number of West coast North Island ports for barging logs to the South island. The elephant in the room is likely to be the economics of growing symphyomyrts.
About that elephant from the parable: feel the deluge: is it the breaking of the waters before the imminent birth of a vibrant timber industry based on the subgenus symphyomyrtus; or are all those research funds merely producing a lot of very expensive urine? The elephant feels kind of like THE WALKING DEAD? ZOMBIE FIRMS AND PRODUCTIVITY PERFORMANCE IN OECD COUNTRIES
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