You are here: Home» Membership» NZFFA Member Blogs» Shem Kerr's blog» Growing Trees in Hadley Cells – or Not

Growing Trees in Hadley Cells – or Not

Saturday, October 05, 2019, Shem Kerr's blog

“It's always the same
I'm running towards nothing
Again and again and again and again”

from A Forest by Robert James Smith / Simon Gallup / Matthieu A. Hartley / Laurence Andrew Tolhurst of The Cure

Note: this blog post and many others of independent thought can be found unedited at


Had a pack of Hadley cells dropped off up the track. Unwrapped them, and, Wow! What trees would be best to grow in these, and how? So, I read the information sheet [1]  Then went over the back of the section to plant some hickories: -the ones hockey sticks [2]  are made of - and mull over the ins outs hows whys and whens of Hadley cells, [3]  - which were quite a bit different from the slit side cells I'd been used to. When I got the hickories planted I decided it would be a good idea to plant some pecans I'd been offered. Pecan is a warm climate version of hickory and might make hockey sticks too [4]  and they're all nuts.[5].  Well, the spadework was tough going as it was pretty much new ground I was breaking down the back. It wasn't something I'd seen the local forestry industry take on. To do this you need to think outside the box.[6] Like Jenni, when I told her about Richard Bellman being lost in a forest, [7]  she said he should've just climbed a tree to get out.


(i) I want to grow some trees that would with minimum risk quickly and profitably produce hard naturally ground durable timber in and for uncertain climate change.

(ii) Now I had some Hadley cells at hand, I thought it might be worth seeing which species would be the most market-competitive grown in those.

(iii) I want to satisfy my curiosity about the market competitiveness of durability class 3 or 4 (D3 or D4) hardwood timber environmentally benignly ground retention treated with, say, refined bark products.

Method amidst the madness

Before even picking up a planting spade, a wise farm forester asks, Is the species worth growing? And, What are the risks?

Instead of deciding which is the most likely climate scenario, maybe my best choice would be to accommodate uncertainty and plant species that can handle just about everything you can throw at them: thrive with slightly warmer conditions in high climatic variability: drought, high humidity, intense rain events, wind, frost, heatwave, a lack of soil nutrients, or a more acid and unstable environment due to geo-engineering of the climate; resist bugs; and produce durable timber early in case of landslip, wind-throw, economics, or more extreme climate.

I took a hard long look at what others were growing and researching; and I did a literature search.

I also approached the subject knowing that naturally ground-durable timber had a unique market niche: a hole in the ground. While I could dig the hole now, the market was only going to exist after harvest and should last for at least 20 to 50 years into a time when the hole could be in a warmer climate and open to more severe attack by wood decay organisms. Another problem is that naturally ground durable timbers have variability in decay resistance; some species are less variable than others. Also, in a warmer (or colder) climate there might be market competition from faster growing, less durable species for use not in ground contact; or environmentally benignly ground-retention treated with something along the lines of refined bark products that would be available by harvest date.

I included options for the science deniers.

I selected the three species from the Specialty Wood Partnership [SWP] durable Eucalypt programme [8] ( E bosistoana; E globoidea; and E quadrangulata); three of the closest to ground durable from the informal Eucalypt Action Group's [EAG] “Stringybark” programme [9]  ( E sphaerocarpa; E acmenoides; and E microcorys); also a couple of others ; and I laid them on my technical decision-making table. I have included Cookson's [10]  ground durability data from Melbourne and Sydney as they both historically had similar rainfall and no termites, but different temperatures. The durability ratings are from AS 5604. Site preferences are from sources noted in the discussion.

                  Technical Decision-Making Table


Durability Class

Melbourne mar 920 mm

Sydney mar 950 mm

Innisfail mar 3500 mm

Min air temp establishment for amateurs

Site requirements for good growth

E bosistoana


>33.4 yrs

21.9 yrs

8.5 yrs


Fertile moist mod sheltered

E globoidea






P radiata type of sites

E quadrangulata






Moist clay very sheltered

E acmenoides


>33.4 yrs

27.6 yrs

21.9 yrs



E microcorys



32.6 yrs

23.9 yrs


Fertile moist mod sheltered

E sphaerocarpa






P radiata type of sites

E. paniculata







E laevopinea






P radiata type of sites

E punctata






Poor soil specialist

Robinia pseudoacacia






Fertile moist soil with shelter

Zelkova serrata (D2)       -25ºC Fertile moist soil with shelter


I also made a project governance table to sit at. On it I put the factors and the special considerations that govern whether a species is likely to have market competitiveness under climate change.


                   Project Governance Table 

Governing factors

Special considerations

Market competitive regimes/species; & risk

Global warming

High climatic variability

Short rotation Stringybarks (D1 to D3) in north

Ash group in south

Status quo

The usual issues

Stringybarks (D1 to D3) & Ash group

Regional cooling

Uncertainty & high climatic variability

Ash group & D3 Stringybarks

Average forestry soils

Disadvantages, species that need high nutrient status

Stringybarks in north;

Ash group in south

Fertile moist soils

Land use competition with food crops

Timberbelts of pecans, walnuts,

honey locust

Slow growing species

Climate risk

As timber-belts on relatively sheltered fertile

soil with reasonable separation from food crop

Close to urban centres

Competition for food & housing

As above: keep distance from buildings

Myrtle rust

Young trees and coppice most at risk

Lower risk- E acmenoides 73% healthy

E microcorys 70%

E globoidea 40% - Higher risk


Firebrands onto neighbours


Lower risk: Stringybarks, Ironbarks;

E microcorys .

Gums; Ashes- higher risk


Loose & airy fire bed of durable high energy twigs

Lower risk- short rotations;

- Higher risk- Long rotation-

permanent sinks &

Derelict stands



Lower risk E. sphaerocarpa;

higher risk E. quadrangulata.

Ice age

Seriously cold

Robinia; Zelkova; Populus; Salix; Betula



* [Includes Enhanced Cargo Cult Science [11] complete with SHOUTS LOUDER Tree Breeding Programme!!! [12]]

Concerning the forest industry's understanding of the importance of climate change: I found no reference to climate change in Morgenroth, et al [13] on species-to-site matching ; not in Salekin et al [14]  nor in Howe et al [15] in the 2017 SWP expert review  [grab this one before it disappears from view]; neither in the NZDFI Site-Species Matching Research Plan [16]

Poole et al [17] on the Potential for Growing and Processing Durable Eucalypts in New Zealand, -  with no reference to climate change,- made inferences to the the lack of climate suitability: “Some species such as Corymbia maculata, E.pilularis and E.microcorys are intolerant to frosts, particularly in the early years of establishment, until crown closure is achieved and the site microclimate is moderated. It could be that any species with natural habitat confined to north of Sydney will have a very limited range of potential plantation sites in New Zealand, which makes E.microcorys a problematic species.” I have sown E. microcorys seed in October; planted out in December; got canopy closure amongst a nurse crop before the first frost; grown and harvested it in an area that yearly experienced occasional -4o C air temperature. With skill, most stringybarks and allied species will perform well down to -4C: E. globoidea E. laevopinea & E. youmanii colder.

The New Zealand Dryland Forest Initiative Regional Strategic Plan Consultation document [18]  made reference to more severe drought using IPCC 5th assessment scenarios. “Climate change will bring hotter and drier conditions in the east of the country, with more frequent, and more severe, droughts(e.g. see (Niwa) [19] “NZ’s east coast faces increasing drought and high intensity storms due to climate change.” from Notes for visit to NZDFI trial at Rick Alexander’s property [20]  as well as “Species are adpted (sic) to climate change and trees can live for hundreds of years.” from NZDFI Regional Srategy 2019 [21]

Yes, Eucalypts are drought tolerant, but that doesn't mean they're profitable. They handle drought by shutting down least essential functions such as growing wood; so they can sit there doing nothing for hundreds of years: they can also be eaten burnt or blown over during that time.

The NZDFI  breeding research plan [22]   is “concentrating efforts and resources on breeding a few promising species that are drought tolerant and produce very durable heartwood in cool climates.” Enough said. I can put the SWP species as potential candidates for the regional cooling scenario.

It wasn't till I got to Piers Maclaren's unpublished and confidential 2004 critical review on realistic alternatives to radiata pine in New Zealand (available over there , which I'm not allowed to cite as a literature reference),- that I got to something approaching a risk assessment. Despite having been an author on the IPCC working group Piers doesn't mention climate change.

Ngugi et al [23]put together data which has serious economic implications for a dryland forestry initiative competing against plantations in moister climates.

Growing trees on silt or sand with rhizosphere access to a shallow aquifer isn't growing trees in dryland conditions. Hocking [24]  notes that E bosistoana doesn't do as well up on the dunes as it does on the moist sand below (on the area the cows have frequented). Yanjie Li et al [25] indicate similar good growth on alluvial soils with access to water.

Watt et al [26]  model forest productivity. One scenario has a 10% decrease in productivity for Pinus radiata in the north and at low elevations.

As noted by Satchell [27], [28] some class D2 and D3 durable Eucalypts already grow almost as fast as pine in the north, under climate change they may gain a competitive advantage over a wider range of sites. This might have implications for research allocations.

An increase in severe drought would be a stress factor for trees; and leave them more likely to be open to attack by defoliating insects than they might be otherwise. Lin [29] quantified the loss of productivity due to defoliation on E. bosistoana.

Gea and Shelbourne [30] note: “There is growing circumstantial evidence that the stringybarks, ... contain several species which are well adapted and have excellent sawing and solid wood properties, including natural durability.”

Mcneil comments in Satchell [31]  “Of the Eucs I grow the worst pest damage is on tereticornis, followed (more or less in order) by grandis, bosistoana, quadrangulata, saligna (all symphyomyrtus). Cladocalyx is disappointing, much more damage than I expected. E. cornuta is about the only symphyomyrtus that is more or less untouched. Ash group, stringys and microcorys are almost untouched.

Defoliation by insects shouldn't be a problem for Symphyomyrtus species provided that there is good species-to-site matching. The issue is that Symphyomyrtus will be mis-matched to sites because most NZ forestry sites are now or will in future be not stress-free or otherwise suitable for the ground durable Symphyomyrt species chosen by the SWP.

Lin et al 2016 [32] observed one generation of Paropsis charybdis in South Island plantations; and noted that two generations are often observed in the North Island. No connection yet to implication of a warmer climate or the possibility of three or more generations.

The DFI approach to tackling this issue is well summarised by Murray & Lin on page 46 of DURABLE EUCALYPTS ON DRYLANDS: PROTECTING AND ENHANCING VALUE Clemens M. Altaner, Tara J. Murray and Justin Morgenroth (Eds) WORKSHOP PROCEEDINGS 2017 [33] (download this gem before it gets edited) What I got out of it was the message that breeding selection for resistance to defoliation by insects could allow symphyomyrts to out-produce those from the subgenus eucalyptus. This conclusion is supported by Stone et al's [34] experiment on the first 3 years' growth of 19 out of 470 symphyomyrt species and 16 out of 108 species from the subgenus eucalyptus. Murray & Lin also point to the apparent shortcomings of the subgenus eucalyptus regarding pathogens; referring to Potts et al [35] laboratory experiment on 30 Tasmanian species [“Although substantial variation in eucalypt susceptibility to myrtle rust has been reported, screening of the 30 native Tasmanian species indicates subgenus Symphyomyrtus may be more susceptible than subgenus Eucalyptus (Potts et al., 2016). Consequently, generalisations about pest or pathogen resistance of a species should not be made based on its subgenus alone.” T.J.MURRAY & H.LIN ] The final sentence makes some sense (but not as a consequence of the argument presented previously).

Let me check if any of this applies to what I want to do. Now, I don't want to grow Tasmanian; non-commercial; or non-durable species; not in a laboratory; nor in Australia or any place overseas. From the approximately 470 Symphyomyrts I only want to grow one of the 19 “Symphyomyrt” species (actually it is from the subgenus Alveolata ) and none of the 16 (out of 108 ) subgenus Eucalyptus species experimented on by Stone et al; I definitely want to grow trees a lot longer than the first three years. I know that species from the subgenus Eucalyptus can be improved just as readily as Symphyomyrts. Here, I only want to consider the 3 SWP species; 3 from the EAG stringybark programme and possibly a couple of others, and grow the most likely candidates on a NZ hill country site with the prospect of climate change. And I want to reserve the most sheltered and richest dirt on my section for māra kai.. I also take it that the stringybarks have a narrower sap band, especially at younger age; also that they could have high productivity on less fertile sites, as could some symphyomyrts outside of the SWP/DFI programme.

Although it's greenhouse work, Zauza et al,[36] and Sandhu & Park [37]  give a more realistic appraisal of myrtle rust risk as it applies to ground durable species. It would appear that E globoidea isn't the best choice of stringybark.

In climate change, whether to warmer or cooler, there is greater climatic variability creating unpredictability in weather, making planting and growing food crops riskier, leading to crop failure. In times of climate change uncertainty and crop failure, migration increases and pressure is put on land resources. The argument that stringybarks are unsuitable for rich moist sites is irrelevant in this situation; just as it now becomes for E. bosistoana and E. quadrangulata. The stringybarks aren't in competition for high quality sites; nor are poor soil specialist symphyomyrts such as E. punctata.

Satchell [38]  notes the durability of thinnings: E. sphaerocarpa has good durability at a young age, while both E. quadrangulata and E. bosistoana don't. Further anecdotal evidence indicates that E. sphaerocarpa may be a better choice for a post or pole crop; also for short rotation forestry not only for naturally ground durable timber but also for high strength and appearance timber. Despite a species having been grown in NZ or “proved” itself over 100 years or more,- the requirements for special environments (fertile, or virtually wind free) plus lack of durability in young age trees are deciding factors in decisions not to grow such species.

Cookson's [10]  work shows faster rate of decay at Sydney (historical mean annual rainfall 950mm) than Melbourne with basically the same rainfall (920mm),- with no termite hazard on either site – 4 degree latitude difference, and >33% reduction in durability for E. bosistoana.

Page & Singh [39]  note that decay is faster in warmer, moist environments. Horticultural use will expose posts to pretty much the same soil moisture levels across major horticultural areas of NZ: global warming will give warmer holes. I include Cookson's service life measurements from Innisfail as an illustration of the potential of a black swan with termites. In general terms we can expect a lowering of durability as temperature rises. We could take an observed service life of a 20cm diameter D2 pole to have been around 30 years under late 20th century conditions in NZ: for trees planted now this durability is likely drop to <20 years if tropical expansion continues as some expect; or less if termites are introduced.

Despite the industry's lack of leadership, there exist individual EAG members pushing the leading edge of research for the foundations of a NZ Eucalypt industry that could prosper under climate change. The EAG is not a partner in the SWP.


I found within the NZ forestry industry and research community:

  • no evidence of formal practice or research into the concept of risk management of market competitiveness in naturally durable eucalypt timber either under or without climate change; and effectively nothing informally:
  • a lack of discussion on the land use implications of climate change;
  • nothing that would assist growers understand the financial risks of embarking on long term rotations of virtually untested eucalypt species in an uncertain climate;
  • poor understanding of practices that would assist establishment of trees in a sub-optimal climate that might change into an optimal one:
  • poor understanding of what causes or effects natural durability in eucalypt heartwood;
  • despite the extensive amount of documentation available on the SWP durable Eucalypt programme, and the millions of dollars spent by it,- no evidence of ISO 130000/ [40], or ISO 13010 , [41] criteria being used in it; nor of best practice in management and governance.
  • a lack of genuine appreciation and understanding of the EAG's leading edge ”stringybark” programme (even among its own members),- and how that model of research is the most fit for species-to-site & market-competitiveness matching under climate change. The EAG programme has been a victim of Brandolini's Law..

I came to the conclusion that having the industry gamble with our money by investing it in species that compete with food production; pandering to a niche market such as a hole in the ground; and ignoring the wider potential for productivity on forestry sites, couldn't be seen as the actions of a prudent person.

Whereas the EAG programme is rational sapient and the best way forward.


(as they appear: not alphabetical)

[1] Regional characteristics of tropical expansion and the role of climate variability. Christopher Lucas and Hanh Nguyen 2015


[3] H Nguyen, H H Hendon, E P Lim, G Bochat, E Maloney, B Timbol 2017 Variability of the extent of the Hadley circulation in the southern hemisphere: a regional perspective

[4] Before: The Honourable Mr. Justice Giaschi Oral Reasons for Judgment Mann v. Ball 2019 BCSC 1589

[5]Max Paschall 2018 Exploring North America's Oldest Food Forest

[6] Max Paschall 2018 Standards for Selecting Climate Resilient Trees in the Northeast

[7] Richard Bellman being lost in a forest,

[8] Specialty Wood Partnership [SWP] durable Eucalypt programme

[9] Eucalypt Action Group [EAG] “Stringybark” programme

[10] L. J. Cookson 2004 The In-ground Natural Durability of Australian Timbers

[11] Richard P. Feynman Cargo Cult Science Some remarks on science, pseudo-science, and learning how to not fool yourself. Caltech’s 1974 commencement address.

[12] Evolutionary Trade-Off between Vocal Tract and Testes Dimensions in Howler Monkeys
Jacob C. Dunn Lauren B.Halenar Thomas G.Davies JurgiCristobal-Azkarate David Reby Dan Sykes Sabine Dengg W. Tecumseh Fitch Leslie A.Knapp

[13] Morgenroth, J., Lausberg, M., Millen, P., Mason, E., Meason, D., Dungey, H., Evans, M. 2016. A regional approach to matching specialty timber species to sites. Specialty Wood Products Partnership.

[14] Serajis Salekin, Justin Morgenroth, Euan Mason 2017 Modelling growth of Eucalyptus spp. on New Zealand dryland micro-sites

[15] Glenn Howe, Kevin Harding and Andy Buchanan: Expert Advisory Panel review of the SWP programme -2017

[16] NZDFI Site-Species Matching Research Plan

[17] Barry Poole, Gary Waugh & Jun Li Yang 2017 Potential for Growing and Processing Durable Eucalypts in New Zealand

[18]NZDFI 2018 Consultation Paper: Durable eucalypt forests:A multi-regional opportunity for investment in NZ drylands

[19] NIWA Climate change scenarios for New Zealand

[20] NZDFI 2016 Notes for visit to NZDFI trial at Rick Alexander’s property

[21] NZDFI 2019 Regional Stratagy: 2020 to2030 Durable Eucalypts A Multi-RegionalOpportunity for New Zealand’s drylandsFocus Areas and Action/Goals for 2019-2022

[22] The NZDFI breeding research plan

[23] Michael R Ngugi, David Doley, Mark Cant & Daniel B Botkin 2015 Growth rates of Eucalyptus and other Australian native tree species derived from seven decades of growth monitoring

[24] Denis Hocking, Alleviating the boredom with eucalypts New Zealand Tree Grower November 2008.

[25] Yanjie Li · Luis A. Apiolaza· Clemens Altaner Genetic variation in heartwood properties and growth traits of Eucalyptus bosistoana in European Journal of Forestry Research June 2018

[26] Michael S Watt, Miko U F Kirschbaum, John R Moore, H Grant Pearce, Lindsay S Bulman, Eckehard G Brockerhoff, Assessment of multiple climate change effects on plantation forests in New Zealand 2018

[27] Eucalyptus laevopinea for high value hardwood Sunday, May 25, 2014

[28] Lost durable eucalypt trials, Northland Saturday, May 24, 2014, Dean Satchell's blog

[29] Huimin Lin : Risk and Impact of Insect Herbivores on the Development 0f Dryland Eucalyptus Forestry in New Zealand

[30] Luigi Gea and Tony Shelbourne, Eucalypt species trials in the Wairarapa and Hawke’s Bay New Zealand Tree Grower November 2006

[31] Mcneil comments in Satchell

[32] Huimin Lin Tara Murray Euan Mason 2016 Population Dynamics of Four Insect Defoliators in a Dryland South Island Eucalyptus plantation

[33] Tara Murray & Huimin Lin on page 46 of Managing insect pest risks for durable eucalypts in New Zealand: optimised monitoring and selection for tolerance. in DURABLE EUCALYPTS ON DRYLANDS: PROTECTING AND ENHANCING VALUE Clemens M. Altaner, Tara J. Murray and Justin Morgenroth (Eds) WORKSHOP PROCEEDINGS 2017

[34] Stone, C., Simpson, J. A. & Gittins, R. 1998. Differential impact of insect herbivores and fungal pathogens on the Eucalyptus subgenera Symphyomyrtus and Monocalyptus and genus Corymbia. Australian Journal of Botany,46,723-734

[35] Potts, B. M., Sandhu, K. S., Wardlaw, T., Freeman, J., Li, H. F., Tilyard, P. & Park, R. F. 2016. Evolutionary history shapes the susceptibility of an island tree flora to an exotic pathogen. Forest Ecology and Management,368,183-193

[36] Edival A. V. Zauza, Acelino C. Alfenas, Ken Old, Michelle M. F. Couto ,Rodrigo N. Gra¸ca and Luiz Antônio Maf?a Myrtaceae species resistance to rust caused by Puccinia psidii Australasian Plant Pathology, 2010, 39, 406–411

[37]Dr. Karanjeet Sandhu and Prof. Robert Park 2013 Genetic basis of pathogenicity in Uredo rangelii

[38] Eucalyptus sphaerocarpa, my favourite durable timber species Saturday, December 20, 2014, Dean Satchell's blog

[39] Page & Singh



No posts yet

Disclaimer: Personal views expressed in this blog are those of the writers and do not necessarily represent those of the NZ Farm Forestry Association.

Farm Forestry - Headlines

Article archive »