Benefits of exotic conifers

This post extracts choice bits from ‘The Ecological, Environmental and Economic Benefits of Exotic Conifers‘ by Owen Springford (BFSc) published in which is gratefully acknowledged. Please visit to read a great deal of useful information.

Note: Hieracium is commonly known as hawkweed. Minor typographic corrections applied.

“Conservation will only ever be second fiddle to the other priorities of the Government of the day. Consequently, the status quo, comprising the neglect of 80% of the conservation estate, will continue with large numbers of taxa nudging ever closer to extinction.”

“Wilding forests could hold the key to an unprecedented restoration of native flora and fauna in the Department of Conservation (DoC) estate and beyond. However, it comes with the requirement for major shift in thinking by the both Government and DoC. Firstly, the Government needs to ring-fence revenue earned from the conservation estate to the maintenance and improvement of the estate rather than all monies going to the consolidated fund as does now. Secondly, DoC will need to change the deeply ingrained ideology that it has in respect of the place of forests containing non-indigenous species.”


“The critical agents that conspire against native forest succession and retention are; grazing animals, the animals that destroy the birds that disperse forest species, and exotic grasses. Exotic grasses are particularly antagonistic to native forest species for two reasons. They support grazing animals and the mycorrhizae (root fungi) associations of grasses appear to be highly effective at preventing native forest species to grow, …”

“Under a healthy native forest ecosystem, if exotic conifers are present, they have great difficulty continuing with succession. This is because they are not specifically adapted to the NZ environment. When they do persist then there is invariably some ecological agent involved for example high pig populations that till up the soil and allow these exotics to re-seed.”

“Many exotic conifers that are in NZ evolved to exploit the opportunity created by the retreat of the North American ice sheets before soils had formed and in the presence of grazing animals. In NZ, these exotic conifers have found a situation that closely resembles the environment they evolved in. A situation created by a century and a half of gross land mismanagement. These conifers then set about to undo this damage by firstly increasing soil carbon or organic matter in the soil. … the exotic conifers build a cradle for fertility and then fill that cradle with nutrients.”

“Walking through these areas, especially in spring, it is clear to see the halo of fertility that is developing around each tree with exotic grasses and clover growing. Native birds, particularly fantails, are quick to occupy young exotic wilding forests, generally followed by bellbirds and robins. Once the populations of these birds reach high levels, NZ falcons start to turn up. Native forest species then start to appear in the developing forests. The speed of this process depends on the location of seed sources and the populations of native birds.”

“In stark contrast to exotic grassland, native forest species are successful colonisers in exotic conifer forests, presumably because exotic forests resemble the ecosystems that those species evolved in. In the fullness of time, exotic forest will succumb to native forest succession subject to two conditions; the control of grazing and the control of the pests that predate native birds – an important point for the future management of these forests. While these self-generating exotic forests are a symptom of a severe problem, they provide the solution in that they restore the life-giving capacity of the land.”


“Compared to the near ecological desert that exists under degraded rangeland farming that has developed into a sea of Hieracium, wildings create microclimates with large volumes of living space for all manner of native flora and fauna, much as a coral reef provides diverse opportunities for all manner of creatures to live. A hectare of Hieracium with a canopy of say 5 cm provides a living space volume of 500 m3 per hectare while a 30-metre conifer stand provides a living space volume of 300,000 m3/ha. Native birds and bats need trees as a place to make defendable nests and the older the trees the better.”


“Conifers are incapable of colonising healthy grass ecosystems. However, in the situations where overgrazing and burning have done so much damage to the land that it can no longer support grazing, this then provides the opportunity for self-generating exotic trees to develop.”


“Wildings develop on land where other possibilities no longer exist. Wilding forests themselves create a fantastic option and economic opportunity, specifically under the Emissions Trading Scheme. The average sequestration rate for Exotic Softwoods … is 12.8 tonnes CO2 equivalent per ha per year over 50 years. However, there have been measurements … that show wilding stands with sequestration rates more than 5 times that rate. … wilding forests provide the best hope for NZ to meet the Government’s currently stated goal of a net 5% reduction on 1990 emission levels by 2030.”

“NZ has one of the highest per capita emissions profiles in the world after the US, Canada and Australia (excluding the Arabian Gulf states which are in a league of their own). Wildings provide perhaps the last chance for NZ to salvage its “Clean Green” image which is now failing to pass the smell test.”


“In their native state, the wilding conifers grace some of the most beautiful landscapes on earth, the Rocky Mountains of North America. So the forests are not inherently ugly. Few tourist photos of Mt Cook are not framed by wilding forests. The argument then goes that these forests are not natural to NZ. However, these forests only develop in areas where the existing native vegetation has largely been destroyed so those landscapes can hardly be described as being “natural”. As a forester with 35 years experience, I’ve never seen an example of exotic conifers taking over a healthy native forest ecosystem. … The shortest book in NZ would be called “Native Biodiversity on a Dairy Farm”.


“DoC is flying in the face of Mother Nature who is desperately trying to reclothe herself after a century and half of abuse. Rather than fight Mother Nature, the strategy should be to work with her by encouraging wilding forest to develop and then promote the succession of native forest within these wilding forests. The wilding forest could fund these management operations through revenue from the ETS. The use of wilding forests could lead to the greatest native forest regeneration project since the Taupo eruption and revenues from these forests could be used to fund protection of the rest of the native forest estate of which over 80% is wallowing in a disgraceful state of near-total neglect.”

Save our kauri – expert evidence

We’re grateful for permission to publish this important Expert Evidence from Dr Cate Macinnis-Ng regarding kauri.

The text follows. You may download the PDF here.

13th February 2020

Qualifications and experience

  1. I am a plant eco-physiologist and eco-hydrologist and am an Associate
    Professor at the School of Biological Sciences at the University of
    Auckland. I measure and model carbon and water cycling in forests and
    am particularly interested in the effects of global change processes (like
    climate change and land use change) on forests and other vegetation.
  2. I received my PhD in 2003 from the University of Technology Sydney
    (UTS). I worked at UTS for seven years as a research fellow
    researching water use of vegetation in several research groups
    including the National Centre for Groundwater Research and Training. I
    have published 46 peer-reviewed journal articles and I have written nine
    technical reports.
  3. Since moving to New Zealand in 2010, I have been working on the
    physiology of kauri. In 2012, I received a Marsden Fund Fast-Start grant
    from the Royal Society of New Zealand to study the water use patterns
    of these iconic trees. In 2014, I was awarded the Early Career
    Research Excellence Award at the University of Auckland and in 2015, I
    was awarded a Rutherford Discovery Fellowship by the Royal Society
    of New Zealand.
  4. I have been asked by Save Our Kauri Trust to provide an assessment
    of the impact of the proposed water treatment plant on protected land
    bordered by Woodlands Park Rd, Manuka Rd Titirangi.
  5. I advise that I have read the Code of Conduct for Expert Witnesses
    contained in the Environment Court Practice Note 2014 and have
    complied with it in preparing this evidence. I confirm that the issues
    addressed in this evidence are within my area of expertise and I have
    not omitted material facts known to me that might alter or detract from
    my evidence.
  6. In this document, I outline the value of the established ecosystems as
    an essential part of the landscape and a valuable carbon store.
  7. Generally, forests provide us with many goods and services that
    support human life. Forest products include wood and gum (these are
    often referred to as ecosystem goods). The value of these goods can
    be easily determined based on market prices.
  8. Ecosystem services are more difficult to value because they are less
    tangible. Carbon uptake and storage is a good example of a forest
    ecosystem service. Forests absorb CO2 as they grow and trees store
    this carbon in their stems, branches, leaves and roots. Forests also play
    an important role in the water cycle as transpiration is one of the major
    pathways through which water returns to the atmosphere after rain.
    Trees are important for flood mitigation because they collect rainfall on
    their leaves and buffer water flow through the landscape. Tree roots are
    also important for binding the soil and preventing erosion.
  9. Kauri forests are particularly valuable because they are amongst the
    most carbon dense forests in the world. A single tree can store vast
    amounts of carbon and will also use large volumes of water each year.
  10. The trees within the proposed area to be felled are not particularly large
    but as there are hundreds of trees to be removed, collectively their
    carbon storage is considerable. Under a climate emergency, all effort
    should be made to protect established forests for the rich carbon
    reserves they store both above and below ground.
  11. There are several kauri trees of a relatively young age at the site but as
    kauridieback is killing hundreds of trees, all individuals should be
    protected because we don’t know which tree will be the future Tāne
    Mahuta centuries from now. Ongoing work by one of my PhD students
    is just beginning to unravel the physiological responses of kauri to kauri
    dieback disease. Disturbance of the site will likely spread the pathogen
    due to soil movement by euqipment and hydrological changes due to
    removal of trees. Established canopy and root systems provide
    protection of the soil by reducing water reaching the understorey and
    binding the soil as described below.
  12. During a rainfall event, a large canopy of leaves will capture water until
    the leaf surfaces have been saturated. This process is known as
    ‘wetting up’ and it reduces the amount of water reaching the ground
    because the water stays on the leaves until it evaporates once the rain
    has cleared. A closed canopy is likely to have a leaf area of 3-4 m of
    leaves per unit of ground so this surface area has a significant effect on
    the water cycle.
  13. Detailed measurements of rainfall redistribution in kauri forest by
    Sangster (1986, unpublished MSc thesis, University of Auckland)
    showed interception loss was 44% of incoming rainfall. This is
    consistent with other similar forest types around the world and indicates
    that only 56% of rainfall reaches the forest floor. Removal of trees
    therefore increases water input onto the land surface and increases
    water logging and runoff. More runoff can mean more erosion and more
    frequent and severe floods in addition to movement of soil, potentially
    spreading kauri dieback.
  14. Tree roots are also important for binding soil. Where there is
    complicated topography, established trees are important for stabilisation
    of any slopes. As a rule of thumb, a tree stores half its biomass above
    ground and the other half below ground so the root systems of the
    vegetation proposed to be removed would be very large.
  15. There are several notable larger kauri in the vicinity of the area
    proposed to be cleared. We are just learning how trees interact below
    ground through the rhizosphere. In addition to my concerns about soil
    movement due to earth work equipment and water flow, I am also
    concerned that the root systems of these trees will be adversely
    impacted by the vegetation removal. Significant trees need substantial
    buffers for best protection.
  16. Any proposed biodiversity offset will not be a meaningful replacement in
    a changing climate. Established forests are better placed to survive
    drought because they have deep root systems to access deep water
    stores. Seedlings and saplings do not have adequate root structures to
    allow them to survive dry periods. Under the current drought conditions,
    we are seeing restorations plantings completely fail across the city
    because the deveoping soil moisture deficit is killing sensitive seedlings.
    As droughts are predicted to become more frequent and severe, we
    cannot predict if on offset planting will survive to a mature age.
    Established forest has never been more valuable for the carbon it
    stores, the water it regulates and it’s ability to survive drought.

Adopt a tree

Adopt a Tree: an open-air festival in praise of trees, Western Park, Auckland.

Tie a Yellow Ribbon Around Your Adopted Tree 18 November 2017

On 18 November 2017, the Urban Tree Alliance (Wendy Gray, Aprilanne Bonar) ran the Adopt-a-Tree community event kicking off the public awareness campaign at Western Park, Auckland.

Supported by Waitematā Local Board and local businesses, the event offered live music, face painting, forest bathing, taiji and yoga classes, tree meditation.

The campaign invites Auckland residents to adopt their favourite tree locally, get to know it, give it a drink particularly in the hot summer months and remind construction workers to be careful around trees.

Free yellow ribbons were handed out on the day for members of the public to tie around their chosen tree.

In the last 4 years (in 2017) one third of Auckland’s urban canopy has been cut down and by 2030, if the status quo exists, there will be no urban tree canopy left in Auckland.

Here are some memories of the festival. We hope to be organising soon. Let us know if you're interested in being involved, or running one events.

© Tom Ang

The flyer advertising the event.

Adopt a Tree flyer

Tree consciousness

Tree consciousness expands life with joy.

Consciousness of trees is to living – as fresh air is to breathing

You can go through your entire life without ever thinking about your breathing. You could be hardly conscious of it even though you breathe every minute of your life. You won’t die on the spot if you stop thinking about your breathing. That’s because your body has amazingly precise and automatic systems for making sure you keep breathing and stay alive.

You can also go through your entire life without ever thinking about trees. You could be hardly conscious of them, even when you walk past them. And you certainly won’t die on the spot if you never ever think about trees! But that’s only because trees are working every daylight minute to give you the stuff that keeps you breathing.

Life in breath

Think what wonderful things become possible once you become fully conscious of breathing. Life is enriched as whole worlds open up. Conscious breathing powers all theatre from singing to acting to dancing to performing music. Without great breathing, sports and martial arts are closed to you. Breathing is also the key to all kinds of mind-body practices like yoga, meditation.
You may not think you’re conscious of trees. But on very hot, sunny days do you instinctively enjoy leafy shade when you get under it? Do you duck under a tree’s cover then you’re caught out in a rain bomb? Have you ever noticed that if you’re in a bad mood, a walk under some trees always makes you feel better?

Tree conscious

When you become fully tree conscious, something wonderful happens. It’s like suddenly appreciating someone who has always been there for you. They’re there in the background and you don’t see them. Yet you can always rely them. Trees have been in the background – yours, mine, everyone’s – from the first day any of us were born. We kicked the leaves when we were little, We had picnics in their shade. We watched birds flying in and out.

When you become tree conscious, you appreciate how they soften the harsh lines of the city. How they give colour through their leaves and flowers. How the movement of the leaves refreshes your eyes, their rustling provides a soft music that always soothes.

As you become more aware of trees, you remember what you learnt at school. Trees produce a truly vital thing we need to stay alive. Oxygen. Without it, you can’t breathe. Actually, you’d die in seconds. The leaves of trees churn out oxygen every daylight minute of every day – without pause or let up – all year round. A fair-sized mature tree produces roughly enough oxygen to keep a family alive.

Awhi-awhi, a female kauri (Agathis australis) in Waitakeres, on death row operated by a developer.
Air of life

Yes; that means for every tree that is cut down, there is several fewer people the planet can keep alive. At present, the air is on average about 20% oxygen and we can live comfortably with that. But in cities the proportion of oxygen in the air drops to as low as 17% and in crowded indoor space, even less. At around this level, people get irritable, cross, uncomfortable and feel more stressed as levels drop.

Globally, oxygen levels are dropping. But in localities like a forest, oxygen levels can rise to 21% and greater. Little wonder we all feel more chilled out in a forest than in a high street.

But not only do trees produce the oxygen you need to live. Just like appreciating all the quiet things a supportive person does for you, tree consciousness opens up all the invisible services trees render. We enjoy their shade and shelter from the rain. But that shelter also protects the ground: trees soften the eroding effects of rain by retaining vast amounts in the leaves before letting it drip steadily to the ground. Trees control storm water by soaking up thousands of gallons. They break up strong winds and also dissipate noise. Tree leaves also filter the air, collecting dust particles to be washed later by rain.

Unseen life

Then there are the other creatures that share trees with us. We see the most obvious – the birds – but few of us take notice of the insects and small plants that depend on a tree. And we’d do well to pay attention to the massive life underground. Literally massive. As much, if not more, of the biomass of a tree lies underground. And with it all the soil myccorhiza and fungi and bacteria that enable a tree to extract minerals from the soil. An armful of healthy soil could contain 3 kilometres of fungal hyphae or threads that move water and minerals between plans, between trees.

Less than 1mm long, millions of springtails like this Onychiurus keep the soil healthy.

It offers shelter and home to dozens of species of insects which are food for birds, pollinate our flowers, and clean up our environment by eating up our waste. And there will be lichen, fungi and plants growing on the trees. Some you can see, some you won’t spot. But one thing you can guarantee: there’s no such thing as a tree that’s empty of life.

Tree consciousness unwraps a world that you knew only by its superficial coverings.

Tree consciousness deepens your appreciation of the intricate web of all living things, their inter-connectedness, their inter-dependence. Above all, tree consciousness deepens your appreciation of how you – and everything you hold dear – all depend, and depend totally, on trees. Tree consciousness brings you to feel a deep gratitude for all that trees give to us. And that can only enrich your living.

Tom Ang : April 2018

Maunga and The Reserves Act

TMA has failed in its duty under The Reserves Act.

A brief note on the relation of Tūpuna Maunga Authority (TMA) activities to The Reserves Act. And its failures.

1. The Reserves Act 1977 is administered by Department of Conservation.
2. Ngā Mana Whenua o Tāmaki Makaurau Collective Redress Act 2014 (Redress Act) refers repeatedly to Reserves Act in Part 2: essentially, it revokes the Act for each maunga, then transfers fee simple to TMA.

3. Redress Act Part 2: Cultural redress: § 17 Statement of Association says: (1) The Crown acknowledges the statements of association of iwi and hapū.(2) However, the statements—(a) must not affect, or be taken into account by, a person exercising a power or performing a function or duty under an enactment or a bylaw made by a local authority under an enactment; and (b) do not affect the lawful rights or legal obligations of any person; and (c) do not grant, create, or affect any interests or rights relating to the lands referred to in the statements.(My emphasis: that’s why we can protest on ‘their’ land.)

4. Subpart 1 goes through the vesting of maunga (other than Maungauika and Rarotonga) for each maunga.
5. In each §, after the fee simple of each is vested in the trustee (TMA), each maunga is “then declared a reserve and classified as a XXX reserve subject to section YY of the Reserves Act 1977.” XXX refers to the reserve being either a a local purpose reserve, historic reserve, or recreation reserve. According type of reserve, different sections apply: respectively 17, 18, 23. Some maunga have more than one type of reserve.(There’s also a clause for easement for Watercare.)

6. The germane bits are: § 17 ‘Recreation reserves’ stipulates: (2) (b) that “every recreation reserve shall be so administered under the appropriate provisions of this Act that … where scenic, historic, archaeological, biological, geological, or other scientific features or indigenous flora or fauna or wildlife are present on the reserve, those features or that flora or fauna or wildlife shall be managed and protected to the extent compatible with the principal or primary purpose of the reserve… and (c) those qualities of the reserve which contribute to the pleasantness, harmony, and cohesion of the natural environment and to the better use and enjoyment of the reserve shall be conserved (d) to the extent compatible with the principal or primary purpose of the reserve, its value as a soil, water, and forest conservation area shall be maintained.”(My emphases.) (Ōwairaka is a recreation reserve)
7. § 18 ‘Historic reserves’ uses essentially the same wordings, adding protections of historical sites. It adds (e) except where the Minister otherwise determines, the indigenous flora and fauna and natural environment shall as far as possible be preserved … (My emphasis.)

8. § 23 ‘Local purpose reserves’ makes similar requirements regarding managing and protecting biological or natural features, conserving forest etc.
9. Note that Maungakiekie northern land and Māngere Mountain are administered lands meaning the Crown owns them, but TMA administers them for purposes of Reserves Act.

10. Whole point is: TMA has failed in its duty and obligations pursuant to § 17, 18, 23 of Reserves Act 1977 in respect of Ōhiuarangi, Mangere Maunga and Maungarei in that TMA has (a) destroyed the pleasantness, harmony and cohesion of the natural environment of these maunga by their indiscriminate and insensitive felling operations, (b) harmed irrevocably the use and enjoyment of the reserves (c) damaged their value as soil, water and forest conservation areas through felling and failure to revegetate(d) destroyed flora, fauna and wildlife through indiscriminate felling of trees and insensitive, polluting planting practices(e) destroyed flora, fauna and wildlife through mismangement allowing unacceptable fire risks to lead to wild fires (f) caused environmental harm by decreasing slope stability, increasing soil erosion and depleting tree cover.

Image by Eric Von Dutch: place-holder pending approval.


Ka ora te Whenua, ka ora te tangata.

“Tiwaiwaka is a collective of people committed to healing the mauri of the whenua.

We bring together our gifts and abilities, matauranga, skills and experience, and networks throughout Aotearoa, many groups and individuals, all committed to realising this vision, each in our own way, regardless of culture, religion, beliefs, history, etc.

It works by sharing this vision and empowering more and people to give it effect. We share a common voice that in time will embrace the whole of Aotearoa.

By following the Principles of Tiwaiwaka we have a way forwards that gives us hope for the future.”

Download, at no cost, Robert (Pa) McGowan’s short but inspiring guide to the way forward: Tiwaiwaka.

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