About the Reserve Management Committee
We meet on the last Tuesday of even-numbered months at 7.30pm at Stoddart’s Cottage.
Purpose of this Blog
To create a forum to exchange ideas of how to use the wilder areas of our reserves returned to the unique native forest that once covered our peninsula.
Not all traditions are good traditions. In the Diamond Harbour area we have the not so great tradition of dumping garden waste in our reserves. It may not seem a problem to drop “biodegradable waste” off in an area where it will eventually rot down… but it is.
Diamond Harbour has a big pest plant problem: banana passionfruit, climbing asparagus, prickly pear, elephant’s ear succulent and more. These are pest plants because they compete with or outgrow native plants so an ecologically diverse area can instead become dominated by the pest plant. Why do we have these pest plants in our reserves? Because they are escapees from people’s gardens – either due to birds dispersing their seeds or because people have dumped their garden offcuts into reserves where they have re-established themselves. If we don’t keep on top of this problem we may just end up with pest plants in our reserves.
As part of the Christchurch City district we are lucky to be one of only a few areas around the country which is provided with a free green waste bin. Use it! Offcuts from garden plants can go in your green bin and be collected weekly (apart from cabbage tree and flax tree leaves which can damage the industrial composter). If you have too much garden waste for your green bin, local business Treekind offer an on-the-spot mulching service.
It is an offence under the Reserves Act 1977 to dump any kind of plant in a reserve. Claire Le Grice, principal advisor of regulatory compliance at Christchurch City Council, notes, “If an individual deposits garden waste in a public place then they may also be committing an infringement offence under the Litter Act 1975 and this conduct may result the issue of a fine”.
Native plant nursery at DH School
It’s an exciting time for the native restoration of our reserves. We have local people planting, weeding, trapping and advocating, all on behalf of our indigenous flora and fauna. Massive gains have been made in recent years in the areas that have received the care of volunteers. With the growing momentum comes a growing demand for native seedlings to displace the weeds and provide the seeds for the next generation of forest.
To meet this demand, members of the Diamond Harbour Reserves Management Committee have teamed up with the school to build a nursery for native plants on the school garden site. We are close to completing shade houses that will produce up to 2000 plants per year sourced from remnants of the original local forest cover.
We hope that the school pupils will be able to carry out an active role in all stages of propagation, seed collection and sowing, pricking out, cuttings care, potting up, watering and weeding. Besides teaching children the nuts and bolts of plant propagation, there are two major educational goals:
1) Developing an understanding of the unique Banks Peninsula indigenous ecosystems.
2) Encouraging an appreciation of the multiple benefits of reforestation: habitat for birds, reptiles and insects, erosion control, improved water quality, weed suppression and carbon sequestration.
We will be looking for more volunteers to help with the nursery tasks, both with the school pupils and just to get the job done when the kids are not available.
But one thing we don’t need is any donations of plants. Any seedlings originally sourced from garden centre plantings are often North Island plants, and genetically not appropriate for this area. Great care will be taken to ensure that all plants produced are sourced from the tiny pockets of remnant local coastal forest that survived the great human land clearance.
This may seem overly pedantic, but when we consider the bigger picture of how little genuine Banks Peninsula forest remains, the Diamond Harbour reserves could be a significant refuge for our unique ecosystem.
Understanding how biodiversity works in ecological systems is a subtle science. The resilience and strength of a system depends on having all the complexity and variation that nature has provided, not a simplified version that humans often prefer.
Renowned Banks Peninsula botanist Hugh Wilson was kind enough to review our vegetation management plans. He and the professional biodiversity rangers with whom we work, agree that the biggest threat to preserving our unique patch of biodiversity, is introducing the wrong plants which can often dominate in many ways.
Allowing introduced plants to grow and spread their seed in the reserves is an action that often cannot be undone. We are making the extra effort from the beginning to ensure that we are propagating our own local native forest.
We are very lucky to have an experienced nursery operator to oversee this operation. Andrea Hunt has recently moved into the area from Auckland, where she has been growing native plants for restoration since 2000. In recent years she has been managing volunteer restoration work in local reserves and two community native plant nurseries at Kaipatiki Project.
Andrea is keen to work with the school, to learn more about the special plants of Banks Peninsula. If you would like to help out with this exciting initiative in Diamond Harbour, please contact Andrea Hunt at firstname.lastname@example.org or 022 616 0631.
Green breaks, low flammability plants and reduced fire hazard
On Wednesday 17 May, at DH Fire Station, Dr Tim Curran of Lincoln University presented an informative talk based on his research, conducted both locally and in Australia, on which plants resist fire and those which burn readily.
This public talk was to help residents of our area to make informed decisions about how to make their properties as fire resistant as practicable.
The talk was well attended and Tim gave an entertaining and educational presentation covering his research, putting this into the context of New Zealand’s ecological history and the impact of global warming, which is predicted to increase the likelihood and frequency of forest fires in New Zealand in the future.
He covered the history, use and benefits of green fire breaks, i.e. using low flammability plants to slow down the spread of fires in forests, to reduce the risk of fires starting in high risk areas such as tracks, and to protect properties. He also explained how the layout of one’s garden and house surroundings can make one’s house more defensible to oncoming fires.
Everyone who attended went away with a raised awareness of the increasing risks we face and some knowledge of how to mitigate them.
For those who were unable to attend, and indeed those that did, Tim has provided a list of useful websites:
Several of the slides from his presentation (including those showing the results of the analysis) are available online on the council website:
At the more general website here:
https://www.ccc.govt.nz/environment/fire/porthillsfire (in the section at the bottom: Resources)
Other resources include:
Fogarty LG (2001) A flammability guide for some common New Zealand native tree and shrub species. Forest Research Bulletin 143, Forest and Rural Fire Scientific and Technical Series Report 6. Forest Research Institute in association with the New Zealand Fire Service Commission and National Rural Fire Authority, Rotorua, Wellington.
Wyse SV, Perry GLW, O’Connell DM, Holland PS, Wright MJ, Hosted CL, Whitelock SL, Geary IJ, Maurin KJL, Curran TJ (2016) A quantitative assessment of shoot flammability for 60 tree and shrub species supports ranking based on expert opinion. International Journal of Wildland Fire 25: 466-477. http://www.publish.csiro.au/WF/WF15047 (free download)
Sam’s Gully – Have your say
Good fences make good neighbours, or so the saying goes. Nowhere are good fences more important than if the neighbours in question are sheep and native forest. Most of our indigenous species are prone to grazing, so reforestation efforts are futile until we know that stock will be permanently excluded.
That’s why for more than a decade, locals have been requesting that Sam’s Gully between Marine Drive and Bay View Road be fenced. Last month, quite out of the blue, the council announced that it was to finally happen. A week later we had a fence. A day after that Diamond Harbour School pupils were planting fire resistant native trees alongside the school track.
The fence has not changed the tenure of the land. It is still part of a larger block that is zoned residential and spans from Hunters Road to Waipapa Ave. For the foreseeable future, pasture within this block will continue to be leased for grazing, with the possibility that at some stage it will become housing.
Sam’s Gully, like Morgan’s Gully is not economic for either farming or housing. Its steep sides are prone to erosion with many under-runners pumping silt into the stream below and eventually into our harbour. It is full of the worst kind of weeds for pasture, but surprising few for native forest restoration. The long grass and gorse create a fire hazard that threatens all adjacent properties. For these reasons, it’s difficult to see any constructive use of the land other than regeneration into indigenous forest with passive recreation like walking tracks. Restoring the land to its original plant communities will fix all the problems listed above, while locking up tons of carbon and turning waste land into a valued ecosystem.
Unfortunately, due to somewhat complex council policy, neither Sam’s or Morgan’s Gully between Bay View Rd and Marine Drive can be officially classified as a reserve at this time. However, the Reserves Management Committee understands that it is very unlikely that the gullies will ever be anything else, so from a pragmatic point of view we aim to treat these areas as if they were part of the existing Diamond Harbour reserve network.
It is proposed to manage the vegetation in Sam’s Gully to eventually return it to its original indigenous plant cover. The process will involve planting around 5000 native plants that are sourced from original forest remnants within the Mt Herbert Ecological area. At the same time, invasive weeds would be controlled. A walking track will be developed to link Marine Drive with Bayview Rd.
Plantings will initially consist of around 50 different species that will spread their seeds into the gorse and broom and eventually replace it. Taking a long-term view, it doesn’t matter exactly where in the gully these initial plants are put as 30 years from now, their seeds will spread everywhere. However, in the medium term big gains can be made by targeting the planting around boundaries, tracks and areas of high erosion.
As the land is in a planning limbo, we are seeking a mandate from the wider community to proceed with the plan outlined above. Please send any comments or suggestions to the Reserves Management Committee email@example.com.
Coastal tracks to get upgraded
The walking tracks through our little village will one day form part of something much bigger. An ambitious project to create a walkway between Godley head and Adderley Head has been underway for some time. The Head to Head Walkway plans to follow the coastline as much as is practicable linking existing tracks in stages to eventually create a multi-day walk right around Whakaraupo.
It’s early days for the project, but one thing is clear, the existing cliff track from Charteris Bay to Purau is ideally suited to be part of the finished Head to Head walkway. This means that money is available to up-grade this section of track.
The Reserves Management Committee is often asked if we can do something about the rough condition of this track. It seems that there are many people in our community who would like to walk along the Coastal Cliff Reserves, but find many parts of the track too hard to negotiate. There are others, who like it just how it is and see that we will lose something if it’s all up graded to a gravelled footpath.
The proposal outlined by the council will be a sensible compromise between these 2 positions. They certainly don’t intend to turn the track into a sealed footpath, but will address some problem areas to make it safer and more accessible. Specifically:
Remediate any areas of risk to public safety, including rockfall, unstable trees, difficult sections where there is the potential to fall etc.
Upgrade sections which people with limited joint movement find difficult to negotiate. These will be a few areas with large steps or boulders.
Address any areas where the track is causing unacceptable erosion.
Try to avoid wooden steps and structures.
As far as possible, achieve these goals by re-aligning or shifting stones rather than building bridges or steps.
This means that the track will remain mostly the way it is. There is no intention to upgrade the entire surface to gravel; although specific high use sections could be gravelled as needed.
People who walk these tracks would have noticed the new signage installed over the past 6 months consistent with other parts of the Head to Head walkway. The actual track work should start quite soon and the first stage is an assessment of what needs to be changed and what should be left as it is. This is the chance for anyone to let us know their opinions. As always, the Reserves Management Committee is keen to hear from anyone who has specific concerns so we can pass these on in the planning stage and create a walkway that serves the needs of our local people.
Please send any feedback to the Reserve Management Committee at firstname.lastname@example.org.
Would you believe that Ngaio is in danger of extinction in Diamond Harbour? Yes that’s right Ngaio- Myoporum laetum. The native tree that’s everywhere. It grows like a weed, spreads like a weed and in fact, in the wrong place, it is a weed.
But in our coastal reserves it’s a highly valued tree. It’s 100% indigenous and part of the unique feel of our forest. Ngaio has been gracing Lyttelton Harbour for over 20 thousand years. It’s incredibly fast growing, tolerates our dry climate and pops up in every corner of Diamond Harbour… and did I mention it’s also locally in danger of extinction? In fact, 50 years from now, if nothing is done, there will probably be no ngaio trees left.
So how can our most ubiquitous native possibly be that threatened? The answer is through hybridisation. People have introduced a related shrub from southern Australia called boobialla (Myoporum aff insulare). It’s also known misleadingly as Tasmanian ngaio even though it’s neither Tasmanian or ngaio. Boobialla is well established in our town and for many years it’s been mixing with ngaio to produce hybrids- plants that are a blend of the 2 species. With each generation, the chances of 2 pure ngaios breeding declines and reaches zero relatively quickly. At this point the next generation will not be boobialla or ngaio just hybrids
Boobialla seems to spread and grow even faster in our dry coastal environment than our native ngaio. That means that over time boobialla genes will dominate the hybrid population. As I mentioned, boobialla is more of a shrub than a tree, so the days of the spreading ngaio with its gnarled and twisted trunk will be gone. It will be just as extinct as if we cut the last one down for timber. Unfortunately, the hybrids will still be popping up in places where they’re unwanted – probably even more vigorously.
Boobialla is most common around the suburbs and built up areas where it was originally planted. So even if there’s a pure breeding Ngaio in your back yard, chances are that the flowers from it have been pollinised by a boobialla and the seeds will grow into hybrids. Away from the houses pure breeding ngaio still dominate, but over the last few years I’ve noticed more and more hybrids popping up even in the remotest corners.
To make matters worse, unknown volunteers have been planting boobialla or hybrids in our reserves particularly around the
western end of the cliff track. These were probably self-seeded trees that popped up in their backyards and they mistook them for native ngaio. So not only do we need to remove boobialla where we find it, we also must be very careful where we source the ngaio trees we plant.
While mature plants are very different (it’s easy to tell a shrub from a tree), young seedlings have more subtle differences. The most obvious is ngaio’s sticky dark brown-almost black growing shoots. Boobialla has green growing shoots no different in colour or stickiness from the mature leaves. Other differences are:
Ngaio has large leaves with obvious spots – Boobialla has smaller leaves with subtle spots
Ngaio grows into a rough barked tree – Boobialla grows into a multibranched shrub with smooth bark
Ngaio has large flowers: 10-15mm – Boobialla flowers are smaller: 7-8mm
Of course, the hybrids have a mixture of these attributes and can be very hard to pick until they are large and producing berries.
Boobialla and its hybrids are listed on the national pest plant accord. That makes it illegal to propagate or spread them in any way. This reflects the very serious risk it poses to ngaio. If there’s a tree on your property that you always thought was a ngaio, but actually has some boobialla qualities, please do the right thing and remove it. After all, there really is no shortage of real ngaio yet – they grow like weeds.
Predator-Free Port Hills Comes to Diamond Harbour – Trappers Needed!
Last November the Summit Road Society launched ‘Predator-Free Port Hills’, concentrating on the urban fringes between Halswell and Taylors Mistake, and on the harbour side from Lyttelton to Governors Bay. It has now arrived on our side of the Harbour.
In an ambitious bid to save our native fauna, our birds and lizards the scheme concentrates on residential areas for a number of reasons.
Firstly, because of residents’ plantings, the hill suburbs have some of our richest bio-diversity values.
Secondly, the concentration of dwellings means it can be a less time consuming approach to pest-trapping if households manage one trap each, rather than having a few volunteers looking after trap lines that cover vast tracts of land.
Thirdly, the peri-urban fringe we live in is not covered by other programmes. The Banks Peninsula Conservation Trust has announced a similar aspiration in its hills to our south. We don’t want our suburbs to breed predators who would re-infest areas that might be free of them. This is a way we locals can do our bit in the campaign to make NZ predator-free by 2050.
If you’d like to get involved, we can help out by advising on what type of trap might work for you or loaning you a trap from the Summit Road Society, and helping to set it up.
If you are already trapping we’d also like to hear from you so we can build a more complete knowledge of creature numbers, both the ones we want and the ones we don’t want. If in the longer term we are to succeed, we need this data.
Since the Summit Road Society announced the scheme in November a huge number of residents in the Port Hills and adjacent areas have started trapping.
If you’re interested and would like to borrow a trap, get advice on trapping or let us know about your current trapping activity please get in touch with your local coordinators:
Diamond Harbour/Purau: Adrian Heath 021 2066 452 or email@example.com
Church Bay/Charteris Bay: Sarah Pritchett 329 3344 or firstname.lastname@example.org
We also have a Facebook group – search for ‘Predator Free Port Hills – Diamond Harbour’.
Sarah Pritchett and Adrian Heath
The key to successfully growing new forests
Open land used to be are rare thing in Aotearoa. Before people arrived, the forest cover was almost
continuous at lower altitudes. Seeds of native trees would germinate in layers of thick composted leaves under the shade and shelter of the canopy above. The limited light would slow growth, but the seedlings were fully protected from frost, sun, wind and dry air. When a mature tree died, light reached the forest floor and the race was on amongst the established seedlings to be the next tree to fill the gap.
Understanding this is the key to successfully growing new forests. A lot of the trees we want to establish in our reserves are ill equipped to be in the open when young. Until they reach 1m high, they struggle to survive in direct sun or exposure to wind and frost. Open ground also resists colonisation as ungrazed grassland quickly develops a thick sward that prevents germination of almost all native seeds.
Around 700 trees were planted in open areas of Morgan’s Gully last year. Hardy types were chosen and they were watered at great effort throughout summer. There were some casualties and very little growth as the trees entered survival mode. They now need to be released from the smothering grass and hopefully after another burst of spring growth they will be able to survive on their own.
Another 500 or so trees were planted under the shelter of gorse. It’s no surprise that these trees have fared significantly better even without watering, but they still took lots of hard work. Unpleasant gorse cutting and maintenance is a similar amount of work to the watering, releasing and replanting of causalities needed in the open.
There are however some much easier options. 500 plants went in under willows in the upper gully. While the open plantings struggled just to survive, the willow plantings almost doubled in size. The willows can be removed once the natives are well established and any damage done will quickly be restored.
But the biggest bang for buck in last winter’s planting are the 400 trees that were planted under broom. I’ve only found 1 plant that hasn’t survived; most have grown over summer and none have been watered. There is no need to release them from grass as the broom’s shade has destroyed the sward. No tracks were cut, we just pushed our way in to plant. Best of all, nothing further needs to be done, broom only grows to 3m high and will not tolerate shade, so when the natives push their way to the light, the broom will be permanently replaced.
There is a native option for providing a nursery for young natives. Poroporo grows rapidly in the open and provides great shelter. It’s also fire resistant and produces fruit that attracts the birds. I’ve seen plenty of self-seeded natives growing under poroporo in Purau reserve, particularly when the native herb haloragis is growing as well.
Most of us in Diamond Harbour are probably sick of constantly pulling poroporo out of our gardens, but a weed is just a plant in the wrong place and poroporo is in the right place when it’s part of the natural succession on our reserves. Likewise, it’s taken me quite a bit of time to overcome my prejudice against broom and gorse. I used to work on farms where thousands of dollars were spent annually preventing these terrible weeds from destroying pasture. But on land set aside for native reforestation, rye grass is the enemy and rapidly growing, shade-intolerant woody shrubs are our friends.
Native Habitats that will protect us from fire
What would happen if the reserves around Diamond Harbour caught fire? It’s a question that has been on everyone’s mind recently. We all watched in horror as the Port Hills burned and we were presented with the cold hard reality that living in a semi rural environment goes hand in hand with the very real risk of wild fire.
Our reserves are steep, covered with vegetation (fuel) and tend to have houses directly above them. There is also limited access for fire fighters and potential ignition source from walkers on the tracks. Your Reserve Management Committee takes this hazard seriously and has already been working on mitigation measures that are practical and timely.
We are fortunate to have a pool of quality research to guide us in making our reserves as fire safe as possible. On the practical front, Liam Fogarty from the New Zealand Fire Service Commission asked hundreds of rural fire fighters which type of plants burnt and which ones resisted. The resulting data built up from real fire fighting experience from all over the country indicate some wild vegetation covers to be much safer than others.
Dr Tim Curran from Lincoln University is taking a different approach; he is systematically measuring the flammability of various New Zealand plants in laboratory conditions. The results are consistent with Fogarty’s findings giving us a great deal of confidence that we can significantly reduce the fire risk by changing the types of plants on our reserves. Dr Curran very kindly visited Diamond Harbour last year. He spent a few hours looking around our plantings and giving us excellent advice that has certainly changed the type of plants that I have been propagating.
It’s probably no surprise that the most flammable vegetation by far is long dry grass, closely followed by gorse. Rest assured that it will be a major priority of the RMC to replace these plants as soon as possible starting with areas that pose the highest risk to property.
Almost all exotic plants that dominate our reserves pose a real risk: pine, eucalyptus, pride of madeira and others are nothing more than dry kindling waiting for a flame. One exception is broom which is quite fire resistant, so we should avoid clearing existing broom as this will inevitably lead to long grass in the short term and possibly gorse in the medium term. Broom is an ideal habitat to protect native seedlings and will be killed by the shade of the trees as the native forest develops.
The best news from the research is that native NZ plants are among the most fire resistant in the world. Our native forests also become less flammable as they mature. So doing nothing else but replacing the exotic plants on our reserves with natives will significantly and permanently improve the fire safety. With sensible choice of species our reserves become “Green Fire Breaks” – habitats that protect property.
Some of the least flammable plants include many natives that have been extensively planted already. Five finger, fusia, coprosmas, lancewood, kapuka, poroporo and putaputaweta are practically unburnable. Mahoe, ngaio, ribbonwood, makomako, koromiko and tarata are also very resistant. The faster that we can get these species to dominate our reserves the better. A small number of native species need to be avoided or used with caution so we will be seeking expert advice to ensure that they don’t pose a risk to our community.
The Port Hills fire is a wake up call that we can’t ignore. I am sure that future fire safety of reserves will be a top priority for council staff and I expect they will provide invaluable advice over our next planting season. Now more than ever we need to ensure that the right plants are planted in the right areas. If you would like to be involved in the process of transforming our reserves into an indigenous and fire safe environment, please contact the Reserve Management Committee.
Saving Purau Bay Reserve
There are plenty of weeds that have an impact on Diamond Harbour’s native habitats, but the ubiquitous Banana Passionfruit is by far the most devastating.
The reserve area that borders the western side of Purau Bay used to be the most heavily infested area. I would take school groups to the beach down a makeshift track along the dry stream bed draining Rawhiti Tce. We called it passionfruit gully. The kids would return to camp with bags full of delicious yellow fruit and several times a year I would hack away the vines to keep the access open.
Over a few years I noticed large native trees succumbing to the thick smothering vines. Mahoe, ngaio and red matipo more than 20 years old would die once their leaves no longer received sunlight. The area seemed destined to become nothing but a blanket of weeds. But I also noticed that the trees benefited from my track cutting efforts. I was encouraged by one kohuhu in particular which had a spectacular burst of spring growth after most of the vines on it were severed. I started putting in a few hours more work to keep a few more of the older trees alive by cutting vines further back from the track. I was amazed by how just a little weeding tipped the balance and allowed the natives to win.
A quick survey of the reserve revealed that banana passionfruit covered about 65% of land area and increasing. Less than 20% of the sunlight was being utilised by native plants. Unfortunately, the seeds produced by this resource did very poorly. They competed with millions of passionfruit seeds for dispersal by the birds and those that were dispersed had very little chance of landing in a suitable habitat to grow.
That was 10 years ago. Over that time, I’ve been working with the council to turn the tables on the weeds and I’m happy to report that the natives are now well and truly winning.
Only a handful of passionfruit remain in the cliff track control area between the Scout den and the wooden steps. Now a survey shows about 70% native cover, but more important is the trend. Walk the track in late summer or autumn and the trees are thick with native berries. Birds are everywhere, spreading those seeds to every square metre of reserve. The areas that are not actually under native forest are the perfect habitat for these seeds to germinate and prosper. Crawl under the broom and you will see native seedlings enjoying the shade, shelter and nitrogen that this excellent nursery species provides.
that goes by involves less and less weeding work as the source of seeds declines. But weeds don’t respect property boundaries and seeds relentlessly spread from anywhere that birds can eat the fruit. That’s where everyone can help. Banana passionfruit is very easy to kill. Just gently tug on a vine to follow it down to its roots. Small to medium vines are surprisingly easy to uproot. They won’t regrow from small root fragments or above ground material. Larger vines can be grubbed out or cut and pasted with herbicide.
Other areas of reserve are now being rid of this terrible pest by a team of volunteers. It’s time to eliminate the seed source throughout our community. If you have this plant on your land or road frontage, please remove it. If you walk our reserve tracks regularly, take a little time out each walk to up-root a vine or two. Banana passionfruit is recognised worldwide as a threat to biodiversity. Without it our native forest has a great chance of thriving – definitely worth sacrificing a few bags of free fruit for.
This year volunteers planted over 2,000 trees and shrubs in Morgan’s Gully. This fantastic effort showed the broad and passionate support that our community has for establishing native forests in our reserves. It represents over $7,000 dollars in direct costs and many hundreds of hours of volunteer work, but there’s still lots of work ahead. If we get a typically dry summer, many of these trees will need to be watered and released from weeds just to keep them alive. It will be around 3-10 years until we see the forest canopy close over and smother the gorse and the hundred or so volunteers who helped out can look at a new forest with satisfaction.
So how much forest do we gain from all this effort? Around 5,000 square metres (half a hectare). Considering we have 30-60ha of reserve land suitable for regeneration into natives, this could be quite a depressing figure. Luckily we can count far more than just the area of forest planted. A few years from now these plantings will start producing seeds. We can expect wind and birds to distribute the offspring of these 2,000 hard won natives to every square metre of Morgan’s Gully. The vast majority will die, but what does that matter when the seeds number in the millions? One in a thousand survivors will be enough to ensure exponential growth and the eventual natural reforestation of the whole gully.
So that’s how we should look at our planting efforts, we are not gardeners planting out an area to reforest. We are in fact seed farmers hand picking the best, most productive land to grow the types of plants that produce abundant seed. If we ensure that there is plenty of mahoe, five finger, kapuka and red matipo in the plantings there will be copious amount of bird dispersed seed. They like no better place to germinate and grow than under a canopy of gorse and they will push through to make a forest without us needing to do a thing.
I have seen this process first hand in the hills around Tawa where I grew up. As a boy, I watched the marginal farmland that surrounded our valley turn to dense gorse. Locals would moan and say that someone should stop the onslaught, but luckily it was uneconomic to do anything but abandon the land. Now, 35 years later, the dispersal of seeds from tiny pockets of neighbouring bush has worked its magic and transformed the land to a native forest. Earlier this year, I walked through this forest in awe. It was hard to reconcile the environment I was in to my boyhood memories. In places the odd surviving gorse plant was pushing its way 5m to the light, but it was obvious it was doomed. Everywhere there were rotting gorse stumps, killed by the shade of the trees above.
Unfortunately, this process is not inevitable in Diamond Harbour. Unlike 1980s Tawa, there is one major barrier that we have to overcome. It’s not just native seeds that are dispersed into the reserves, but also millions of exotic seeds. A few types of plants are capable of out-competing the natives and producing their own exponential spread. These are the environmental weeds, the plants that can’t co-exist with a native forest.
So the mantra of reforestation is to “change the rain of seeds”. We need to boost the desirable seeds and eliminate the undesirable. In most places the native seed source is already in place, so by far the most effective action is to destroy the weeds.
What is a Native Plant?
What a unique community we live in. Diamond Harbour is not quite like any other in the area. We feel an affinity with Lyttelton, but we have chosen a different environment to live in than those who spend their winters in the shade. We’re kind of like Akaroa, but subtly different. And I’m sure everyone would agree that we are quite distinct from Auckland- and like it that way.
There is a parallel between our unique identity as a community and our own indigenous plant communities. The types of plants that are native to Diamond Harbour are slightly different to Lyttelton and Akaroa. They are very distinct from the native plants found in the Auckland area, so much so, that the forest of the Waitakere ranges has a noticeably different feel and aesthetic to our native bush.
What plants are native to the area we live in? Here’s a list…
Yikes! That’s 548 species of plant and even if I knew those scientific names, most of them are tiny obscure herbs that I have never heard of. Luckily, we can leave that list for the dedicated botanists. DoC has prepared this shorter list of the 140 most commonly planted and recognised species- with common names included.
The local flora is as much defined by what is missing as it is by what is there. Every area of this country has a unique native biota. This is what makes for the true biodiversity of Aotearoa. Unique and diverse flora leads to unique and diverse habitats for fauna and a unique and diverse “feel” to the landscape for us humans. This has always been recognised by biologists, but was first formalised by John Nicholls in the 1970s. He devised a scheme to divide New Zealand into areas in which “the topographical, geological, climatic, soil and biological features, including the broad cultural pattern, produce a characteristic landscape and range of biological communities” Today this idea has given us 268 ecological districts each with its own list of native plants, insects, birds, fish and fungi.
Diamond Harbour is in the Mt Herbert ecological district (see map). This is the first point of call for deciding which plants are suitable for our reserves. The reserve management committee will aim to reforest the areas set aside for native plantings with plants native to and collected from the Mt Herbert ecological district.
The concept of a “New Zealand native plant” is therefore, both simplistic and unfortunate. For example, the pōhutukawa tree growing outside the Memorial Hall is no more native than the gum trees beside it. Don’t get me wrong: it’s a beautiful tree, it has spectacular flowers every December, it’s part of our local heritage, it brings feelings of nostalgia and memories of beach holidays, it’s doing no harm and plenty of good, it is valued and it should stay growing exactly where it is. But its roots are in soil that is over 700km south of its natural range. The fact that it is growing in Lyttelton Harbour not Waitemata Harbour means that it is an exotic tree. I’m glad we have areas of our community set aside for beautiful exotic plants like pōhutukawa, but It’s important to also set aside some areas for our own native forest. In such areas pōhutukawa and other North Island invaders are not wanted.
There are plenty of other North Island plants growing around Diamond Harbour. Like the pōhutukawa, most do no harm. But there’s no reason for any of them to be incorporated into our native forests, after all we have 548 certified natives to choose from instead.
Next month: Reforestation 101 or ”Change the rain of seeds”
The landscape we see around us is unrecognisable from how Banks Peninsula has been for the vast majority of its existence. In a geological blink of an eye, humans have removed 100,000 ha of native forest leaving less than 1% of the original forest cover that dominated our home for 20 million years. Erosion has filled our harbour with sludge that used to be soil bound to the hills by the roots of giant podocarps. Exotic plants were brought from outside areas and now cover 95% of the land area.
Diamond Harbour has no old growth forest. The small patches of bush we see today are part of the 4% of Banks Peninsula that has regenerated from cleared farmland over the last 50 years or so. Even what appears to be native bush is usually a mix of native trees spread from neighbouring bush remnants and exotic plants from gardens and naturalised weeds.
The good news is that we have some areas that have been set aside to return to the original forest cover. Mainly the areas of reserve through which the cliff track and coastal routes run. A Stoddart Point management plan objective is “To manage vegetation in such a way over time, to establish the original indigenous plant communities of the area, and to enhance the habitat for its indigenous fauna, while not compromising the stability of the ground.”
Thus over a few generations this relatively small area of land could become a “museum piece”- a tiny part of Banks Peninsula that represents what we have lost. Somewhere that our descendants can experience what it would have been like 1000 years ago to walk through forest that was unique to just here, like no other forest in the world.
The forest that once dominated Lyttelton Harbour was remarkably different to the rest of New Zealand and subtly different to the rest of Banks Peninsula. It tells the story of Banks Peninsula’s isolation as an island for the first 20 million years. The distribution of species such as beech, which have no seed dispersal, tells the history of glaciation where quite literally, the spread of Red beech is slower than a glacial pace. Some species such as Hebe strictissima are endemic to Banks Peninsula and found nowhere else in the world.
Everyone, myself included, has exotic plants that they like. Fruit trees, veges and the good old back yard lawn all have their place; as do decorative plants from oak trees to rose bushes. It’s clear from the fact that 95% of Lyttelton Harbour basin is under some form of introduced vegetation, that hundreds of types of exotic plants are valued by our community. But just as it would be inappropriate to try and plant natives in the middle of the rugby grounds, the tiny areas we now have set aside for native forest should be managed to eventually have only Lyttelton Harbour natives. If we don’t make an effort to grow our own unique native forest in our reserves no one else will and the Lyttelton Harbour forest will be lost forever.
One thing is for sure, there are a significant number of local people who would like to see as much of it as possible return to its former glory.