Gahnia Grove - Site summary and discussion's News

May 06, 2019

Report for April 2019

Liaison CommLis* Monitoring Sitework**
April 0 0 23.5 20.5 April total: 44
YTD 80.75 1.75 225.75 298.25 YTD Total: 606.5

* ad hoc Community Liaison eg interested Reserve users
** includes Weed control, mulching for moisture retention, onsite assessment and planning

Effectiveness of weed control to date,combined with current continued drought only slightly relieved by recent showers and brief rains, means it is too early to do the next stage, which will be significant kikuyu pullback once the ground is wet enough to rot the pile, and further culling of exotic herbs, by uprooting where there are no wanted seedlings to be disturbed, and by cutting or snapping of stems where the soil is to remain undisturbed to protect existing seedlings.

We wonder how many seeds are poised to germinate when the soil is wetter, and how many of them would survive uprooting of adjacent exotics. If we see a convenient opportunity we will cull exotics by the two different means - cutting or uprooting - and compare results in similar conditions. Since we do not know how many seeds are where, the results may not be informative, but may suggest a desired course of action for next time.

Among the exotic herbs, culling will target all the Black nightshades, since we now have at least half a dozen native nightshade specimens which, thanks to iNaturalist, we have learned to recognise and can now retain indefinitely. Though the black nightshade have provided very valuable shade and shelter through the autumn, it would be preferable to have a native species doing the job. So we will try to minimise germination of the plentiful seed crop of the black nightshades ( by composting in a pile where seedlings can be easily pulled) and broadcast the seeds of the native nightshades once they are ripe.

Updates and discussion posted during April can be seen in Gahnia Grove's "Journal", see link at top of this page or

Posted on May 06, 2019 01:29 by kaipatiki_naturewatch kaipatiki_naturewatch | 0 comments | Leave a comment

April 16, 2019

Possible "lost knowledge" re wattles...?

20 years ago it was common practice to ringbark or fell black wattles (Acacia mearnsii) and brush wattles (Paraserianthes lophantha ) without further intervention, as they do not regrow. Personally, I cut down a number of juveniles and did not see any regrowth while working on the site for a couple more years, while on the same site , dozens of dead ringvarked wattles were felled for safety reasons due to creation of a new bush walk through their midst. Others had already fallen and lay rotting on the ground, making marvellous habitat.

So we were surprised to learn recently that contractors are often obliged to the use herbicide, in the belief that felled or ringbarked trees may regrow.

There may have been cases of regrowth of which we are unaware, so we have asked everyone we meet in the field for the latest info on this.

So far we have not heard of any experience of regrowth, and herbicide use seems to be common.

We look forward to learning of differing experience in the control of wattles, and in the meantime offer this example of a brush wattle felled without herbicide or further intervention and monitored till the beginnings of decay, in a monitored trial of chemical-free weed control conducted in collaboration with Wildlands Consultants:

Posted on April 16, 2019 06:52 by kaipatiki_naturewatch kaipatiki_naturewatch | 0 comments | Leave a comment

April 15, 2019

New weed invasions in March

- A single seedling Sun spurge on CHF bank - uprooted easily

- Two Swan plant seedlings, one in the ex-kikuyu top of the Arena, and one on CHF bank - both uprooted

Posted on April 15, 2019 23:39 by kaipatiki_naturewatch kaipatiki_naturewatch | 0 comments | Leave a comment

New native finds in March

Blechnum parriseae (the former "Doodia media") - a single small plant c.20cmH under harakeke leaves on CHF bank - released from weeds, expected to multiply

Kawakawa seedlings in the canopy margin on lower CHF Bank

Posted on April 15, 2019 23:36 by kaipatiki_naturewatch kaipatiki_naturewatch | 0 comments | Leave a comment

April 14, 2019

A native arrival in the kikuyu margin!

A small spread of Hairy pennywort, endemic to NZ, was found in the edge of the previously sprayed-kikuyu margin at the top of CHF bank. There is probably more hidden under the kikuyu, to be explored later.

Part of the plant was dug up from loamy soil with a stick and transplanted to a more secure location under the first harakeke herbicide-sprayed kikuyu margin of the Arena, where it is hoped it will spread further, contributing to ground cover. It's tiny red-tinged leaves cling close to the ground so it is unlikely to attract disturbance.

This specimen may not survive, as it was crudely uplifted from dense clay and planted without soil preparation. However, it is not uncommon locally, and we will be looking for more.

We have also collected from a neighbourhood berm a small portion of Nahui (Alternanthera nahui) and layered it in potting mix with hopes of producing specimens suitable for planting in the kikuyu margins. It is a very hardy and vigorous plant once established.

We are also looking for identifiable, ie flowering, Microlaena stipoides, which is still seen occasionally in streetside hedges, though less frequently than a few years ago, probably due to herbicide use and, it appears, replacement by the invasive and increasingly common Veldt grass, observed in the same habitat.

Posted on April 14, 2019 08:03 by kaipatiki_naturewatch kaipatiki_naturewatch | 1 comments | Leave a comment

Why we love weeds....

[Posted Spring 2018 in the Kikuyu Margin Project, now replaced by separate Projects for each section of Gahnia Grove's kikuyu margin.]

It's often hard to explain why we love weeds - while doing everything we can to get rid of the most threatening ones.

As the commonest, most rapidly produced plant material on a site, they are the first available source of Food for Plants - once rotted down, they form humus, nutritious and, more importantly, breaking up the clay to allow roots and water to penetrate. Without enough humus, plants suffer more from both drought and flooding, and can't absorb enough nutrients. The dense clay typical of Kaipatiki is rich in nutrients, but without organic material in the soil, plants can't absorb them.

The same goes for water. Rotted or dried plant material incorporated into the soil creates micro-channels for water, allowing it to reach plant roots - and reducing the amount that washes downhill, making paths slippery, causing erosion and polluting the streams and seas with sediment.

Diversification and protection of native vegetation are the planned outcome for these previously-sprayed and trimmed margins of the mown kikuyu lawns. The native trees likely to arise spontaneously on this ridge will be wind-hardy and acid-tolerant, and unless the soil is rehabilitated will need to be drought-tolerant if they are to survive.

Weed-suppression will be by manual selection, uprooting or spot-mulching depending on the nature of the weed and the availability of mulch.

Spot-mulching is usually easier and more effective than uprooting. It also improves soil moisture and health, shading the ground and creating the humus that feeds subsequent plants.

It is our intention to avoid the introduction of materials from other sites, for disease-control and cost-reduction.

Therefore we depend on the mulch available on site - preferably from close at hand. As long as weeds are being abundantly produced, we have an excellent source of mulch for weed-control, moisture-retention and plant food.

Generally the first source of plant material for the rehabilitation of the soil along the edge of mown kikuyu is the kikuyu itself, as it continues to spread from the mown area.

Grass-growing season is here, and it's time to define the area of unmown, untrimmed kikuyu that, through manual pull-back, will generate the essential mulch to control its own regrowth from its clone-patch, while rehabilitating the soil.

It will look different to the customary short-back-and-sides.

It will have height.

It will grow in diffferent directions - rumpled, backwards, and sideways - instead of to a neatly trimmed edge, or smoothly downhill into the native planting. More and more, it will be growing upside-down, showing only the browned undersides of long leafy stolons. These unruly clumps of wiry stolons probably won't die till winter, when, now rearranged to inhibit growth, they will rot in the cold wet weather...leaving a small amount of loose loamy topsoil for next year's seedlings.

It will, increasingly, hold familiar weeds of pasture - docks, initially, then sow-thistles, wild carrot, Parsley dropwort, Ox-tongues, Scarlet pimpernel, vetch, Cleavers, Red deadnettle, Common and Purple-top Vervains, Prunella, Lesser swinecress, chickweeds, the native (and locally wild) Esler's weed, the often-present but seldom recognised native Nahui and Microlaena stipoides, and...the as yet unknown, to be identified, selectively eradicated, reduced, suppressed or nurtured as required - till, among these ground-breakers, emerge the kanuka, manuka, karamu, totara, mingimingi, the unknown contents of the present seedbank, and the products of wind and birds.

So bring on the weedy growth of summer along Gahnia Grove's borders, watch it grow up and diversify and be pulled out and trampled and mulched, wonder and wait and look for surprises.

Posted on April 14, 2019 07:58 by kaipatiki_naturewatch kaipatiki_naturewatch | 1 comments | Leave a comment

Report for March 2019

Hours for March, and for Year to Date - (the Gahnia Grove year having begun 20 May 2018):

Liaison - 1 [YTD - 80.75]
Community Liaison (Reserve user asked where she could sign up to do same) - .25 [YTD - 1.75]
Monitoring/research (mainly Observations, uploads and discussion on iNaturalist) - 7.5 [YTD - 202.25]
Sitework (includes Weed control, "tiptoe" path creation for habitat protection, onsite assessment and planning, and maintenance of amenity through disposition of weed materials and mulch bordering mown kikuyu)- 21.5 [YTD - 277.75]
March total: 30.25
YTD Total: 562.5

Kikuyu control has gone extremely well, thanks to the cordon and the supportive and flawless collaboration of the Ventia Integrated Services team.

An early observation of the kikuyu margin, before wood chip mulch or cordon, has some info on the technique being used:

The initial approx 80m of kikuyu margin curving around the existing planting on the Glenfield Rd side of Gahnia Grove has been reduced to approx 40m by gradually eliminating the curves through pullback and wood mulch (releasing an increased area of kikuyu-eradication behind the cordon). This won't make much difference to mowers, but will substantially reduce the time needed for ongoing manual control along the mown edge.

Nine of the weed-control hours in March were spent on control of kikuyu in the margin.

Background to the Kikuyu Edge Control project is covered in a couple of earlier posts, here:

Observations of the Kikuyu Margin of each of the Gahnia Grove sub-sites can be viewed, with most recent at the top of the list and older ones by scrolling down, at these links:

CHF Bank Kikuyu Margin:

Arena Kikuyu margin:

Apron Kikuyu Margin:

Annexe Kikuyu Margin:

In addition, approx 50sq m of dense, thick mown kikuyu in the Arena has been removed by manual pullback - ie no cutting or breaking - since June 2018. We expect at least a few vertical rhizomes to have survived and to make their appearance with some new growth at the surface somewhere within the Arena , but these should be easily managed in due course.

The major March activity since recent rains, however, has been the delightful task of looking through and among the dense stands of 2mH wildflowers - not at noon on sunny days when competing with honeybees and bumble bees - finding a few native seedlings, removing most of the unwanted seedlings such as Paspalum, and thinning the wildflowers where there is sufficient shade without them, as the ground is still dry:

We have been very pleased with the results of trial control of several shrub weeds by mulching of live plant or stumps, rotting the roots at least partially until the plant can be easily uprooted.

Currently we are trialling the use of Tradescantia piles to hasten rotting and suppress regrowth in Japanese honeysuckle, Blackberry, Kahili Ginger, Alocasia brisbanensis (Elephant's Ear) Arum lily and Cape Honey Flower. Many plants have already been completely uprooted so far, especially those that had their own live foliage included in the mulch.

More updates on those trials later, but here are some notes regarding an earlier trial of Agapanthus control control:

Comments on brush wattle and Moth plant seedling removal:

Tradescantia control is now well underway with a defined boundary incorporating those piles being used as mulch. A detailed report on this will be provided next month.

Posted on April 14, 2019 05:58 by kaipatiki_naturewatch kaipatiki_naturewatch | 0 comments | Leave a comment

April 02, 2019

Agapanthus - trialling no-dig no-chemical eradication

The observations at the link below were made in the Arena, where about a dozen medium sized plants to c. 50cm H were first observed in June 2018.

They were controlled by pulling or cutting off some of the leaves as convenient, piling the leaves on the stems (insufficient mass to cover the tubers completely) and thereafter pulling on exposed tubers in passing , loosening or uprooting them when possible with minimal effort.
Surprisingly, many tubers were uprooted without effort by August 2018. Tubers continued to be piled over remaining tubers, both to assist rottjng and to ensure monitoring.

All except those rooted against tree trunks were removed in this way by January 2019.

Seedlings emerged abundant around the tubers in Spring, snd were controlled solely by squashjng or pulling off their tiny leaves, since they were too small to grasp and uproot from the dry clay soil.

Any remaining Agapanthus have been, or will be, observed and will, thanks to the iNaturalist Explore search, automatically be added to those currently appearing at the link above.

Posted on April 02, 2019 18:28 by kaipatiki_naturewatch kaipatiki_naturewatch | 0 comments | Leave a comment

March 17, 2019

Toxic saps, sharp sticks, wasps nests....

Having always been careful to avoid contact with moth plant sap, we recently experienced our first plant sap incident, with half-an-hour's partial blindness at home after accidentally snapping a Harakeke stem, causing a splash into one eye, and a smaller splash - with smaller effect - in the other eye.

Eye-wash with sterile saline helped soothed the discomfort, but it was an hour before both eyes could tolerate light.

Mentioning this incident in conversation, another volunteer reported having had a 3cm blister on his leg after walking through a Bayview reserve, off-track, in shorts.

Another volunteer was reportedly hospitalized after accidentally disturbing a wasps' nest in a Bayview Reserve.

And I learned that I am not alone in having had an eye injury from a stick. The mesh safety goggles are proving comfortable and effective, though they would not prevent dust or sap.

Posted on March 17, 2019 11:29 by kaipatiki_naturewatch kaipatiki_naturewatch | 0 comments | Leave a comment

Brush wattle and Moth plant seedlings removed in March

[NB this report was on March 18th. Hundreds more seedlings were removed in the last 2 weeks of March, and continue in April]

Probably 100-200 brush wattle seedlings, only 5-20cmH so could have waited, as they are a little hard to pull while the ground is so dry, but most observed have been quickly grabbed while cutting or uprooting dried oxtongue and wild carrot. The wattle seedlings are mostly in groups of 5-10, probably reflecting fallen pods.

We presume there are no birds that spread the seed, which is without fruit or other obvious attraction? And they are too heavy to spread on the wind, except perhaps in high winds while hanging on the tree. Do the pods open explosively, with enough force to move them far?

Moth plant seedlings are fewer in number this month, but some of those found, mostly among dense exotic herbs, have been up to 20cmH. One was c.1mH, on the margin of the Flame Tree Zone and under the karamu and ti kouka where a mature vine was found last year. This one, among a pile of cut Cape Honey Flower wood, may have broken and will need further removal when it regrows, the wood has been moved, and the ground is wetter. Most of the others seemed to be entirely uprooted.

Two Swan plant seedlings, and one on the kikuyu margin under the Flame Tree, were being observed as a novelty, and to perhaps determine which species they are, but after a recent news item about the toxic sap having caused 6 months' blindness in a Whangarei man, we decided to remove them now while they are small.

Posted on March 17, 2019 11:10 by kaipatiki_naturewatch kaipatiki_naturewatch | 0 comments | Leave a comment