Gahnia Grove - Site summary and discussion's News

August 15, 2019

Verbena incompta and V. linearis both removed from our list of "Benign exotic herbs" for Gahnia Grove

Both these species germinated with great abundance and density thorughout the bared clay banks, and grew to provide essential shade and shelter for these bared areas during Summer and Autumn. We expected to see them develop as tall single stemmed annuals, allowing other plants to grow beneath them as we recalled having in 1999 seen "Purple top", believed to be Verbena bonariensis, along Kaipatiki Roadside, where it was easy to knock down once mature.

Whether the incompta we have had identified here is the same species or not, in the conditions of a dry poor-soil ridge from which competing kikuyu and shrub weeds had been eradicated and native plants were not yet present, neither of these species showed any sign of yielding to old age by mid-August, and between the two of them they had achieved dominance over most of the area, with wild carrot and ox-tongue becoming scarce.

Both these Verbena species are know to be extremely tolerant of arid soils, and both developed many spreading stems from thick long woody roots at ground level.

So we decided it was time to remove them while they can still be composted usefully before Spring germination of both native plants and less-aggressive exotic herbs.

Few could be uprooted, and cutting stems low often leaves a large root mass on the surface, so we have broken most plants down over themselves, cutting the thickest (ie 8-10mm) stems as low as possible, and covered all roots and stem bases with their softer upper stems and foliage.

Hopefully most will weaken and be able to be uprooted. If not, this task will be ongoing for the coming year at least, unless enough mulch to suppress them can be produced from Spring growth of ox-tongue, wild carrot, Black nightshade and anything else leafy.

In either case, we expect to have to mulch a lot of Verbena seedlings this year.

These plants were difficult to uproot even as small seedlings. So though their welcome growth provided quick low shade, moisture retention and, when rains came at last, erosion control, in the conditions this year at Gahnia Grove we might have better advanced benign plant cover and the transition to native vegetation by mulching over most of them as seedlings.

But it is impossible to be sure, as without their hardiness through summer, the drought might have had even more impact on the existing native vegetation and the growth of benign exotics.

Posted on August 15, 2019 07:42 by kaipatiki_naturewatch kaipatiki_naturewatch | 0 comments | Leave a comment

August 02, 2019

Manual control of Pampas in the forest margins

Thanks to @chrise (a co-author) for the link to this 1985 Forest Research Institute publication about pampas and toetoe:
https://cdm20044.contentdm.oclc.org/digital/collection/p20044coll6/id/155

It will be confusing for some newer naturalists to see toetoe referred to as Cortaderia though! I only discovered the new name, or classification, a year ago on joining iNat, and already I was momentarilly perturbed to see the name "Cortaderia" applied to a native!

Having no formal education in ecology, I was most interested to see pampas described as a forest weed, as I have been removing small plants from this margin of dry kauri ridge regen forest underpines, tanekaha and other podocarps and understorey.

Not surprisingly, the clumps were larger and more numerous in the outer margin of solely manuka. I had been wondering, for a year, if this is an infestation on the way out as shade increases, or a growing invasion. I assumed it would get suppressed if dense shade increases fast enough, and removing or suppressing the pampas gives the forest time to develop the necessary dense shade. I have little experience of forest except urban Auckland.

Anyway, I am glad to confirm it has been easy to trample and later uproot all plants found under canopy whether inlight or heavy shade, and to suppress the large ones in the sunny margin by breaking down the culms and tall shoots and throwing the foliage over the clump, with a single summer follow-up intervention resulting of rotting of the whole plant gradually. I was told this is 1997 by a contractor. I can't remember if he used herbicide as well, but it doesn't seem to be necessary. Our single 6mH-3mW clump in full sun is now c.50cmH and mostly dead. It has live shoots remaining over about 1m x .5m, because we chose to allow growth to resume on one side, beside a public walkway, during the months of the summer drought.

I learnt from the pamphlet linked above that some native species have erect flowerheads, which is important as I had recently been told that erect flowerheads indicated pampas as a blanket rule.

Posted on August 02, 2019 21:29 by kaipatiki_naturewatch kaipatiki_naturewatch | 0 comments | Leave a comment

July 20, 2019

Report for end of Year One - June 2018- May 2019

May 2019:
Liaison: 1.5
Community liaison: 0
Monitoring & resch 13.75
Sitework* 22.5
YTD:
Liaison: 82.25
Community liaison: 1.75
Monitoring & resch 239.5
Sitework* 320.75
* (includes Weed control, fire hazard prevention, mulching for moisture retention, "tiptoe" path creation for habitat protection, onsite assessment and planning, and maintenance of amenity through disposition of weed materials and mulch bordering mown kikuyu)

Total May 2019: 37.75
Total YTD: 644.25

"Inch by inch, row by row...gonnna watch this forest grow" (Apologies to Pete Seeger)

Our plan a year ago was to attempt to release as many of the trees in this little piece of forest margin as we could from the currently most crippling honeysuckle invasion, and to turn back the kikuyu from the margin of existing native trees along the mown grass edge. To make the results sustainable and eliminate unproductive edging of two of the three existing parallel margins of mown grass currently invading existing tree margins, we hoped to gradually replace a large weed-filled area within these borders with wild native vegetation.

We expected this would take about three years, with approximately 10m of margin being freed from honeysuckle in the first year, with the 2 hours a week we were able to commit as a volunteer.

As in other restoration we have undertaken, we find the results exceeded expectations. The Project was so rewarding and interesting that we extended our initial honeysuckle control to 50m of forest margin, extending about 20m down the weed-filled bank and into the manuka/ckanuka canopy to eliminate all of the honeysuckle invasion from that area.

The "internal" previously mown kikuyu was most easily controlled during the year by a combination of "kikuyu pullback" and mulch, and the process led unexpectedly to its eradication from the entire area (of course with the expectation of ongoing incursion from the adjacent mown sward).

A number of weeds have been dealt with for the first time using our methodology, leading to many interesting questions and the discovery of some answers, including some improved efficiencies in management of vine and shrub weeds generally.

The visual results have proved pleasing to the public, many of whom now regularly express their appreciation, (and occasional ask for weed-control advice) despite no longer having access to an additional informal "path" of mown kikuyu surrounded by weeds, which had previously cut through the site connecting the roadside to the large grass recreational area. (The nearest alternate access from road to recreational grassed area is apparently also informal, much steeper, and the grass has worn away leaving it rutted, muddy and slippery in winter).

The pigtail cordon provided by the Community Ranger, with some hanging interpretive signage hand-made from recyclable plastic, has been effective thus far in protecting actual and potential revegetation from trampling and from conflicting weed management practices.

And despite the paucity of surviving trees along the outer margin, we are seeing a little wild revegetation already, though whether these seedlings will survive summer drought remains to be seen.

It is such a pleasant activity and place to be that we spent hours on site whether needed for weed control or not, always finding something to do whether or not it increased the efficiency of the Project.

We have now enlarged the area being thus treated and hope to formalise its boundaries with the Community Ranger, and with Kaipatiki Project who are engaged in restoration in nearby areas of this roadside forest margin, in order to achieve and document more labour-efficient results in the conversion of metres of weedy forest margin to numbers of native trees.

Here are some side-by-side views of change during Year One:
https://inaturalist.nz/posts/25965-side-by-side-site-monitoring-views-smvs-one-year-after-start-of-site-based-manual-restoration

KIKUYU CONTROL

The challenge we set ourself in Gahnia Grove in June 2018 was to test and demonstrate the efficiency of "manual pullback", a method we had developed based on observation of the behaviour of kikuyu in response to typical interventions in various conditions.

We had trialled "pullback with rotting" in 2001-03 in small areas of two different restoration sites, converting to native vegetation an area of mown or unmown kikuyu, including planted and wild native vegetation invaded by its uncontrolled spread. Manual pullback requires the kikuyu to remain uncut and unbroken, so that unrooted stolons pulled back on themselves suppress outward spread and rot their own live foliage and eventually the rooted stolons beneath. The rotting eventually progresses to deeper rhizomes, allowing them to be uprooted easily. The resulting mass of rotted grass and attached earth is then pulled backwards, extending the area of control and releasing immediately plantable or seedable ground with a relatively high humus content and earthworms supporting rapid growth of new vegetation.

In the observation linked below, a month after first manual intervention at Gahnia Grove, the previously herbicide-controlled lawn-edge under the harakeke at left remains free of any visible life.

Beyond this sprayed edge, an area of previously-mown kikuyu has been allowed to grow freely to enable manual control by "pullback".

A pile of drying honeysuckle placed on previously mown kikuyu defines the site boundary, incidentally partially-suppressing kikuyu at the same time:
https://inaturalist.nz/observations/13855288

Roughly the same view in April 2019 shows an area free of suppressive weeds, with released surviving karamu, wildflowers and mulched earth along the same border:
https://inaturalist.nz/observations/22398525

A recent post summarises kikuyu control in Gahnia Grove, beginning with a spontaneous intervention on 20th May 2018, followed up with an average of 6hrs a week onsite volunteer activity for 12 months, supported by the Kaipatiki Community Ranger and the year-long collaboration of Ventia's Integrated Services. Mowing of the recreational grass continued to maintain a smooth walkway and recreational area of bright green turf, while the suspension of line-trimming and herbicide-spraying allowed wildflowers to grow in its outer margin:

https://inaturalist.nz/posts/25613-kikuyu-control-june-2018-may-2019

The Annexe/Glade margin is also a mown-grass margin, but very different in composition, discussed here:
https://inaturalist.nz/posts/25758-the-annexe-and-glade-margins-of-manuka-canopy

BENIGN EXOTIC HERBS
- in the transition from aggressive weed invasion to wild diverse native vegetation

Since major removal of honeysuckle which had killed or imprisoned numerous trees, and other weeds eg 10mx10m of dense Cape Honey Flower and blackberry, Gahnia Grove has hosted benign exotic herbs throughout 50m of potential native forest margin, from the 15-20 year old manuka and older kanuka canopy up to the roadside kikuyu.

Benign exotic species occurring wild in Gahnia Grove during the year included 31 plant species, many of them hosting great numbers of honeybees. These species are listed here, using the generic iNaturalist.nz Taxon info and images:
https://inaturalist.nz/observations?place_id=any&subview=grid&verifiable=any&view=species&field:Benign%20exotic%20plants%20of%20Gahnia%20Grove=

Some observations of benign exotic herbs arising and retained in Gahnia Grove over the last year, ordered oldest-to-newest (This list is currently 3 pages of observations, and also may take a few seconds for photos to load as you scroll down):
https://inaturalist.nz/observations?order=asc&order_by=observed_on&place_id=any&subview=grid&verifiable=any&field:Benign%20exotic%20plants%20of%20Gahnia%20Grove=

It has been a joy to watch this dense but easily manageable wildflower bed providing diverse ground to prevent erosion while

- hosting wildlife:
https://inaturalist.nz/observations?order=asc&order_by=observed_on&place_id=130948,130991&project_id=wildlife-of-gahnia-grove&subview=grid

- creating mini-canopy to shade native seedlings

- retaining soil moisture - Through moisture retention, the benign exotic herbs are not only enabling native seeds to germinate and grow, but supporting the recovery and development of existing native trees in the margin of the forest canopy, including two juvenile putaputaweta and a pigeonwood; and the few karamu that survived the honeysuckle invasion)

- minimising invasion of suppressive herb and grass weeds - both of species pre-existing this Trial eg herbs and grasses (mainly Broad-leaved dock, Creeping buttercup and Paspalum sp and exotic umbrella sedges Cyperus eragrostis and congestus), and Tree/shrub weed seedlings (mainly Moth plant, Cape Honey Flower and Brush wattle)

- through soil penetration, moisture absorption and retention, and humus formation, enabling uprooting of new populations of aggressive weeds

An earlier post considers our planned use of benign exotic herbs in restoration:
https://inaturalist.nz/posts/25757-benign-exotic-herbs

while a more recent post celebrates the abundance of foliage-rich ground cover and mulch for seedling shelter, weed suppression and soil conditioning:
https://inaturalist.nz/posts/23376-why-we-love-weeds

WEEDS
"Watch it growing seed by seed, and protect it weed by weed......"

HONEYSUCKLE
The all-encompassing weed issue when the Gahnia Grove manual restoration trial project began in June 2018 was Japanese honeysuckle, which remains the greatest immediate threat from neighbouring forest margins.

We made some notes on Japanese honeysuckle control at Gahnia Grove here:
https://inaturalist.nz/projects/gahnia-grove-site-summary-and-discussion/journal/25759-japanese-honeysuckle-control-in-gahnia-grove-june-2018-19

Control of honeysuckle and blackberry, significant at the start of the Project, has required little effort or time since late summer. Control was thus able to be extended to the previously-unmanaged adjacent Flame Tree Bank, which we undertook with the more efficient and low-energy techniques that had been found successful and efficient in the Arena and Cape Honey Flower Banks - ie pulling in outlying runners, cutting vines from trees as high as possible, piling the vine over its roots, self-mulching for root- rotting.

The addition of any plant material available helped the rotting process immensely, loosening roots much sooner. Tradescantia, moisture-retentive and forming a dense mass when piled, is ideal for this purpose if it is already present and the mulch site is identifiable and accessible for ongoing control of the Tradescantia:

CAPE HONEY FLOWER

The second most significant weed on the site was Cape Honey Flower (CHF), summarised here:
https://inaturalist.nz/posts/26180-cape-honey-flower

MOTH PLANT

Several mature vines with pods were uprooted in June/July 2018 from two sites in Gahnia Grove. Uprooting was either entire or partial depending on soil conditions. Thousands of tiny Moth Plant seedlings in these two sites were uprooted in the following month or two, individually or the tiniest disturbed en masse then suppressed with mulch.

Dozens of these seedlings were incompletely uprooted, and along with one or two incompletely uprooted mature vines, emerged vigorously in Spring 2018. The repeat uprooting attempt at this time was often unsuccessful as the ground was dry at the time, but the broken stems resulted in prevention of further development of seedling or vines.

We will in future use mulch to suppress seedlings and loosen the soil, if wet ground is likely to allow successful uprooting before vines develop enough to affect nearby vegetation.

TREE PRIVET

Several specimens to c.4.5mH were beginning to suppress adjacent otherwise-thriving native trees on the grass margin, and were controlled by several techniques whose long-term results we wanted to monitor.

While initially 5 or 10 minutes was spent every few weeks on repeat suppression of the group of tree privets, by late autumn there was little regrowth on the second tallest, which had had its main branches all partially broken and bent down. The tallest, whose top was unable to be reached, had failed to significantly increase its height or to produce branches, but was still producing vigorous leafy shoots, and was felled at about 1mH in autumn. It has had leafy shoots picked off the remaining trunk tip occasionally since then.

OTHER WOODY SHRUB/TREE WEEDS
Chinese privet, Elaeagnus and Cotoneaster treated by the same basic method are all much diminished in size and producing only slow regrowth. A juvenile Elaeagnus and Tree privet in shade, both about 2mH before cutting or partial breakdown of main stems and branches, stopped producing shoots and were found to be easily uprooted.

The results so far are being collected here:
https://inaturalist.nz/posts/25777-woody-tree-shrub-weeds

TRADESCANTIA

Most of Gahnia Grove, below a road edge along a ridge, was without Tradescantia when first observed. There was a little under the honeysuckle-curtained canopy edge of the Arena, and a moderate coverage over the forest floor downhill, wherre it held many tuber ladder ferns, but both Tradescantia and tuber ladder fern tapered out within about 15m.

Cape Honey Flower Bank had a carpet of it along the canopy edge, thinner uphill perhaps because CHF obliterated light, and much thicker downhill into the canopy, where it deep and lush among the kanuka, mahoe and Flame Tree trunks. Like adjacent canopy, this Tradescantia-carpeted area held little understorey, but seedlings of pigeonwood, coprosma, and mahoe, as well as many juvenile and mature Elaeagnus, with Kahili ginger and Euonymus japonica.

Throughout Flame Tree Bank, and the kanuka/Flame Tree canopy below, Tradescantia was dense and deep. It was left undisturbed on this bank throughout the dry season, but gradually gathered in from the outer extent of its invasion in the kanuka canopy below Arena and Cape Honey Flower Banks.

In July 2019 we surveyed further through the canopy and its margin, and found ferns, native shrubs and herbs, and many and diverse seedling trees, including tanekaha, in the light-to-moderate tradescantia past Flame Tree bank.

Pre-intervention:
https://inaturalist.nz/observations?order=asc&order_by=observed_on&place_id=any&subview=grid&verifiable=any&field:GG%20Tradescantia%20manual%20control%20trial=before%20intervention

After other weeds were controlled and ground moisture had increased enough to support native seedling development, Tradescantia reduction on Flame Tree Bank began in conjunction with herbaceous shrub weed control.

During control:
https://inaturalist.nz/observations?order=asc&order_by=observed_on&page=2&place_id=any&subview=grid&verifiable=any&field:GG%20Tradescantia%20manual%20control%20trial=during%20control

BLACKBERRY

Blackberry, though not obvious, was troublesome from the start, its suckers several metres long and spreading through the honeysuckle and kikuyu invasions. Its thorns pierce all but heavy-duty gloves, and arm-protectors needed to be worn to reduce the time spent bathing scratched arms in kawakawa tea each evening. (It was useful to discover, however, that bandaging with a rag soaked in warm kawakawa tea not only soothed and prevented or treated infection, but often drew out tiny broken thorn tips of all types).

Seedlings were also scattered throughout the adjacent canopy margins.

We were pleased to discover that instead of often-unsuccessful attempts to uproot it, the blackberry could be just folded over itself and the stem partially broken, as for honeysuckle, and covered with a thick layer of any plant material. Its roots became weakened and loosened over a few weeks, as we had found earlier with the honeysuckle. This saved a lot of time - and scratches - thereafter.

ALOCASIA, GINGER, ARUM

Alocasia brisbanensis (Elephant's Ear), Arum lily and Kahili ginger, having been temporarily controlled from October to April by cutting of stems or leaves, were thereafter treated the same way as had been found successful with blackberry, ie partially broken down and heavily mulched with a pile of Tradescantia.

Before applying mulch to any shrub weed, the bulk of the shrub weed was reduced as much as possible without a lot of effort: ie ginger stems were bent tightly in several places and folded down, their leaves intact, over the centre of the clump. Arum and Alocasia had their leaves broken off or pushed down, and stems were cut or broken if possible to do so easily.

Alocasia before intervention:
https://inaturalist.nz/observations?order=asc&order_by=observed_on&place_id=any&subview=grid&verifiable=any&field:GG%20Alocasia%20brisbanensis%20control=before%20intervention
Regrowth of those plants after cutting at base:
https://inaturalist.nz/observations?order=asc&order_by=observed_on&place_id=any&subview=grid&verifiable=any&field:GG%20Alocasia%20brisbanensis%20control=Regrowth%20from%20cut%20stem%20bases

During or after heavy mulching with Tradescantia:
https://inaturalist.nz/observations?order=asc&order_by=observed_on&place_id=any&subview=grid&verifiable=any&field:GG%20Alocasia%20brisbanensis%20control=Regrowth%20or%20stumps%20heavily%20mulched%20with%20Tradescantia

BULB WEEDS

Bulbil Watsonia was abundant throughout the canopy margin, and Montbretia throughout the upper Arena. Their current status and methodologies used are discussed here:
https://inaturalist.nz/projects/gahnia-grove-site-summary-and-discussion/journal/26178-bulb-weeds-montbretia-and-bulbil-watsonia

OTHER WEEDS still being controlled in Gahnia Grove include:

ARISTEA ecklonii
Another weed observed abundant in June 2018, and found to be having significant impact on the manuka canopy margin with scattered substantial invasions well into the kauri ridge community under tanekaha, totara and forest understorey. We welcome any experience of the likelihood of complete suppression by increased density of shade as the forest matures. Until then we are suppressing them where mulch is at hand, and uprooting them as soil conditions and time permit - not difficult to uproot once ground is very wet. Even easier if they have previously been covered with eg uprooted pampas, manuka brush, or pine needles.

https://inaturalist.nz/posts/25775-aristea-ecklonii

AGAPANTHUS
See https://inaturalist.nz/posts/25776-agapanthus-june-2019

CALYSTEGIA
We were able to control the anticipated emergence of annual growth on the extensive existing invasion by a common hybrid of the native Calystegia sepium subsp roseata and the invasive (Calystegia silvatica) species. There are numerous occurrences of this hybrid invasion throughout at least 100m of this forest margin.
https://inaturalist.nz/posts/17537-bindweed-calystegia-sp-to-be-next

PAMPAS
Numerous pampas in the manuka/kanuka canopy, and a single clump c.4mH and 3mW on the sunny grass margin, were treated by the easiest and least time-consuming method of bending over and breaking any culms, throwing live and dead foliage over the centre of the clump if possible, and cutting most of the live foliage off the large clump in the grass margin.

One or two subsequent walks through the canopy repeated the suppression of the small ones there till they were easily uprootable.

More interventions over several months were needed to totally uproot a larger clump in a light-break in the outer manuka margin with little shade.

The big one in the sun is gradually rotting on the most-trimmed "Gahnia Grove" side, while the outer side, whose live foliage was retained during summer to avoid the potential fire hazard of loose dry grass, is gradually weakening as a result of ongoing attrition. Water build-up in the centre of the clump is encouraged by keeping a natural vertical channel open in the centre of the clump, so the stem bases are rotting particularly well here in the centre.

EXOTIC PALMS

A single Phoenix palm seedling, c.50cmH in June 2018 and suppressed by partial breaking the main leaves and pushing them down and toward the centre, effectively self-mulching with their own foliage. A month later the weakened and softened leaves were looped and loosely knotted together.

This took only 10-30 sseconds, and there was no significant growth for some months. When regrowth did occur, it was by a single leaf growing through or around the loop. Repeat intervention took only a few seconds and again suppressed it for some months. A third intervention resulted in the seedlings being about the same height in June 2019 as it was in June 2018, but having only one or two growing leaves, the rest being unable to grow.

In July 2019 one leaf had grown above the loop, to the original height of about 50cmH. It was tucked into the loop ia second or two,before we remembered to photograph it, but next time intervention is needed we will tyr to remember to record it. (We are also monitoring and recording some Phoenix palm seedlings being treated by the same method in Kaipatiki Creek).

It is hoped that roots will have been sufficiently weakened by a year or two of unproductive growth for the palm to be uprooted despite the hard dry clay, which the stout and woody tap roots of even tiny palm seedlings penetrate to a considerable depth. In a site with ongoing monitoring and intervention as needed, the repeat interventions take only a few seconds in passing, so if the method succeeds the time required for extermination of the plant will have totalled only a minute or two, with no need for scheduling or equipment, and no physical effort.

-https://inaturalist.nz/observations?order=asc&order_by=observed_on&place_id=any&project_id=gahnia-grove-site-summary-and-discussion&subview=grid&taxon_id=78554&verifiable=any

WEED SEEDLINGS
Weed seedlings occurring in bared ground and among pre-existing native vegetation have preominantly been the same species that were removed in the initial weeding:

A few more CLIMBING ASPARAGUS seedlings occurred among the mature and juvenile native trees, but as yet not as many as were present at the start of the Project a year ago.

Weed seedlings of BRUSH WATTLE, MOTH PLANT and CHF were abundant and continuous in the months following removal of their parents. Brush wattle and Moth plant were expected; the CHF was a bit of a surprise, as NZ info websites had suggested invasion by seedlings was rare. Until July 18 CHF seedlings were not observed more than a few metres from the parent infestation, so it was not technically a new invasion, but there is obviously no problem in the seeds being produced and germinating. Whether many seeds had lain dormant awaiting light is a question that we were not able to answer in our observations, but no seedlings were observed prior to the cutting of the many adult stems.

In late July a CHF seedling was found 20-30m from the site of the original infestation, in bare clay in the manuka canopy margin of the Annexe, where Aristea, Watsonia and honeysuckle and kikuyu had been removed last year.

Even more interestingly, one was then found about 20m within the canopy, the first one seen here. Either it was brought by a bird or other animal who ingested it in the area where the CHF was cut down, or the species sometimes germinates in shade but dies from lack of light.

The benign exotic herbs suppressed most weed seedlings, but hid those that did germinate, so that where wildflowers had grown tall and dense, Moth plant and wattle seedlings weren't seen until they were up to 50cm H. However, they were few, spindly., and easier to uproot from the damper ground among the benign exotics than the dry bare clay areas.

The abundance of Brush wattle and Moth plant seedlings in March was noted here:
https://inaturalist.nz/posts/22520-brush-wattle-and-moth-plant-seedlings-removed-in-marchNew weed invasions occurred during the Project so far included:

SWAN PLANT (Gomphocarpus sp) - two seedlings grew swiftly to 40cmH, in ex-kikuyu ground with a thin surface of wood chip mulch, and among benign exotic herbs. Both were uprooted easily

Cape gooseberry - a few seedlings uprooted, and one or two retained for now as benign exotic herb-cover, to be controlled before fruiting

BLACK NIGHTSHADE (Solanum nigrum) was not noted at the start of the Project, but was probably present among the kikuyu and blackberry. Over summer it became common throughout cleared areas and was retained, its upright single-stem and deep tap-rooted habit beneficial to soil-conditioning, conducive to seedling development in its canopy, and easy to cut down when no longr wanted.

Once these Black nightshade began to flower, we examined each plant for the "umbellate" flowers (all flowers or fruits join the stem at the same point, like an umbrella) of the two native species common in this area, DARK NIGHTSHADE (Solanum opacum) and "AMERICAN" DARK NIGHTSHADE (Solanum americanum), which we had learned of through iNaturalist.

After identifying dozens of Solanum nigrum, at last a Solanum opacum was found, then several more. Later, care was taken not to cull these along with the exotics. It seems likely that dominance of the native nightshade will be achieved by gradual culling the exotic species, before fruiting where possible. It seems likely to be as useful as Haloragis erecta as a nurse-plant for native tree seedlings.

Specimens of S. opacum identified so far have been distinguishable from the S. nigrum specimens on the site by leaf shape and colour as well as the fruit/flower arrangement and characteristics, so we may be able to remove the exotic Black nightshades at an earlier stage from now on, except where it is the only available ground cover and mini-canopy during hot dry weather.

NATIVE SEEDLINGS in Gahnia Grove -

(These search results include repeat observations of some specimens)

In ground released from weed invasion since June 2018:
-https://inaturalist.nz/observations?verifiable=any&place_id=any&field:Native%20seedling%20or%20sporeling=in%20ground%20released%20by%20manual%20weed%20control%20since%20June%202018

In ground released from weed invasion since Oct 2019:
-https://inaturalist.nz/observations?verifiable=any&place_id=any&field:Native%20seedling%20or%20sporeling

All observations of native seedlings and sporelings, including those in the mainly-weed free canopy - ie regardless of impact of weed control:
-https://inaturalist.nz/observations?place_id=128172&subview=grid&verifiable=any&field:Native%20seedling%20or%20sporeling=

This list should of course include the seedlings of the native nightshade Solanum opacum, but we did not learn to recognise the species as seedlings during the year, and could still not be sure enough to identify the seedlings in a recorded observation.

Some of the fun things we don't need to do anything with except enjoy:

MOSSES & LICHENS in Gahnia Grove:
https://inaturalist.nz/projects/mosses-fungi-and-lichens-of-gahnia-grove?tab=observations
and the Wildlife, in case you skipped the link above in relation to Benign exotics herbs:
https://inaturalist.nz/projects/wildlife-of-gahnia-grove

TIPTOE PATH
We continue to build up a 30-40mm wide swathe of woody plant material as it becomes available, with coarser sticks on the bottom preventing bogs and ruts in the clay, eventually to have a smoother surface of dead pampas bases and foliage. Such a "tip-toe" path is necessary for all-weather access to various areas of the site minimising trampling in the ongoing observations and interventions. The relative unevenness and narrowness of the path discourages people who might enter the site from walking as if on a street, ie heedless of the plants, soil conditions and invertebrates at their feet. The perfect "Small Things Observation Path", but not so good for looking at tree tops or birds in the sky:)

For all observations recorded, grouped geographically, see an Overview (Map at bottom of page) and Projects for each of the various sub-sites and a few other other criteria in Gahnia Grove.

https://inaturalist.nz/projects/gahnia-grove-umbrella-project

Posted on July 20, 2019 10:34 by kaipatiki_naturewatch kaipatiki_naturewatch | 0 comments | Leave a comment

July 16, 2019

Cape Honey Flower

In June 2018, several Cape Honey Flower (CHF) flower stems stood about a metre high throughout 2 or 3m of the mown kikuyu edge.

Closer observation revealed their many low curving stems were actually about 3mH, up to 4mL and densely covering c.10x10m, intertwined with honeysuckle, blackberry and kikuyu over a light ground cover of Tradescantia.

Some views showing it before intervention:
https://inaturalist.nz/observations?order=asc&order_by=observed_on&place_id=any&subview=grid&verifiable=any&field:GG%20Cape%20Honey%20Flower%20manual%20control=before%20intervention

In early November all the CHF stems were sawn off at or near ground level by a contractor provided by the Community Ranger to assist us. The leafy tops were cut off and piled over the stumps for some weeks, this wood and foliage providing the only ground cover over large areas of otherwise bare clay during a not dry summer.

The top of CHF Bank, during kikuyu and honeysuckle control in July 2018, and (towards the bottom of the page) in 2019, with the first replacement vegetation at the top of the bank, and during Tradescantia control on the lower bank:
- https://inaturalist.nz/observations?order=asc&order_by=observed_on&place_id=any&subview=grid&verifiable=any&field:GG%20Cape%20Honey%20Flower%20manual%20control=during%20control

A few weeks after the stems were sawed off around November 2018, new leafy stems began to appear. Cut foliage had now dried and shrivelled, so the new CHF stems were allowed to grow on the exposed bank top over summer, shielding at least a small part of the ground from the hot dry sun and wind until alternate ground cover developed.

Regrowth of root suckers:
https://inaturalist.nz/observations?order=asc&order_by=observed_on&place_id=any&subview=grid&verifiable=any&field:GG%20Cape%20Honey%20Flower%20manual%20control=regrowth%20root%20suckers

Cut stumps heavily mulched with wet plant material eg Tradescantia:
https://inaturalist.nz/observations?order=asc&order_by=observed_on&place_id=any&subview=grid&verifiable=any&field:GG%20Cape%20Honey%20Flower%20manual%20control=heavily%20mulched%20roots%20assisting%20suppression

Once exotic herbs became established the CHF regrowth was cut as it appeared. As CHF regrowth was vigorous, decaying plant material was scarce, and Tradescantia was dense a few metres further down CHF Bank and on the adjacent Flame Tree Bank, some Tradescantia was gathered and piled on the cut CHF stumps. This heavy mulch of Tradescantia was intended both to suppress the CHF regrowth and to maintain ground moisture for the surviving native trees through summer - karamu, mapou, and two kawakawa whose leaves had yellowed shortly after removal of the previous weed cover.

On the steepest part of the bank Tradescantia mulch was not used, as the mulch would have been unstable and its control time-consuming, particularly in winter run-off. On these steep banks, Regrowth of the CHF plants growing laterally from steep banks is being suppressed by ongoing removal of small shoots, with a little non-invasive mulch eg thinned herbaceous plants that can be "hooked" on the CHF stumps.

The cut CHF stems are hollow, presumably collect water, and are now now decaying. The growth of new stems from the roots has declined by about 90% since December, but we expect ongoing monitoring and regrowth-removal will be necessary for some time.

Posted on July 16, 2019 01:34 by kaipatiki_naturewatch kaipatiki_naturewatch | 0 comments | Leave a comment

July 15, 2019

Bulb weeds - Montbretia and Bulbil Watsonia

We cover both these bulb weeds here as the young leaves are often indistinguishable, so they get treated together. However, while montbretia is usually easily uplifted entire when it is mature, Watsonia bulbs are almost always impossible to uplift, at least here in this hard dry soil among shallow tree roots.

So eradication is aimed for by very different methods. A later report will cover the method being used for Watsonia in July 2019 throughout a larger area of canopy and grass margin downhill of Gahnia Grove, after the year's observations and various methods of control in the manuka canopy and its grassed margins of Gahnia Grove, where all Watsonia were suppressed by either cutting or tearing off leaves, or trampling and mulching. After almost no evident leaves through summer and autumn, a new crop of leaves started to appear in July 2019.

https://inaturalist.nz/observations?order=asc&order_by=observed_on&place_id=any&subview=grid&verifiable=any&field:Gahnia%20Grove%20site%20monitoring%20views%20-%20%22smv%22=smv13

Watsonia is very dense throughout the partial shade of the manuka canopy margins from the roadside to the lower recreational grass margins at the entry to the top forest path. Deeper within the forest, Watsonia becomes scarce to absent - whether because the invasion has not yet progressed that far into the forest, or because an earlier invasion has been suppressed by increasing shade, we do not know.

In places there is not a single point of earth without a leafy or hidden bulb. With bulbs occupying the ground so densely in many places as to prevent seedling development, we do not know whether the young solely-manuka canopy margin will develop deep shade sufficiently quickly to suppress the existing dense ground cover by Watsonia without intervention.

Observations of Watsonia in Gahnia Grove from May 2018 to the present:
https://inaturalist.nz/observations?order=asc&order_by=observed_on&place_id=128172&subview=grid&taxon_id=72425&user_id=kaipatiki_naturewatch&verifiable=any

We are not familiar with their seasonal and reproductive habit yet, but after removal and/or suppression of all leaves in the Gahnia Grove canopy margins, we saw no evidence of regrowth until the drought broke recently with autumn-winter rains. Over the same period, thousands of Watsonia wilted and dried along the outer canopy margin without apparent intervention. These were presumably immature plants, since bulbils have been seen only on a few plants which attained over a metre in height.

Montbretia
In most soil conditions of our experience, mature Montbretia bulbs are very easily uplifted, even in handfuls, by pulling their leaf tips, and are effectively controlled by dropping them in piles anywhere there is not a native plant. When they reshoot they are easily uplifted again, this time en masse. The development of leaf combined with failure of piled bulbs to reach nutrition consumes their stored energy, and the mass of bulbs is gradually replaced by the accumulated rotting leaves and bulbs.

This method of gradual eradication and decomposition in situ suits our Methodology, which depends on ongoing successive monitoring and intervention. However, in the interests of developing a transferable method requiring the least monitoring, at Gahnia Grove in Spring 2018 we collected all uplifted bulbs, including the few Watsonia bulbs that were able to be lifted, and cable-tied them all together in a number of heavy-duty plastic bags.

Watsonia bulbs are said to be prone to rotting in damp storage. Over summer and autumn some of the Watsonia bulbs did decay in the bags, (we have not examined the rotting mass closely yet) but many Montbretia bulbs appear to have survived in a viable condition.

On another site, we recently observed Montbretia bulbs buried both under and in large Tradescantia weedbags and in black kleensaks. All the Tradescantia had long decomposed, but some Montbretia bulbs had new green shoots shortly after release from burial.

Sone Montbretia bulbs may have decayed along with the Tradescantia, but the observation suggests disposal in water, eg barrels, is necessary for unmonitored decomposition.

We tipped out the bags of rotted foliage and mixed bulbs and will, for now at least, revert to our earlier method, pleased to have easy access to shooting bulbs in passing, and the ease of throwing them onto the nearest pile rather than having to drag along a bag for collection. We also prefer the appearance of the site unspoiled by inorganic human artefacts.

Posted on July 15, 2019 23:44 by kaipatiki_naturewatch kaipatiki_naturewatch | 0 comments | Leave a comment

July 12, 2019

The Annexe and Glade margins of Manuka canopy

Grasses being mown in the large recreational area bordering the dense manuka canopy include Axonopus fissifolius, Paspalum dilatatum, Yorkshire fog, Agrostis capillaris, kikuyu (not dominant in the mown sward, but dominant on the margins among, and climbing, the native trees and shrubs) interspersed with seasonally-evident docks, Prunella, dandelions, Juncus articulatus, Lotus corniculata, Bellis perennis, White clover and others.

Among the manuka and scattered karamu of the margin beyond the edge of mowing, Vasey grass (Paspalum urvillei), Ox-eye daisy and Catsear (Hypochaeris radicata) are also common.

Our strategy to date has been to

1. Remove or control aggressive exotic weeds threatening the trees, eg honeysuckle (done) and Watsonia and Aristea ecklonii, Blue corn-lily (done, with 2nd generation control ongoing), kikuyu, Vasey grass.

2. Assist the development of increasingly dense shade and shelter of the manuka canopy edge, to help suppress current and future weeds and maintain moisture through dry periods, supporting ongoing multiplication and growth of the already-present kanuka, Coprosma robusta and lucida, ti kouka, totara, mingimingi, tanekaha, Pseudopanax arboreus and crassifolius, sedges and rushes, native lobelia, Shrubby toatoa, and other forest and scrubland species.

To assist the development of juvenile trees in this margin, we have replaced line-trimming with manual weeding.

Our next instinct to help increase the density and diversity of vegetation in this margin, has been to enrich the soil, which has highlighted the following issues:

Little leafy , or any, vegetation is being produced here. Even the exotic grasses are slow-growing and diminutive, providing insufficient plant material to effectively suppress the remaining Paspalum and other grasses, Creeping buttercup and Watsonia, whose control remains an ongoing though infrequent task.

(The scant kikuyu present here is actually helpful, as its long unrooted stolons and uncut stolons are easily pulled back from the shady forest edge, providing mulch, whether living or dead, to suppress the other species).

Rather than follow this instinct to enrich the soil, might it be better to maintain the present dry ridge character of this margin, controlling weeds only by uprooting when possible and cutting when required for fire prevention, using only the minimal mulch available?

With this minimal-intervention we would watch to see what Nature would establish here to achieve succession to densification of canopy by decreased light invasion and dessication from the large sunlit area of adjacent, of mown grass well-used by residents and dogs for recreation.

By controlling invasive, mainly mat-forming herbs and grasses, we are enabling the wild native regeneration of the margin.

By not mulching heavily to improve the nutrition and hydration of the soil, we presumably restrict the developing vegetation to dry ridge species, perhaps in due course even the natural replication of lichen and moss fields of which, we are told, this forest holds some of the best examples in Auckland.

In the meantime, should we see the emergence of fungi, mosses and lichens native to this dry kauri ridge and flourishing under podocarps eg tanekaha nearby, we would watch for and support the natural development in this margin of such precious and endangered habitat.

Any shared thoughts or experience would be welcome.

Posted on July 12, 2019 21:38 by kaipatiki_naturewatch kaipatiki_naturewatch | 0 comments | Leave a comment

Benign exotic herbs

Benign exotic herbs in ecological restoration are those which do not suppress native vegetation, or only suppress seedlings and can be easily controlled if and when needed, by cutting down, trampling or uprooting.

Many other exotic plants are also benign if sufficient quantities of mulch to suppress that species are readily at hand when needed, eg when native seedlings arise or grow larger and are ready to occupy that space or need access to light, or root space.

Until the natives reach that stage, the exotic herbs provide ground cover and shelter from sun and wind, reducing dessication and weed invasion. Their roots penetrate the soil, aerating it, allowing subsequent seedlings to reach hydration and nutrition more readily, and during their decomposition extending the depth of the topsoil and quantity of humus available to subsequent revegetation.

From observations of the surrounding area from June 2018, by September 2018 our restoration plan for Gahnia Grove had developed to include extending our previous experiences of benign exotics in revegetation within the dripline of forest margins, into a monitored Trial of the use of Benign exotics in wild revegetation over larger areas.

The situation in Gahnia Grove was one of dense tree/shrub/vine weed infestation throughout areas up to 10x10 metres without a single native plant. The nature of the Japanese honeysuckle and blackberry required total control to make ongoing control manageable in the time available.

During the control of these weeds it was discovered that Japanese honeysuckle and blackberry, and (later) ginger, Alocasia, and Arum lily, could be controlled more efficiently by only partial uprooting, leaving the root heavily mulched with its own stems and suckers, with the addition of cut stems, uprooted material, and in fact any other plant material available. The roots buried under such mulch became weakened over weeks or months depending on moisture in the mulch pile.

By a variety of these means, the uprooting of these plants was complete over large areas by September 2018, and the previously-sprayed kikuyu margins were also bare of vegetation to compete with the bordering kikuyu.

The plan was to allow dense revegetation of both the kikuyu margins and the wide areas cleared of shrub and vine weeds, restoring ground cover as soon as possible to prevent dessication and weed invasion until existing canopy spread, and new native vegetation was established, to fill those functions in both kikuyu margins and on the wide banks below.

We watched the bare clay anxiously in Spring to see what, if anything, would arise in the hard, bare areas of clay, in some places heavily diluted with roading mix, (which we subsequently learned are likely to have created these banks during levelling and widening of Glenfield Rd, with subsoil and roading materials perhaps having been pushed back onto these banks, explaining the gravel throughout the top 10cm of soil of the kikuyu margin, isolated areas of granular material, and cracks below sharp drops below the road in some places).

The first plants to appear were wild carrot, common vetch and cleavers. The first to survive were broad-leaved docks and creeping buttercup, which were immediately suppressed by mulching lightly with available weed material, including that of their own species; ie scooping the leaves of a few docks provided the material to suppress hundreds of tiny dock seedlings nearby; tearing a few handfuls of leaves off Creeping buttercup plants, and uprooting any plants in soil loose and damp enough to allow it, provided mulch for adjacent buttercup plants. A week or two later, the mulched plants were loose enough to be uprooted, combined with those mulching them, and used elsewhere.

We were pleasantly surprised at how successful this was in keeping areas clear of unwanted weeds until more congenial species arose - fresh crops of the wild carrot and vetch, with oxtongue, Scarlet pimpernel, and all the others seen here:

https://inaturalist.nz/observations?captive=any&place_id=any&project_id=30419&subview=grid&verifiable=any

The first areas to establish cover by benign exotics were under the few surviving karamu or manuka, or in areas where a little humus had been created by the decomposition of honeysuckle, blackberry, kikuyu and other "first-generation" weeds.

Tall Verbena (intially thought to be bonariensis, but apparently V. incompta) and Verbena litoralis were a later, and much denser, arrival. Whether the seed existed in the topsoil, or was windblown from nearby plants since June 2018, remains an interesting question.

Calystegia silvatica (x sepium spp roseata, ie the hybrid native/exotic common along this forest margin) arose suddenly and, as expected, aggressively, and was actively uprooted where soil was loose, or broken off, as it threatened to suppress the other exotic herbs.

All the exotics known by experience to be helpful, or considered possibly benign were supported in developing dense communities of their own ""choosing", with very little assistance by active weeding, resulting in the surprising spontaneous suppression of Creeping buttercup, Broad-leaved dock, trefoils, Vetch and other weeds initially being monitored as possibly obstructive to native revegetation.

Posted on July 12, 2019 21:36 by kaipatiki_naturewatch kaipatiki_naturewatch | 0 comments | Leave a comment

Bulbil Watsonia control

New shoots are appearing throughout manuka canopy and its light-invaded margins bordering mown grass.
https://inaturalist.nz/observations/27897208

This follows some months - during summer/autumn drought - with no evidence of Watsonia 9-12 months following suppression by manual removal or mulching of all leaves, which were present throughout the Annexe and the manuka Canopy below Annexe and Apron, eg MAy 31, 2018
https://inaturalist.nz/observations/18830171

This area, c.20x20m, is of dense manuka, (becoming manuka/kanuka at the Northern end ie older regen) with light breaks throughout the mature manuka canopy.

Watsonia will be suppressed ongoing by leaf-removal or mulching where native seedlings, sporelings, juveniles or mosses exist, and elsewhere as convenient, but eradication is likely to depend on increasing shade through densification of the revegetation throughout the now c. 50m margin of manuka canopy in this restoration site with dense long-standing Bulbil Watsonia infestation, some of this area not having been included in Gahnia Grove till now, and having had only occasional ad hoc intervention on Aristea and Watsonia while suppressing numerous small pampas and a few shrub/tree weeds.

Posted on July 12, 2019 21:33 by kaipatiki_naturewatch kaipatiki_naturewatch | 0 comments | Leave a comment

Aristea ecklonii

Background/history in Gahnia Grove:
https://inaturalist.nz/posts/17481-stinking-iris-correction-blue-corn-lily-ie-aristea-ecklonii

End of year result:
These plants were not evident at all in the Trial area over late Spring, Summer and Autumn, having been uprooted fairly easily throughout the site once the ground became thoroughly wet. Seedlings became common with first rains in about April, but were so fiddly to pull out that most were either mulched with a nearby handful of weeds, or left. They self-thinned to a certain extent, and the remainder are being easily broken off, and as the ground becomes wetter, uprooted entirely.

Large plants remain in the canopy below Gahnia Grove's Year 1 boundaries, but will be treated in the same manner if we extend our weed control down the ridge to protect the Tanekaha moss beds and surrounding kauri ridge community, including the margin of the mown area where the density of these is highest, and the forest path where there are scattered large groups of Aristea.

Posted on July 12, 2019 21:32 by kaipatiki_naturewatch kaipatiki_naturewatch | 0 comments | Leave a comment

Agapanthus June 2019

Background/history in Gahnia Grove:
https://inaturalist.nz/posts/22953-agapanthus-trialling-no-dig-no-chemical-eradication

One-year assessment:

There are a few stumps remaining in place. Throughout the dry hot summer they continued to shoot from time to time, but now leaves rarely emerge. They continue to be torn off or suppressed with an uprooted or cut exotic herb or two.

When the ground is thoroughly wet we expect to be able to wiggle some of the weakened tubers loose and uproot them.

Posted on July 12, 2019 21:30 by kaipatiki_naturewatch kaipatiki_naturewatch | 0 comments | Leave a comment