Diario del proyecto Gahnia Grove - Site summary and discussion

Archivos de diario de julio 2019

04 de julio de 2019

Japanese honeysuckle control in Gahnia Grove June 2018-19

Observed pre-intervention and during control

YEAR ONE - some side-by-side views showing honeysuckle control

smv3: Lower Arena

smv4: Lower Arena

smv16: Glenfield Roadside under Flame Tree

smv17: Top of CHF Bank, just below kikuyu roadside; the karamu

Here are some of the observations of honeysuckle in Gahnia Grove during the first year of the project, sorted by date of observation from June 2018 to June 2019. (While scrolling down the thumbnails you may need to wait a few seconds for more to load)

Our initial intervention, over a few months, was the cutting through and, where possible, uprooting, of the vast mass of thick honeysuckle in the Arena (an area of about 10m x 10m with dozens of root-centres, each with multiple stems up to 6cm Diam, hundreds of intertwining, many-noded runners on the ground and in outer canopy margin and covering a dozen small (2-3mH) native trees, the outer margin of this infestation extended by slender ground runners a further 7m into forest floor, long kikuy, or dense blackberry, ginger and Cape honey flower) an astonishingly efficient technique for manual control of a large area of honeysuckle with many hidden roots and runners tangled and hidden in dense ground cover by herb and herbaceous shrub weeds, with few native trees and no other native vegetation.

The separation of kikuyu and honeysuckle being impractical, we treated ground honeysuckle the same as kikuyu, ie pulled it back on top of itself for suppression and root-rotting by self-mulching. We did not expect this to control the honeysuckle, but were surprised how much was gained by the delay in attempts to uproot it, the roots buried by mulch eventually becoming weakened and able to be uprooted without much effort.

Building on the results of this discovery, we invested a few hours of the contractor time provided by Community Facilities to assist us, in the similarly-effected suppression of the 10mx 20m of tree-covering and ground-lying honeysuckle on Flame Tree Bank, which would otherwise have overtaken our area of restoration.

Flame Tree Bank at the kikuyu margin, where honeysuckle covered a hoheria, a hebe, and two karamu

First it was cut from the few trees on Flame Tree Bank, leaving Tradescantia and Calystegia with increased dominance as ground cover

LOG-ROLL FORMATION
The loose unrooted or cut stems were drawn towards their source and away from the area being cleared, until the mass could be rolled up, forming a "log"about a metre high and several metres long. One ran up and down the bank, the other across the bank at the top, beneath some karamu now partially released from honeysuckle, with honeysuckle regrowth from among their roots requiring occasional intervention to keep it contained.

For the next few months, the log-rolls suppressed all honeysuckle on Flame Tree Bank except a little regrowth from under or through them, which was cut or pushed back onto the roll.

Both logs were rolled up against low banks which largely hid them, and over summer and autumn they became invisible as Calestegia and and shoots of honeysuckle grew through and out from under them, so the rolls are not obvious in any of our observations. Though functioning extremely well in suppressing the invasion, they are barely detectable here.

By about May, reaching for a piece of regrowth from under a roll revealed that the lower material had dried and then rotted, could easily be pushed back en masse, and the regrowth was easy to uproot from the moist loosened soil beneath the roll.

In this way several square metres of humus-rich, weed-free soil were released to seedling germination during autumn, resulting in benign exotic herbiage beneath the released karamu, now leafy, fruiting and visited by tui.

Among the first herbaceous plant seedlings were shrubby toatoa, Haloragis erecta, which were supported by culling of exotic herbs where necessary to maximise the toatoa.

This bed of toatoa now hold a few dozen of ti kouka and karamu seedlings. It is the first area of dense weed invasion to hold more native plants than exotic, though the seedlings' ongoing development my depend on release from the adjacent benign herbs in due course.

Areas of Gahnia Grove previously occupied by honeysuckle log-rolls or piles, now rotted and the resulting humus supporting wild native vegetation.

KNOTTING cut stems:
A method of suppression used occasionally where roots cannot be accessed and burial under mulch is not possible

SEVERED STEMS REGROW
We were amazed by Japanese honeysuckle's ability to leaf vigorously not only on cut vine remaining in trees, but on short sections of woody stem weeks after being completely severed at both ends

Regrowth is much harder to control where cut stems cannot be suppressed by mulch.

Publicado el julio 4, 2019 05:09 MAÑANA por kaipatiki_naturewatch kaipatiki_naturewatch | 0 comentarios | Deja un comentario

10 de julio de 2019

Exotic palms in Gahnia Grove and Tanekaha Ridge

Found in the last month in the regenerating kauri forest on Tanekaha Ridge, especially in deep pine needle litter with few other plants, but also in deep moss (native and exotic) beds among dense tanekaha seedliings-to-c.6mH, and mingiming/pigeonwood/gleichenia/coprosma lucida at all stages

Bangalow - about 40 - mostly c.10cmH, one 40cmH
Phoenix - about 20 x 20-30cmH,
Fan palm or Chusan - 3 x 10-20cmH

Publicado el julio 10, 2019 08:11 TARDE por kaipatiki_naturewatch kaipatiki_naturewatch | 0 comentarios | Deja un comentario

12 de julio de 2019

Side-by-side site-monitoring views (smvs) one year after start of site-based manual restoration

Site monitoring views made from a similar viewpoint over a period of time.
Many of these will also have a "Linked observation" Field at the right of the observation, linking the "Before" and "after" views directly.
Note that iNaturalist crops thumbnail images to a square, so the view may be partially hidden in the thumbnail. Opening each observation in a new browser tab allows simultaneous viewing of both whole images.

smv1: Arena

smv2: Tiptoe path through Apron, from Arena

smv3: Ti kouka - Lower Arena/CHF Bank

smv4: Lower Arena canopy margin

smv5: Apron kikuyu

smv6: Tiptoe path Apron to Arena

smv7: CHF Bank

smv8: Wide view of CHF-Arena Kikuyu Margin

Publicado el julio 12, 2019 08:26 TARDE por kaipatiki_naturewatch kaipatiki_naturewatch | 0 comentarios | Deja un comentario

Woody tree/shrub weeds

Tree/shrub weeds present in Gahnia Grove in June 2018:

Brush wattle - 2 x c.5mH, both felled by Wildlands in their 2018 annual Eskdale Reserve weed control operation. One, c.15cmD, was felled without herbicide at our request, and the subsequent death of the stump without use of herbicide was recorded here

We thank Wildlands for their collaboration in this Trial, which reflected our 1997-99 experience of custom and practice in the control of black and brush wattle, and was conducted to build knowledge of a no-cost means of reducing pesticide use.

Tree privet - follow their earlier "progress"

We eventually felled the largest one (c.3.5mH) since after ringbarking at the only convenient point, half-way up, its new growth occurred in the few centimetres between it and the fast-growing native sapling nearby. It has not required intervention again yet, but we expect to continue to pick off new shoots for a while.

Chinese privet

The 3-4mH Chinese privet did not immediately respond to ring-barking, and though we are told by a Texan iNat correspondent that death would likely occur over three years, when faced with its abundant fruit crop we cut almost through the remaining branches, letting them fall to the ground under their own weight and continue to fruit there, where seedlings can easily be suppressed or uprooted as a group.

Elaeagnus and Cotoneaster

Several Elaeagnus and cotoneaster juveniles under canopy, or amongst dense foliage of a similar height, were suppressed by cutting, breaking down and leaf-stripping in June 2019, and the small amount of regrowth since was treated in the same way.

The largest Elaeagnus died, and the smaller one was last seen as a short slender stem trying to escape the shade of a lush leafy mapou...unsuccessfully, as it was broken down once again.

Brief easy repeat operations are expected to result in death or uprootable trunks within a year.

Prickly hakea

A single prickly hakea (Hakea sericea) c.4mH was found prostrate and partially uprooted under moderately dense kanuka/ponga canopy. the cause of its demise is unknown, but it was completely manually uprooted by the contractor assisting us for a few hours in Spring 2018.

Publicado el julio 12, 2019 09:26 TARDE por kaipatiki_naturewatch kaipatiki_naturewatch | 3 comentarios | Deja un comentario

Agapanthus June 2019

Background/history in Gahnia Grove of Agapanthus control in Gahnia Grove here

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.

Publicado el julio 12, 2019 09:30 TARDE por kaipatiki_naturewatch kaipatiki_naturewatch | 0 comentarios | Deja un comentario

Aristea ecklonii

Background/history of Aristea control in Gahnia Grove
here

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.

Publicado el julio 12, 2019 09:32 TARDE por kaipatiki_naturewatch kaipatiki_naturewatch | 0 comentarios | Deja un comentario

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.

Publicado el julio 12, 2019 09:33 TARDE por kaipatiki_naturewatch kaipatiki_naturewatch | 0 comentarios | Deja un comentario

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.

Publicado el julio 12, 2019 09:36 TARDE por kaipatiki_naturewatch kaipatiki_naturewatch | 0 comentarios | Deja un comentario

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.

Publicado el julio 12, 2019 09:38 TARDE por kaipatiki_naturewatch kaipatiki_naturewatch | 0 comentarios | Deja un comentario

15 de julio de 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 clay 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.

Here are observations of a typical section of Watsonia-dominated space manuka-margin before and after a season of ongoing suppression.

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.

Publicado el julio 15, 2019 11:44 TARDE por kaipatiki_naturewatch kaipatiki_naturewatch | 0 comentarios | Deja un comentario