Gahnia Grove - Site summary and discussion's Journal

Journal archives for September 2018

September 2, 2018

The commercial practice of site-based comprehensive weed control

Inseparable from the methodogy as practised at Kaipatiki Creek and Gahnia Grove are the observation, exploration, discovery and study that are integral to working with a living, growing piece of wild vegetation. Time recorded includes time contemplating, pondering and enjoying the ongoing changes. Also logged are hours of offsite research to assess the implications of the discoveries made, and amend restoration plans accordingly.

This whole process is as much recreation and citizen science as labour.

It is difficult to say how much of the time spent in these activities is necessary to achieve successful restoration (ie without loss of species or habitat). however, we note that if this practitioner, having learnt from this project, were employed to restore a similar environment and plant communities, they would probably log about 60% of the time spent; ie would expect to be able to produce the same results without the additional hours spent discovering and learning.

Since the practice of this Methodology as an occupation does not yet exist, the required knowledge-base and manual skill-set are rarely found combined in the workforce or community. So the additional hours would have to have been spent at some stage for the necessary professional development.

Our assessment so far is thus that :

  1. A system needs to be developed to attract and train those with the necessary aptitudes.
  2. Until such training is developed and implemented, and its graduates employed, the most economical way to achieve restoration without loss of habitat and biodiversity might be to team a specialist ecological restoration contractor with one or a few volunteers for combined project-planning, enabling the contractor to reduce or avoid chemical use through the ongoing manual follow-up by the volunteer, who would enjoy an uncontaminated environment in which to watch and assist the ongoing spontaneous regeneration and increasing diversity.

It is observed that contractors are currently required to use enough chemicals to ensure there is little or no regrowth during a year.

It is also observed that many chemical operations are, despite best practice, unable to fully discover and treat all parts of all invasions, so that regrowth often occurs anyway.

Contractors relieved of current expectations for total single-visit chemical control could be teamed with volunteers trained to monitor and contain regrowth and to remove seedlings while still easy to uproot. Species loss would be less, environments would have more appeal for volunteers, and eradication of many invasions would be achieved, instead of repeated treatments of the same invasions, and expensive control of matured specimens which could have been pulled out easily a year before.

We recognise that contractors are currently attempting to achieve such effective weed control currently, but with the number and size of natural areas in Kaipatiki, at least, we do not believe current budgets can avoid the waste and destruction of unnecessary chemical use and the expensive future maturation of current young invasions.

We note that the current weed control contract system for this area is only a year or two old, and we continue to learn how it is practised and to observe and assess its results.

Posted on September 2, 2018 09:59 PM by kaipatiki_naturewatch kaipatiki_naturewatch | 0 comments | Leave a comment

Gahnia Grove's Progress Report for August 2018

August: 8 hrs liaison and research; 10 hrs monitoring and documentation; 10.5 hrs of weed control: Total: 28.5

YTD: 33.5 hrs liaison and research; 51.5 hrs monitoring and documentation; 67 hrs of weed control; 4.5 hours pathmaking: Total : 157

NB Most of the hours monitoring are necessary to establish results for those who have not previously observed them, and this time will not be required once the Methodology and practise are well-understood.

Regarding the proposed application of this methodology by both contractors and volunteers, please see "News".

August Site report:

Path: Parks advises that there is no need to maintain public access through the Grove, so the pathmaking is now simpler, confined to defining a narrow track between apron, arena and canopy, made non-slip with woody material and dead pampas.

Manuka/kanuka canopy: we have learned that much of the inner canopy is in fact Kunzea robusta (Kanuka)

An interesting suspected exotic naturalization observed: a lily perhaps?
https://inaturalist.nz/observations/16127454

All Pampas, large and small, have been suppressed by self-mulching, with no signs of resurgence. This is such a quick, easy process we would like to continue it throughout the canopy downhill, where pampas is also common, though it will probably die out if shade is successfully increased.

Watsonia leaves have been pulled off throughout most of the canopy in Gahnia Grove, leaving most bulbs in the ground, mulched with the leaves and in some cases forest debris eg manuka wood. An area of dense Watsonia remains to be treated similarly.

A few bulbs with leaves left on and thus mulched some weeks ago, are now able to be easily pulled up. However this is time consuming, so self-mulch has been left in place throughout, minimising piles to leave maximum room for seedling development.

Honeysuckle runners hidden in the forest floor continue to shoot rosettes at nodes, and to emerge frm the bases of tree trunks. They are being uprooted where possible, and partially-broken and mulched where uprooting is not possible.

In one interesting case, a stout vine is firmly embedded in the wood of two forks of a kanuka/manuka trunk: https://inaturalist.nz/observations/16023368

Kikuyu control:

Outer edge - The edge of the mown kikuyu area on the Outer, ie road side of the harakeke and island plantings has not yet grown long enough for pullback. There is no obvious regrowth in the sprayed edge. Occasional rhizomes have been discovered by disturbing the soil surface there, but an extensive search has not been made, due partly to the level of chemical contamination of that soil, and to the difficulty of locating deep rhizomes. The current plan is to control them as they develop above ground, probably letting them grow long enough to self-mulch by pullback.

Top of Arena - Kikuyu is slightly further reduced in width due to pullback from the planting, ie the harakeke and the trees in the Arena. It is not yet long enough to pull back, so a kikuyu "path" remains. We continue to gradually extend a defined kikuyu-free area.

The Arena bank - as for July: There is no evidence of live kikuyu and there are several square metres of bare clay. However, small areas of live rooted rhizomes remain, mulched heavily with their own live stolons and rotting foliage, with intermingled honeysuckle vines, some still rooted, some cut or uprooted. These mulch piles are heavy, which helps rotting but makes moving the material difficult.

Apron
Kikuyu rooted in several small areas, has been further reduced, mulched with its own attached stems and with semi-rotted kikuyu from other areas in the Apron.

Creeping buttercup widespread and being spot-mulched.

Sonchus oleraceus (Common Sow-thistle, sometimes called "puha" in NZ though not native) collected from neighbouring street berms and sown as a green mulch, easy to remove when necessary

Seedlings:
Native - 1 ? Haloragis erecta - not observed again, though 1 has been found under canopy

Exotic - [As in July: Fumitory, Prunella vulgaris, wild carrot and catsear - not much grown, continue to be retained , Also vetch sp. and Common daisy. The daisies may need to be controlled fairly early as they lie close to the ground and can be hard to pull out, but at the moment they are preferable to the inevitable creeping buttercup of which some sturdy specimens are already present in most areas. The vetch may or may not need to be removed depending on its competitors.
Lesser trefoil/Medicago sp is emerging in places and being pulled out as much as possible as it can be agressive and is virtually impossible to completely remove from among roots or from tussocks.]

Summary of observations of planted trees

Arena:

Hoheria - 1 x c2mH Hoheria - still flowering, but foliage is stiff and shrunken. What is indicated by the large amount of lichen on the trunk?

Karamu - 5 survivors of honeysuckle canopy - extremities which had extended beyond honeysuckle coverage are leafing out. 1 tree is not developing foliage at all, just retaining its few, terminal, misshapen and discoloured leaves

Manuka - foliage surviving honeysuckle coverage continues to flower

Ti kouka - c4mH trunk released from honeysuckle still growing strongly

Putaputaweta - 3x, all growing slowly

Kawakawa -1 x1.5mH - fruit developing

1 x1mH at bottom of Arena - no further development of scant foliage

Weeds

Arena

Blackberry- cut stems continue to shoot new leaves where not mulched. Being uprooted where where discovered under mulch with roots weakened

Montbretia - continued uplifting of dense clumps of bulbs where loose. Stored in thick used plastic bags (from 2005 compost purchases), including damp material and firmly fastening with cable tie to induce rotting

Creeping buttercup - arising throughout Arena, being mulched as found

Unidentified - seedlings continue to arise in bare clay, none mature except 1 ?manuka

Island Planting

Elaeagnus, Cotoneaster and Japanese spindle tree - no further regrowth yet

Moth plant - occasional seedlings uprooted or broken off

Common ivy - no more found

Climbing asparagus - 1 or 2 more seedlings found and pulled out

Manuka canopy

Blue corn lily (previously ID'd as Stinking Iris) - where uncovered under mulch in continued uprooting of honeysuckle , these have weakened roots and are easily removed on Annexe margin and under canopy nearby

Watsonia, abundant throughout - see above

Kahili ginger – one small leaf-bud of regrowth observed, removed with two fingers

Several Elaeagnus and Cotoneaster to c1mH - stems leaf-stripped, twisted and looped. No regrowth yet.

Canopy below Arena:

Single Chinese privet given another partial-breaking of reachable branches, further releasing adjacent mapou

Brush wattle seedlings 2-10cm , several more scattered, removed as encountered
ginger seedlings - occasional, removed

Arum lily - no longer evident

Phoenix palm - no change since 2nd intervention, stems still looped

Flame tree - Growing; standing control approved and being arranged by Parks

Agapanthus - minimal change, self-mulching continues with pulled leaves

Ginger - several small stands self-mulched and unchanged

Posted on September 2, 2018 11:25 PM by kaipatiki_naturewatch kaipatiki_naturewatch | 0 comments | Leave a comment

September 10, 2018

Scrambling Pohuehue planting of perimeter planned for next autumn

Parks Community Ranger has agreed to arrange planting of Scrambling pohuehue (Muehlenbeckia complexa) at approx. 30cm intervals around the permieter of the canopy margins of the site, to prevent litter, dumping, trampling by people and some weed invasions.

Since it would be very difficult to weed through the dense network of vines once the Pohuehue is grown, it will presumably be necessary to have weed-free margins before planting. It has been suggested that there should have been a year of eradication of weeds before the planting.

Any experience of this issue would be welcome.

Wild ecosourced pohuehue is being sought in the catchment.

Posted on September 10, 2018 06:48 AM by kaipatiki_naturewatch kaipatiki_naturewatch | 0 comments | Leave a comment