Contractor Assistance - Missions accomplished

24 hours work at our direction was contracted by AC Parks with a Biodiversity Management student previously recommended to us for Botanical Survey work. Manual weed removal and initial control was mainly on the steep and initially inaccessible Cape Honey Flower (CHF) Bank, between the bank directly under the primary Flame tree stand and Gahnia Grove's Arena.

For observations of CHF Bank from June 2018 to January 2019 see:
https://inaturalist.nz/observations?order=asc&order_by=observed_on&place_id=128172&project_id=gahnia-grove-chf-bank&subview=grid

The CHF was all sawn off as near as possible to the ground, and the wood, with any foliage attached, placed in piles. An initial session in October was followed up in November and December by removing some remaining CHF stems and any loosened stumps. Piles were relocated in the interim to rot more of the blackberry and to allow access to remaining roots.

The many curving stems of CHF, up to 4m long, made the bank difficult to traverse or weed even after being cut down, and their thin hollow stems created a lot of dry flammable material near a well-used pedestrian access, so most were cut into lengths about 50cm.

Near the few native trees on CHF Bank, on the near edge of Flame Tree Bank, Alocasia brisbanensis (Elephant's Ear) was cut at its many bases.

Honeysuckle and blackberry remnants were uprooted or cut at base where uprooting was not possible due to dry ground or deep rooting among native tree roots or harakeke. Semi-rotting of the roots of some blackberry and honeysuckle was achieved between visits by partially breaking or damaging stems near the base, then trampling to covering the roots with live growth, adding weed material from nearby to create a moist environment within the pile. This allowed many honeysuckle and blackberry plants to be uprooted a month or two after the initial intervention.

The stems of Calystegia - probably the same invasive/native cross as that throughout the Upper Forest margins, ie C. silvatica x sepium subsp roseatum - were cut or broken as encountered, occasionally removing some of the root.

On the CHF Bank canopy margin, the single Chinese privet on the canopy margin, and the single cotoneaster in the canopy, were ringbarked again.

Two small Flame trees were ringbarked with apparent initial effect on one, but no lasting effect on either observed by January 2019.

In the manuka/kanukacanopy throughout Gahnia Grove:

A single c. 3mH hakea was uprooted fairly easily as it was already semi-fallen, perhaps due to an earlier weed-control intervention.Remaining Pampas, previously suppressed and weakened by trampling, was uprooted

Bulbil Watsonia and Aristea ecklonii (Blue corn-lily) were suppressed by pulling, cutting or mulching near the canopy margin at the edge of the large grassed area, or "Glade".

Native trees and shrubs released by the contractor's work with volunteer follow-up:

• on Cape Honey Flower Bank:

Mahoe (the only one present in Gahnia Grove)
Three mature ti kouka and several juveniles
Several karamu to c.4mH, some defoliated and seriously weakened by almost complete honeysuckle coverage, and several juveniles
Two large mapou and several juveniles
A large isolated harakeke half-way down the bank
3 kawakawa juveniles c. 1mH

• on the kikuyu margin under the Flame Tree:

A honeysuckle-covered hebe
Two honeysuckle-covered karamu
Two houhere

For the Volunteer follow-up to Paul's work, see "Weed control - Winter-Spring summary"
https://inaturalist.nz/projects/gahnia-grove-site-summary-and-discussion/journal/20963-weed-control-winter-spring-summary

Posted on January 22, 2019 01:52 AM by kaipatiki_naturewatch