Japanese honeysuckle control in Gahnia Grove June 2018-19

PRE-INTERVENTION:
https://inaturalist.nz/observations?order=asc&order_by=observed_on&place_id=any&subview=grid&verifiable=any&field:Japanese%20honeysuckle%20control%20in%20Gahnia%20Grove=pre-intervention

DURING CONTROL:
https://inaturalist.nz/observations?order=asc&order_by=observed_on&place_id=any&subview=grid&verifiable=any&field:Japanese%20honeysuckle%20control%20in%20Gahnia%20Grove=during%20control

YEAR ONE SIDE-BY-SIDE some views showing honeysuckle control:

Lower Arena smv3:
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=smv3

Lower Arena smv4:
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=smv4

Glenfield Roadside under Flame Tree, smv16:
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=smv16

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

Below is a list of 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)
https://inaturalist.nz/observations?d2=2019-06-22&order=asc&order_by=observed_on&place_id=any&project_id=gahnia-grove-umbrella-project&subview=grid&taxon_id=77835&verifiable=any

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 hoenysuckle 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:https://inaturalist.nz/observations/13034933

First it was cut from the few trees on Flame Tree Bank
-https://inaturalist.nz/observations/18501728
leaving Tradescantia and Calystegia with increased dominance as ground cover:
-https://inaturalist.nz/observations/18444670

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:

https://inaturalist.nz/observations?order=asc&order_by=observed_on&place_id=any&subview=grid&verifiable=any&field:Japanese%20honeysuckle%20control%20in%20Gahnia%20Grove=logroll%20formed%20and%20suppressing%20growth

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:

https://inaturalist.nz/observations?order=asc&order_by=observed_on&place_id=any&subview=grid&verifiable=any&field:Japanese%20honeysuckle%20control%20in%20Gahnia%20Grove=dried%20or%20rotted%20log-roll%20being%20successively%20moved%20back%20and%20roots%20beneath%20uplifted

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:

https://inaturalist.nz/observations?order=asc&order_by=observed_on&place_id=any&subview=grid&verifiable=any&field:Japanese%20honeysuckle%20control%20in%20Gahnia%20Grove=after%20rotting%20and%20removal%20of%20log-roll%20and%20uplifting%20of%20roots%20beneath

KNOTTING cut stems:
A method of suppression where roots cannot be accessed and burial under mulch is not possible:
https://inaturalist.nz/observations/14728422

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:
https://inaturalist.nz/observations?order=asc&order_by=observed_on&place_id=any&subview=grid&verifiable=any&field:Japanese%20honeysuckle%20control%20in%20Gahnia%20Grove=new%20growth%20on%20stems%20completely%20severed%20from%20any%20root%20connection

REGROWTH FROM CUT STEMS NOT SUPPRESSED BY MULCH
-https://inaturalist.nz/observations?order=asc&order_by=observed_on&place_id=any&subview=grid&verifiable=any&field:Japanese%20honeysuckle%20control%20in%20Gahnia%20Grove=regrowth%20from%20unmulched%20cut%20roots

Posted by kaipatiki_naturewatch kaipatiki_naturewatch, July 04, 2019 05:09

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