Weed control - Spring summary
For ongoing kikuyu control on the mown margin, see https://inaturalist.nz/projects/gahnia-grove-site-summary-and-discussion/journal/20558-mown-kikuyu-border-evolving-a-long-term-strategy-for-current-trial
Major weed removal on Cape Honey Flower (CHF) Bank by a contractor is covered here:
https://inaturalist.nz/projects/gahnia-grove-site-summary-and-discussion/journal/20965-contractor-assistance-missions-accomplished
Volunteer followup on CHF Bank was possible, as no significant signs of slippage were uncovered, and there was no culvert on CHF. The contours and vegetation do suggest a culvert hidden under the Tradescantia on Flame Tree Bank, so we are weeding our way only cautiously in that direction.
On CHF Bank, a large volume of cut CHF wood was laid straight as compactly as possible, and covered with green weed material to assist rotting. The entire CHF plant is extremely toxic, having produced fatalities in both humans and animals, so CHF was moved away from the more accessible areas of the site used by dog-walkers. The hollow stems provide excellent invertebrate habitat, with several ant nests observed. Disturbance of this habitat will be minimised.
Regrowth of CHF and Alocasia is being allowed as shade and habitat around released trees until exotic herbs cover CHF bank. (Exotic herb cover of CHF Bank began in the previously-sprayed kikuyu margin after kikuyu pullback beginning in June 2018, and progressed down the bank after major shrub/vine weed removal in October 2018. Purpletop [Verbena bonariensis] is most abundant.
Other than those areas mentioned above, not a lot of actual weeding has been required. Site work at GG has mainly been of improving access (for current and future weeding) , improving the appearance of the outer margin, and fire hazard prevention. All these aims were met mainly by compacting, piling and suitable disposition of dry woody materials.
There has been no major eruption of weeds other than the expected such as Calystegia, simply being pulled off as it is observed (monitoring has been at least fortnightly, but in practice often several times a week, meaning the Calystegia has not had time to gather much nourishment . If frequent control is continued, perhaps the seasonal growth will not be as rampant next year - to be discovered in due course)
While perusing the exotic herbiage we have plucked out hundreds of Yorkshire fog seedlings while they were small and the ground not yet too dry. Occasionally we have thinned a group of exotic herbs dense enough to suppress native seedlings. In general we have not yet considered it beneficial to remove any annual exotic herbs, as they are providing mini-canopy, moisture retention and erosion control, and suppressing more difficult-to-manage weeds.
In areas without benign exotics, new occurrences of aggressive exotic herb seedlings such as docks and Creeping buttercup continue to be reduced or mulched as convenient.
Tree/shrub weeds
The single mature Chinese privet continued to flower vigorously and then fruit despite through ring-barking of all major branches and trunk bases. Its major branches provided the only canopy at the bottom of the Arena/CHF bank margin, bare after release from honeysuckle, blackberry and Cape Honey Flower. Those branches were also poised to provided many privet seedlings, while the abundant berries on the newly-leafing branches of surviving karamu offer birds food nearby, so reluctantly we sawed far enough through the privet's major branches to allow the weight to pull them to the ground, where we can more easily monitor and control fruit and seedling development.
The Chinese privet, latest intervention: https://inaturalist.nz/observations/19586404
Other tree/shrub weed remnants have required little time, with new growth being briskly leaf-stripped and/or bent/broken, and adjacent natives growing into the released space.
Moth plant seedlings are germinating by the dozen on the lower part of CHF bank, partiularly the canopy margin, where a mature vine was found and removed in Oct 18 and tradescantia was removed in winter. These seedlings are being uprooted where possible but we have seen that they often break off, even when small, and that even the tiniest seedling will regrow from a leafless broken ste. Therefore we are also mulching areas of Moth plant seedling germination with mini-piles of the adjacentTradescantia, both to reduce ongoing germination and to improve soil conditions for future uprooting. we will be interested to see how many Moth plants germinate in the Tradescantia, and to what depth mulched seedlings survive.
Brush wattle seedlings are as numerous as ever, esp. in the lower Arena and adjacent canopy margin, some now reaching c. 30cm hidden mong the wildcarrots and oxtongues, but all easily removed when spotted. Even if a few reach a metre, their stems are easily broken or cut and are not believed to reshoot or sucker.
All other weed management continues much as reported in previous months, with good results: ie diminishing weed numbers found, weeds turning to humus, regrowth and reproduction within expected limits.
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