Final report on 2019/20 Trial of Site-based non-chemical weed control for ecological restoration
Many findings have already been reported, some in more detail, in earlier photo observations and/or text reports. Here we try to summarise our experience of the application of this methodology to a site during a single year of integrated ongoing survey, planning and intervention.
Some locations are named, eg Zone Ca, or ZoneCaKSS. Links to all the Trial Zones and locations, or “sub-zones”, are provided here.</a href>
This trial aimed to
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demonstrate the effectiveness of manual weed control over time
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help establish optimal rates of weed reduction for gradual replacement of invasive plants with native wild vegetation.
NB Maximum effectiveness means maximum growth, density and diversity of native vegetation. Weeds are removed because they are inhibiting existing or potential native habitat.
So effective weed control requires assessment of the likely or potential development of native habitat, the needs of existing or potential species in that habitat, and the minimisation of soil moisture loss, habitat disturbance, erosion, soil contamination and water pollution.
- Assess changes since the fulltime volunteer restoration project of 1997-99, especially observable results of both intervention and non-intervention
Unless otherwise noted Observations below are limited to the defined Trial area, ie the banks below Kaipatiki Roadside, down to the stream and up the opposite bank to the forest path (“Native Plant Trail”).
- Ongoing survey
The methodology’s attention to species identification throughout the trial helped preserve, at least temporarily, some existing native plants and invertebrates, and facilitated the beginnings of regeneration in some areas impacted both historically and recently by Reserve users, along the roadside, on the banks below, and along the forest path.
1:1 Plant identification
Of special interest among species identified during the Trial were some natives often either damaged accidentally, treated as weeds due to their common occurrence in cultivated land, or misidentified as exotics they closely resemble.
Following standard practice, no plant was damaged unless it had been identified as exotic. Photographs were taken, sometimes many times until diagnostic features were successfully captured in the images uploaded to iNaturalist for discussion and species ID or confirmation by experts, particularly of ferns. Visitors made some identifications of large trees. No plant material needed to be collected for ID purposes, though some known exotics, eg a fan palm seedling and an invasive grass, were collected for closer study and photography.
With this invaluable help, we learned to recognise some species new to us, eg:
• the invasive fern Cretan brake (Pteris cretica), which was removed from several streambank locations, releasing native Blechna and Deparia
• the native Dark nightshade (Solanum opacum), found both beside the path and on sun-exposed edges of the streambank, sometimes among groups of the very similar Black nightshade (S. nigrum), which is itself a benign exotic that provides ground cover, shade that nurses native seedlings, and fruit observed being eaten by birds
• several invasive palms, after discovering the banks of the Kaipatiki Stream now hold several mature Bangalow and a Chusan, numerous Phoenix and Bangalow seedlings, and an unidentified species of Fan palm seedling.
• Calystegia sepium, x silvatica, a hybrid of the native Hedge bindweed (Calystegia sepium subsp roseata) with the invasive exotic Calystegia silvatica, ie the locally common weed often referred as convulvulus. This bindweed overtook about 20m of the 1998 roadside planting of kanuka and is still common here, though less abundant in the now-canopied areas of roadside, and possibly not harming the present vegetation.
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