Botanist Newsletter
Issue No. 32, June 2001 to February 2002
Contents
Weed Workshop
A combined weed workshop was held in February, with Environment Canterbury, Department of Conservation, City Care and City Council staff. Live material for about 50 weeds was available, along with species that look similar, for comparison. The weed species covered included some that are not currently known from the region, since early detection greatly increases the chance of effective eradication.
The morning included a brief site visit to Cockayne Reserve, to discuss some of the practicalities of weed control on a real site. The new legislation relating to unwanted organisms was explained. DoCs ‘weed-led’ and ‘site-led’ approach was also discussed.
An accompanying field guide (“Canterbury Weed Guide”) was produced using material from DoCs “Weed Manager”, pamphlets from ECan, material from the “Christchurch Waterway Maintenance Plant Guide” and some additional material produced by DoC and CCC staff. The intention is that the material will be further added to and refined over time.
Ongoing co-operation between all three organizations, on various weed-related projects, is occurring.
Several very worthwhile workshops were recently arranged by the Department of Conservation on “Problem Aquatic Weeds”. The workshops were held at Travis Wetland and attended by staff from several organisations.
Purple Loosestrife
The extent of purple loosestrife infestation in the city is currently being researched. We are endeavouring to achieve a greater level of control of this species.
Purple loosestrife is a highly invasive species that has recently been declared an unwanted organism in New Zealand. It is among the most invasive species in the world - a list which does not only cover plants[1].
The City Council is targeting control effort along the Avon River and in Cockayne Reserve. Some private landowners are also being approached and removal of plants on their land being offered. The ability of this plant to produce huge numbers of seeds make it well worth controlling as many seed sources as possible.
A fact sheet is available from Helen Braithwaite at the Department of Conservation to assist in identification and to encourage reporting of this species (HBraithwaite@doc.govt.nz).
Figure 1. Purple loosestrife (Lythrum salicaria).
Egeria
Several applications of diquat were made in 2001, to control egeria in the Kerrs Reach of the Avon River. Monitoring by NIWA found that diquat effectively controlled egeria and Canadian pondweed, but only had an effect on the potamogetons directly where the diquat was applied.
Water analysis showed that the diquat dispersed quite quickly, although levels did increase again briefly on the incoming tide. Results from monitoring of invertebrates and eels also showed no adverse effects.
Following the publicity to explain what the councils was doing and why, public reaction has generally been positive. The main issues have been the use of herbicide, and restricting river use for 24 hours. Recreational users were also effected by the council not harvesting, but this was a one off occurrence for the period of the initial trial.
Figure 2. NIWA diver recording the location of egeria plants.
The council has concluded that diquat is a practical tool for controlling egeria, with some limitations.
The CCC plans to:
- Pursue a high level of control, to minimise spread
- Carry out regular species surveys
- Continue to use limited quantities of diquat, but to refine the techniques, to minimise the amount used
- Continue harvesting of aquatic weed with a strict sanitising regime to minimise the chance of further spread of this weed
- Continue with publicity and education; especially to encourage the public to thoroughly clean any equipment that has been in the river
The weed harvester is now thoroughly inspected each time it is shifted between catchments. All fragments are removed, the entire machine is steam cleaned, dried, then sprayed with Roundup. An independent inspection is also carried out and if not acceptable, the process is repeated.
Unfortunately egeria has recently been found at several additional sites in Christchurch. These sites were found by Department of Conservation staff carrying out a nationwide survey for pest fish.
Figure 3. One of the ponds where egeria has recently been found.
City Plan References
Botanical evidence has been researched and prepared for six different cases that are going to the Environment Court, regarding various aspects of the City Plan. Negotiations mean that at least some of these may be resolved before actually reaching the court.
Draft Grazing Strategy
The draft strategy “Grazing Management of CCC Reserves on the Port Hills” has been completed and circulated for comment. A number of responses have resulted and these will be considered over the next month to determine what to do next.
Resource Consents
Botanical data and management advice has been provided for a number of sites where Resource Consents have been sought including Bexley Wetland, Charlesworth Wetland, Chaneys Forest and Brooklands Lagoon.
Ecological Heritage Sites
Ongoing monitoring of Ecological Heritage Sites has included site visits to:
- Horseshoe Lake (EHS 13.01) This site is very mixed in composition. In many parts there is an exotic canopy of willow and some alder. Beneath this karamu (Coprosma robusta) is dominant, then swamp kiokio (Blechnum minus) with patches of ferns such as male fern (Dryopteris filix-mas) and pig fern (Hypolepis ambigua). Cabbage trees (Cordyline australis) form the dominant sub-canopy in some parts. Duckweed (Lemna minor) is abundant on open water in the drains.
- Brooklands Lagoon (EHS 5.01) There are some large areas of bracken regenerating on some of the dunes on the landward side of the lagoon. Large stands of bracken are now hard to find on the plains (J. Wilmshurst, pers. com.) Also of note was the locally uncommon species silverweed (Potentilla anserinoides).
- Mt Vernon Valley (EHS 24.01)
- Avoca Valley (EHS 25.01) This site is particularly notable for the amount of leafless clematis (Clematis afoliata) on the bluffs. There is also a stream restoration project occurring at the bottom of the valley.
- Horotane Valley (EHS 26.01) One of the largest populations of korokio (Corokia cotoneaster) on the Port Hills occurs at this site.
- Barnett Valley, true left (EHS 29.01) The top part of this site was assessed with regard to an appeal against the proposed zoning in the city plan.
- Central Barnett Valley top bush (EHS 29.04) Possible funding is being investigated, to enable this remnant forest site to be fenced off from grazing.
- Groynes (EHS 3.13) The insectivorous bladderwort (Utricularia dichotoma) was flowering in mid-November. There are a number of locally rare species at this site.
- McLeans Reserve (EHS 1.33) Of particular note was an impressive number of onion orchids (Microtis unifolia) present and flowering (in November). There is also a significant patch of pohuehue (Muehlenbeckia ephedroides). This species is categorized as “naturally uncommon (sparse)[2]”. This category means that the species is known to occur naturally only within small and widely scattered populations. Although this is how the populations occur naturally, as a result they are vulnerable to loss in parts of their range.
- McLeans Island Rd stopbank (EHS 1.31). This site has the locally rare grass sand twitch (Zoysia minima). In December the site was formally surveyed.
Figure 4. Leafless clematis (Clematis afoliata) in Avoca Valley.
Figure 5. Bladderwort (Utricularia dichotoma) at the Groynes.
Figure 6. Pohuehue (Muehlenbeckia ephedroides).
Plant Photos
A recent purchase by the Parks and Waterways Unit of a high resolution digital camera will facilitate high resolution digital photographs, including close ups. Good quality photographs are invaluable for plant identification, education and promotion of natural areas.
Recent requests for plant photos have included the following projects:
- Various rangers talks, e.g. to a local climbing group.
- Wetland plant photographs to be used in information panels being put together by Department of Conservation for the Otipua (Timaru) Wetland Charitable Trust.
- Department of Conservation poster of rare species, which includes swamp nettle (Urtica linaarifolia).
- To produce resource materials by the city councils environmental education officers.
- For an article in the Star about the floating fern retoreto (Azolla rubra).
- Several misc. requests received by email (Pittosporum tenuifolium, Urtica ferox).
Figure 7. Swamp nettle (Urtica linaarifolia).
Figure 8. The floating fern retoreto (Azolla rubra).
McLeans Grasslands
A folder of photographs and information on McLeans Grasslands has been produced. Initially this was compiled for councilors who were going on a site visit to the area, but it has proved useful for talking to a range of people about the area. The folder includes both plant and animal information and photographs.
Figure 9. Skink - an inhabitant of the McLeans grasslands.
Figure 10. Copper butterfly - another inhabitant of the McLeans grasslands.
Figure 11. Mosses, lichens and grasses in the McLeans grasslands.
Mistletoe
A significant population of small-flowered mistletoe (Ileostylus micranthus) was found as part of an assessment for a resource consent application on the Port Hills. Many of the plants are on tree lucerne.
The mistletoe is classified as “vulnerable” in the threatened plant list[3]. This category is for species that are:
‘…numerically abundant, but which are either under threat from serious adverse factors throughout their range, or occur as widely scattered, typically small populations, many of which are undergoing declines through loss of reproductive ability, recruitment failure, predation, or through other processes of often subtle habitat change. Declining taxa are listed to highlight their plight, for without some level of management they are destined to become the future threatened plants of New Zealand’ (p. 614)
Small-flowered mistletoe is especially uncommon in the North Island, where it suffers principally from possum browsing (N. Head, per. comm.).
Figure 12. Mistletoe on the Port Hills (Ileostylus micranthus).
Reports
Recent reports produced include:
- Botanical assessment of van Asch property, where re-zoning has been proposed (Appeal 197). CCCECO 01/07.
- Botanical assessment of part of McLeans Reserve (west of Conservators Rd) with regard to using it for hay. CCCECO 01/8.
- Botanical assessment for part of Moncks Spur. CCCECO 01/09.
- Horse grazing on part of Seafield Park. CCCECO 01/10.
- Notes on management for dry plains grasslands in relation to grazing leases. CCCECO 01/11
Books in Library
Recent books and reports purchased and available to borrow include:
- Bellingham P (2001) Evaluating methods for the protected natural areas programme. Science & Research Internal Report 190. Department of Conservation
- Collier KJ, Winterbourn MJ (Eds.) (2000) New Zealand Stream Invertebrates – Ecology and Implications for Management. New Zealand Limnological Society. Caxton Press, Christchurch.
- Forgie V, Horsley P, Johnson J (2001) Facilitating community-based conservation initiatives. Science for Conservation 169. Department of Conservation.
- Harris S, Brown J, Timmins S (2001) Weed surveillance - how often to search? Science for Conservation 175. Department of Conservation
- Overton JM, Leathwick JR (2001) Measuring environmental distinctiveness. Science for Conservation 174. Department of Conservation
- Patrick B (2000) Lepidoptera of small-leaved divaricating Olearia in New Zealand and their conservation. Science for Conservation 168. Department of Conservation
- Suckling DM, Stevens PS (2000) Managing Urban Weeds and Pests. Proceedings of a New Zealand Plant Protection Society Symposium 1999. New Zealand Plant Protection Society.
- Webb C, Johnson P, Sykes B (1990) Flowering Plants of New Zealand. DSIR Botany.
Bird Maps
The attached maps of bellbird and kereru sightings are a compilation of about a decades informal observation by the public. We hope to publish such records periodically to see how the situation is changing. Any additional observations would be welcome.
For any further feedback on native bird sightings please send to colin.meurk@ccc.govt.nz with the following information - address, location or grid reference, date observed, number seen, behaviour (especially feeding or breeding - and what plants being used).
There is also a detailed bird-banding study of bellbirds being carried out by Landcare Research with assistance from Scott Butcher (Lincoln University), CCC, Ornithological Society, and Barbara Anglem (Canterbury University). If you see any banded birds or want to participate in the study there are calendars for recording these observations available from Kate McCombs' desk. You need binoculars to observe the colours and sequences of the bands and what legs they are on.
Location of Bellbird Sitings in Christchurch (download PDF)
Location of Kereru Sitings in Christchurch (download PDF)
References
- 100 of the world’s worst invasive alien species. A selection from the global invasive species database. Published by ISSG, the Invasive Species Specialist Group of the Species Survival Commission (SSC) of The World Conservation Union (IUCN). http://www.iucn.org/biodiversityday/booklettext.doc
- de Lange PJ, Heenan PB, Given DR, Norton DA, Ogle CC, Johnson PN, Cameron EK (1999) Threatened and uncommon plants of New Zealand. New Zealand Journal of Botany 37: 603-628
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