Botanical assessment of Francella Reserve CCCECO 04/15 13 August 2004

K McCombs Table of Contents Introduction ..................................................................................................................................................................................................... 1 Site .................................................................................................................................................................................................................. 1 Vegetation Description ................................................................................................................................................................................... 2 Discussion ....................................................................................................................................................................................................... 5

Restoration of wetland ............................................................................................................................................................................... 5 Areas of fill ................................................................................................................................................................................................ 5 Hydrology of the site ................................................................................................................................................................................. 5 Weed control ............................................................................................................................................................................................. 5

Conclusion ...................................................................................................................................................................................................... 5 Acknowledgements ......................................................................................................................................................................................... 6 References ....................................................................................................................................................................................................... 6

Appendix 1. Weed control methods .......................................................................................................................................................... 7 Appendix 2. Plant species list for Francella Reserve (July 2004) ............................................................................................................. 8 Appendix 3. Plant species list for Bromley Marsh (September 1997, February 2000) ............................................................................. 9

Introduction Accompanying the development of an industrial subdivision in the vicinity, a landscape design is being drawn for Francella reserve. A botanical assessment of the site was requested, and a site visit was made on 28/7/04, with Tony Milne from Peter Rough Landscape Architects Ltd.

Site The reserve is a small part of what was formerly identified as Bromley Marsh (see Figure 1). The site is an old dune remnant with a mixture of sandy and peaty soils that includes low-lying areas. Prior to the industrial developments the site was grazed by horses. Major earthworks have occurred around the reserve, and these have altered the site’s hydrology. Earthworks have also been carried out on the site itself and a significant portion of the reserve has been filled. There are several ponds present. The main pond has a waterway entering it from the north, and the water leaves via a boxed drain to the south, along the eastern margin. To the north of the pond is an area of quaking bog.

Figure 1. Location of Francella Reserve (solid black outline) and the former more extensive Bromley Marsh (dashed black outline).

Additional buildings, roads etc. have been formed since the aerial photograph was taken.

Vegetation Description A list of the plant species observed on this most recent assessment is included as Appendix 2. The margins of the reserve are mainly dominated by weeds, including shrub weeds such as *1gorse, *broom and *blackberry. The northern boundary also has bracken, *elder and poroporo. The eastern boundary has trees of *crack willow and *grey willow.

Figure 2. Dense area of *lupin, *blackberry and bracken at northern end.

The relatively flat raised areas, mainly to the south and west, are a mixture of weedy species and grasses.

Figure 3. Filled area at the southern end (looking ~south-east).

1 Exotic species are indicated with an asterix.

Figure 4. The interface between the pond and one of the filled areas, which is dominated by weeds (looking ~south-east).

There is a small amount of land that is higher than the ponds, but that has not been filled. There is still some remnant short turf vegetation on these parts, including arrow grass (Triglochin striata).

Figure 5. Short turf area to the south of the pond (looking ~north).

The wet areas to the north of the ponds, on the quaking bog, have freshwater sedges, rushes and grasses. The pond is currently dominated by weedy aquatic riparian species such as *jointed rush and *creeping buttercup. There was also quite a lot of algae present. It is likely that other species would appear in summer when it has dried out to some extent.

Figure 6. Main pond.

Discussion

Restoration of wetland A botanical survey of the Bromley Marsh area was carried out in September 1997 (Meurk 1997) and the site was also assessed in February 2000 (McCombs 2000). The species recorded on these occasions are listed in Appendix 3. Several locally rare species were recorded on these previous occasions, including centella (Centella uniflora), small spike sedge (Eleocharis gracilis), silverweed (Potentilla anserinoides) and NZ buttercup (Ranunculus glabrifolius). None of the locally rare species were found on this recent visit, although admittedly it was not the ideal time of year to see some of the smaller and/or annual species. Nevertheless all of the areas that have been filled have undoubtedly lost their wetland vegetation. Several of the species were locally rare, so this is a significant loss to Christchurch’s biodiversity. The earthworks in and around the site have had a significant impact on the site’s botanical values, and its potential. One possible remedy would be to remove most of the fill, to restore the wetland that has been lost, even though it will still be much smaller than originally. Much of the fill shown in Figure 3 could be removed down to the level of the ground shown in Figure 5. However maintenance of short-turf vegetation, in the absence of grazing, would be difficult to achieve. The most significant species formerly recorded were not within the reserved area (Meurk, pers.comm.), so it is probably not worth pursuing that at this stage. Planting along the waterways and ponds would increase the site’s ecological value. Species listed in the Streamside Planting Guide (CCC, 1998) would be appropriate.

Areas of fill Any planting on areas of fill will need to take into account the nature of the fill. Formerly the site was sandy, so coastal forest species would probably be appropriate (see McCombs, 1992).

Hydrology of the site Another change which might raise the botanical values of the site would be to improve the flow through the pond, which appeared relatively stagnant. Associated planting could also be carried out. Another option would be to re-route some of the water flows within the reserve so that the area to the north is not quite so wet. The northern area is now quaking bog, so it is presumably receiving much more water than previously.

Weed control The reserve has quite a few weeds that need control. Ideally this should be combined with restoration planting. Quite a few would also be controlled if the area of fill was significantly reduced, as discussed above. The following species should be specifically targeted for control: • *gorse and *broom (required by the Regional Pest Management Strategy, ECan) • female *grey willow (control of female plants will limit the dispersal of this species) • *blackberry • *crack willow • *tree lupin Suggested control methods are outlined in Appendix 1.

Conclusion The previous botanical value of the site was mainly in the short-turf wetland vegetation. Most of this is now either drowned, filled, or being invaded by exotic grasses in the absence of grazing. Restoration planting of wetland species would increase the site’s ecological value, although it will

not mitigate the loss of several locally rare species that were formerly present in the larger marsh area. Weed management at the site will also be an ongoing issue, so control measures and priorities are provided.

Acknowledgements Thanks to Colin Meurk for discussion about the restoration possibilities at this site, and to Tony Milne for supplying all of the on-site photographs in this report.

References Craw J (2000) Weed Manager. A guide to the identification, impacts and management of

conservation weeds of New Zealand. Department of Conservation Canterbury Regional Council (1998) Regional Pest Management Strategy (1998). Canterbury

Regional Council Christchurch City Council (1998) Streamside Planting Guide. What to plant and how to maintain

native plants along freshwater streams in Christchurch. Pamphlet available from the Christchurch City Council, also available at www.ccc.govt.nz/streamside/

McCombs K (1992) Foreshore vegetation from Waimakariri River to Taylors Mistake. Christchurch City Council

McCombs K (2000) Bromley Marsh. Christchurch City Council Meurk C (1997) A previously unreported grazing marsh in Bromley. Christchurch City Council.

Appendix 1. Weed control methods These are based on: Craw J (2000) Weed Manager. A guide to the identification, impacts and management of conservation weeds of New Zealand. Department of Conservation

blackberry (Rubus fruticosus agg.) • Dig out small patches, any time of year • or, apply Escort at label rates, summer-autumn (before leaves become brittle)

broom (Cytisus scoparius) • Dig out small plants, any time of year • or, cut and paint with Grazon or Escort or Stump Stick at label rates, any time of year

crack willow (Salix fragilis) • 1 cut / 100 mm diameter, squirt with 10 ml glyphosate, summer-autumn Where practical, poison and leave standing - otherwise it is difficult to dispose of, and any live cut material will re-grow if left on the ground.

gorse (Ulex europaeus) • Cut and paint with Grazon at 10% any time of year • or, cut and paint with Escort 2 g/L any time of year

grey willow (Salix cinerea) Mark female plants at time of flowering (Sep-Oct). Eradicate female plants first to reduce seed production and therefore spread of this species. Do not cut and leave lying around - pieces will re-grow. Use one of the following methods on larger trees, and if possible, leave standing until dead: • Cut and squirt with 1 cut / 100 mm diameter, 10 ml glyphosate, summer-autumn • or, bore and fill with 1 hole / 100 mm diameter, 10 ml glyphosate, summer-autumn • or, frill using glyphosate 10%, summer-autumn For small plants or seedlings that are not in water cut with Vigilant tipit gel pruner and remove material to landfill.

tree lupin (Lupinus arboreus) • Hand pull or dig out small plants, any time of year • or, cut and paint with glyphosate 20%, ay time of year • or, apply Grazon at label rates, when plants are actively growing

Appendix 2. Plant species list for Francella Reserve (July 2004) * Indicates the species that are not native to New SPECIES COMMON NAME Algae f.g.a filamentous green algae Ferns & Allies Pteridium esculentum bracken Grasses *Agrostis stolonifera creeping bent *Bromus wildenowii prairie grass *Elytrigia repens couch *Festuca arundinacea tall fescue *Holcus lanatus Yorkshire fog *Lolium perenne ryegrass Herbs (Dicot) *Brassica sp. brassica *Conium maculatum hemlock Cotula coronopifolia batchelors button *Cotula sp *Fumaria officinalis fumitory *Gnaphalium sp. cudweed Lemna minor duck weed *Leontodon taraxacoides hawkbit *Lepidium sp. pepper cress *Lotus sp. lotus *Lupinus arboreus tree lupin *Malva sp. mallow *Matricaria inodora scentless mayweed *Mimulus guttatus monkey musk *Myosotis laxa subsp. caespitosa water forget-me-not *Plantago lanceolata narrow plantain *Ranunculus repens creeping buttercup *Rorippa microphylla water cress *Rumex obtusifolius broad dock Senecio minimus fireweed, NZ groundsel *Spergularia sp. spurrey Rushes/Sedges Eleocharis acuta sharp spike sedge *Juncus articulatus jointed rush *Juncus effusus soft rush Juncus planifolius wi Juncus ?pallidus wi, giant rush Triglochin striatum arrow grass Trees/Shrubs *Alnus glutinosa alder *Chamaecytisus palmensis tree lucerne Coprosma repens taupata *Cytisus scoparius broom *Salix cinerea grey willow *Salix fragilis crack willow *Sambucus nigra elder Solanum laciniatum poroporo *Ulex europaeus gorse Vines/Climbers *Rubus fruticosus agg. blackberry

Figure 7. Juncus pallidus.

Appendix 3. Plant species list for Bromley Marsh (September 1997, February 2000) * Indicates the species that are not native to New SPECIES COMMON NAME

Ferns & Allies Blechnum minus swamp kiokio *Dryopteris filix-mas male fern Pteridium esculentum bracken Grasses *Agrostis stolonifera creeping bent *Bromus diandrus ripgut brome *Bromus tectorum downy brome *Bromus wildenowii prairie grass *Festuca rubra chewings fescue *Holcus lanatus Yorkshire fog *Lolium perenne ryegrass Herbs (Dicot) *Callitriche stagnalis starwort Centella uniflora centella *Cerastium fontanum mouse-ear chickweed *Chenopodium album fathen *Cirsium arvense Californian thistle *Cirsium vulgare scotch thistle *Conium maculatum hemlock Cotula coronopifolia batchelors button *Crepis capillaris hawksbeard Epilobium billardiereanum willowherb *Galium palustre marsh bedstraw *Geranium molle dove's-foot cranesbill Hydrocotyle novae-zeelandiae NZ pennywort *Hypochoeris radicata catsear *Leontodon taraxacoides hawkbit *Lepidium bonariense Argentine cress *Lepidium sp. pepper cress *Lupinus arboreus tree lupin *Myosotis laxa subsp. caespitosa water forget-me-not Myriophyllum propinquum water milfoil *Orobanche minor broomrape *Parentucellia viscosa tarweed *Picris echioides oxtongue *Plantago lanceolata narrow plantain *Plantago major broad plantain Potentilla anserinoides silverweed *Prunella vulgaris selfheal Ranunculus glabrifolius buttercup *Ranunculus repens creeping buttercup *Ranunculus sceleratus celery leaved buttercup *Rorippa nasturtium-aquaticum watercress *Rumex acetosella sheep sorrel *Rumex conglomeratus clustered dock *Rumex obtusifolius broad dock *Sagina procumbens pearlwort Senecio glomeratus NZ groundsel Senecio minimus fireweed, NZ groundsel *Silene latifolia white campion *Sisymbrium officinale hedge mustard *Spergularia sp. spurrey *Trifolium fragiferum strawberry clover *Trifolium glomeratum clustered clover *Trifolium repens white clover *Tripleurospermum inodorum scentless mayweed *Veronica sp. speedwell

Mosses Moss spp.

Orchids Microtis unifolia onion orchid Rushes/Sedges *Carex flacca blue sedge Eleocharis acuta sharp spike sedge Eleocharis gracilis slender spike sedge *Isolepis setacea sedge *Juncus articulatus jointed rush *Juncus effusus soft rush Juncus pallidus wi, giant rush Juncus planifolius wi Triglochin striatum arrow grass Trees/Shrubs *Alnus glutinosa alder *Cytisus scoparius broom *Salix cinerea grey willow *Salix fragilis crack willow *Sambucus nigra elder Solanum laciniatum poroporo *Ulex europaeus gorse Vines/Climbers *Galium aparine cleavers *Rubus fruticosus agg. Blackberry

Figure 8. Silverweed (Potentilla anserinoides).