AUCKLAND COUNCIL
WEONA COASTAL WALKWAY
VEGETATION ASSESSMENT OF THE
COASTAL TRACK SECTION.
Auckland Council
Weona Coastal Walkway
Vegetation Assessment of the
Coastal Track Section.
SEPTEMBER 2012
FOR : AUCKLAND COUNCIL
BY :
BIORESEARCHES GROUP LTD
Graham Don, M.Sc Hons
Rhys Gardner, Ph.D
CONTENTS
Page No.
1
INTRODUCTION ........................................................................................................ 1
2
VEGETATION AND FLORA .................................................................................... 4
3
CONCLUSIONS AND RECOMMENDATIONS ..................................................... 6
1
1
INTRODUCTION
It is proposed to form a walkway around the Westmere coast on the eastern side of the
Motions Creek inlet, from Lemington Reserve to Weona Reserve and on to Garnet Road. Its
easternmost c. 250 m, from Lemington Reserve to a point of relatively high ground below the
eastern arm of Sunnybrae Crescent (Nos 24/26), passes through coastal scrub that lies
between the residential properties and a mangrove-filled inlet.
This report only describes the vegetation along the easternmost c. 250 m of Stage III of the
walkway. The assessment was undertaken in order to determine whether formation of a
walkway might have any adverse botanical effects.
The City of Auckland – District Plan Isthmus Section – Operative 1999 lists the
“Weona/Lemington Coastal Edge Forest” as a Significant Ecological Area (SEA) in its
Appendix C. The areas contributing to the SEA are as follows from the Plan –
ADDRESS
LEGAL DESCRIPTION
CATEGORY
MAP
REF.
Weona / Lemington Coastal Edge Forest
40a Lemington Road (Lemington Reserve)
Lot 103 DP 20641; Pt Allot 10 Sec 9
Suburbs of Auckland; Lot 4 DP 48055
A
C05-22
Adj 60a Sunny Brae Crescent
Accessway to Lot 4 DP 48055
A
C05-22
36 Westmere Park Avenue (Westmere Park)
Lot 1 DP 20641
A
C05-22
A review of Council information on this area was undertaken but there was no explanation of
the reason for its registration as an SEA.
As a precaution a botanical survey was
recommended by the Feasibility Assessment report (Bioresearches, September 2012)a to
determine whether any significant species or plant communities would be affected.
The proposed route more or less follows an existing unformed foot-track. Most of it is
situated a short way above the high tide level but rises to c. 10 m above sea level at the point
below Sunnybrae Crescent (which is where the inlet up to Lemington Road reaches the main
part of the Motions Creek estuary).
[a Bioresearches, September 2012 An Ecological Feasibility Assessment of the Proposed Weona Reserve
Walkway Development at Westmere. 27pp. (For Auckland Council)]
2
The route is indicated on the plan “Weona Coastal Walkway Stage 3 Detailed Plan, April
2012, Frame Group Ltd” (Figure 1). It was marked out on the ground by tape and pegs prior
to this survey being undertaken.
3
Figure 1.
Weona Coastal Walkway- Stage III.
4
2
VEGETATION AND FLORA
2.1.
The first 30 m or so of the route (at c. 681 m) passes across relatively open ground,
above a willow-filled watercourse. Onion weed (Allium triquetrum) is the principal
ground cover, through which small shrubs of Chinese privet (Ligustrum sinense) and
other exotic herbaceous and woody species are scattered. There are no significant
native botanical values here.
2.2.
The route then enters tall coastal scrub, and this kind of vegetation carries on mostly
continuous and uniform for the next c. 220 m. The canopy is generally at c. 5–8 m
high and its composition is equally divided between exotic and native tree species.
Most abundant among the former are shining privet (Ligustrum lucidum) and
hawthorn (Crataegus monogyna). No very old individuals of either species were
noted, but a fair number reach c. 12 m tall and 20 cm dbh (diameter at breast height).
The largest natives here are kowhai (Sophora chathamica), the half dozen or so trees
seen reaching a similar size to the privet and hawthorn. All seem to be in good health
and were flowering copiously at the time of survey.
Much more frequent than kowhai is mapou (Myrsine australis). It is the more common
regenerant too and can be considered the characteristic native tree of the site. Coastal
fivefinger (Pseudopanax lessonii) is common; some drawn-up individuals reach c. 8
m tall but mostly it forms large sprawling bushes. Karo (Pittosporum crassifolium) is
also common, although no large trees of it were seen. At several places towards the
edge of the house-properties upslope, silver tree fern (Cyathea dealbata) of up to c. 8
m tall forms dense groves, but this species is relatively uncommon as a regenerant in
the privet-mapou stands.
The native understorey, shrub and ground layers of this scrub have largely been
replaced by weeds, particularly climbing asparagus (Asparagus scandens). However,
as noted, mapou is regenerating well and hangehange (Geniostoma ligustrifolium) is
common in the least degraded places. In these places, hookgrass (Uncinia uncinata) is
frequent along with the native sedges Carex lambertiana and C. flagellifera, and
5
scattered, not particularly extensive, colonies of the ferns Doodia media,
Phymatosorus pustulatus, Asplenium lucidum and A. flaccidum.
Other native species seen within 5 m each side of the proposed route in the coastal
scrub were: Coprosma grandifolia (uncommon), Coprosma lucida (locally common),
Coprosma macrocarpa var. minor (uncommon, no large trees), cabbage tree
(Cordyline australis), cutty grass (Gahnia lacera),
mingimingi (Leucopogon
fasciculatus; juveniles only), mahoe (Melicytus ramiflorus; uncommon; no old trees
seen), pohuehue (Muehlenbeckia complexa), flax (Phormium tenax), leather leaf fern
(Pyrrosia eleagnifolia) and kauri sedge (Schoenus tendo).
2.3.
Manuka (Leptospermum scoparium) occurs only at one low-lying place (half a dozen
or so young individuals, to c. 3 m tall 5 cm dbh). Kanuka (Kunzea ericoides), karaka
(Corynocarpus laevigatus), pohutukawa (Metrosideros excelsa) and kawakawa
(Macropiper excelsum) are absent.
2.4.
The above composition of native species defines the site as one of fairly low fertility
that is subject to droughty periods.
6
3
CONCLUSIONS AND RECOMMENDATIONS
3.1.
None of the native species along the proposed route is uncommon in the Auckland
region or the Tamaki Ecological District.
3.2.
The proposed route stays well clear of the site's best botanical feature, its several large
kowhai trees. It hardly seems worthwhile to uplift, remove offsite and grow on the
rather few saplings the route passes over, but when the track is being formed such
plants could be translocated wherever they are encountered.
3.3.
Where the route passes between closely adjacent canopy trees, it will be necessary to
fell one of them. The choice is usually between hawthorn, shining privet and mapou.
The former two species do provide habitat for puriri moth larvae (that are not of
conservation concern) but are so common here as to make felling them (rather than
mapou) the right choice. Because the regrowth of hawthorn is very thorny, any cut
stumps of it should be treated with herbicide.
3.4.
Construction and use of a track through this section of coastal vegetation would not
diminish its botanical values or reduce its significance as a Significant Ecological
Area. The presence of the walkway is likely to result in a higher degree of pest plant
control and general vegetation maintenance than occurs at present and that would be a
positive ecological effect.
GD/1283 WEONA WALKWAY VEGETATION ASSESSMENT REPORT
25 SEPTEMBER 2012