Botany trip: three Karori reserves
Sunday 20 November 2011
We met near the bus stop by Appleton Park, where everyone received a copy of the plant lists prepared during a recce a few days previously. Eighty-seven native species and 44 weed species were listed, each plant with a number, its botanical name, Māori name and common name, so that when someone recognised a plant, they could call out their choice of either the number, the botanical name, the Māori name, or the common name. People could then tick the plant on their own copy of the list. The lists also included native and introduced birds heard or seen during the recce. Someone asked why the plants on the lists were divided into plant categories, e.g. Tree, Liane (vine), Fern, Grass, Sedge, etc. We explained that this division is based on concepts such as growth form and methods of reproduction.
Along Waiapu Road, heading toward Karori Sanctuary, we looked across the valley of the Te Mahanga branch of Kaiwharawhara Stream at the regenerating forest of Birdwood Reserve on the steep, east-facing scarp of the Wellington Fault. Here we invited people to see if they could identify various tree species from a distance, for example the prominent spires of rewarewa, emergent above the canopy of kohekohe, māhoe, mamaku tree ferns, and other species. This mostly indigenous ecosystem is subject to pest control, and for this reason, a skeleton is all that remains of the huge sycamore tree recently killed by Wellington City Council’s (WCC) weed team. Its wind-borne seeds may germinate for decades to come, and so new plants will need removing. Opposite the sanctuary office, we walked down the track to St John’s Pool, once a popular public swimming pool formed by a concrete dam. Soon we spotted the entrance to the adit of the Golden Crown mine, one of five in the valley in the 1860s – 1880s. On the stream terrace grow tree fuchsia, the world's biggest member of the genus. Uptrack we added tītoki to the list, then admired a huge 100+-year-old puka, Griselinia lucida, (see the December Tramper), and a very large ngaio. The diversity of native plant species in this reserve, and the opportunities to discuss this, were such that we did not reach the sanctuary fence, a conveniently sunny spot, until lunch-time.
Well-fed, we sped south along the weedy “Roller-coaster” track beside the fence, to the Campbell Street entrance to John’s Track, Wright Hill Reserve. The track zigzags gently towards the summit, offering plenty of chances to talk about the trackside plants. The forest here is at an earlier stage of regeneration than that in Birdwood Reserve, so it is lower in stature, and with a different community of plant species, notably the highly-invasive, long-lived, woody shrub, Darwin's barberry. As we tramped along to the lower carpark, we saw tōtara planted by a community group, small-leaved Coprosma species, and views over the harbour, suburbs, and ranges.
Finally, we descended Burrows Reserve via Burrows Track, passed a huge māhoe, and were relieved that WCC's weed team had drilled and poisoned the large, invasive English holly that was still proving reluctant to die. We noted that Greater Wellington Regional Council maintains a network of possum bait stations here. Shortly there came what proved to be an identification puzzle which at first we thought was a huge, five-trunked exotic, with narrow, pale, toothed, leaves. We later identified it as Hoheria sextylosa, a lacebark/houhere that occurs naturally, but sparsely, in the Wellington region, unlike Hoheria populnea, a ‘garden-escape’ lacebark which does not occur naturally in the Wellington. It has broad, sometimes purple-backed leaves and unfortunately has become weedy in Wellington's indigenous ecosystems. Soon we reached the valley floor, passed several magnificent tree fuchsia/kōtukutuku, and emerged in suburban Karori.
Thanks to the group’s twelve pairs of sharp eyes, we had added to the lists ten native plant species and seven weed species - a satisfactory result on a satisfying day out, close to home. WCC, DOC, and the NZ Plant Conservation Network will be sent a copy of the final lists.
- Party members
- Megan Evans, Richard Grasse, Diane Hill, Warwick Hill, Chris Horne (co-leader and scribe), Liz Martin, Barbara Mitcalfe (co-leader and scribe), Nicola Robertson, Peter Shanahan, Lesley Shand, Ingrid Ward, Marris Weight.