Botany trip : ‘Pack Track West’, Wainuiomata Catchment
29 Nov 2009
Since Greater Wellington Regional Council opened the Wainuiomata/Orongorongo catchments to guided groups ten years ago, numerous club members have visited these valleys, and their magnificent, unlogged forests. Whether tramping, or botanising, we are always in awe of the sight of these native forests in near perfect condition, and so close to home.
On this, the second TTC botany trip in the catchments, we botanised the Pack Track. It was built in the 1920s, to take supplies by packhorse to tunnellers who were drilling the east end of the 3.2-km tunnel in which a pipe was to be laid to bring water from the weir in the Orongorongo Valley to the now-decommissioned Wainuiomata Dam.
We parked at the ‘wacke pit’, where rock from the west end of the tunnel was dumped. From there, each armed with a list of the botanical, Maori and common names of about 170 native plant species, we began botanising, discussing the features used to identify trees, shrubs, climbers, ferns, orchids, grasses, sedges, rushes and herbaceous plants. We practised using several senses to identify plants:
: seeing the opposite leaves of coprosmas, the alternate leaves of rewarewa, and the exquisikoru of giant umbrella fern
: tasting native cress and horopito
: feeling the soft fronds of cyathea tree ferns, and harsh fronds of dicksonia tree ferns
: smelling stinkwood/hupiro leaves, and hangehange flowers.
We were rewarded by several species in bloom, including hinau, heketara, kamahi, rewarewa, rangiora, and the tiny panapana/native cress. The sight of a massive vine of northern rata descending the 1-m trunk of a rimu had us marveling at this phenomenon. Perhaps a few centuries ago, a tiny seed of the rata had been blown into the crown of the rimu, grown there perching for a century or more, then its root grew down the rimu, where it gained access to soil nutrients, and more water. We noted that the rata had ‘girdling roots’ around the rimu trunk, and learnt that the rata is an epiphyte, not a parasite. The rimu merely dies eventually of old age, perhaps hastened by the rata competing with it for light, and later for soil nutrients and water.
We saw a looper caterpillar wending its way across a heketara flower, and often heard korimako/bellbirds, kakariki, kereru and miromiro/tomtits, calling near the track.
At the request of the tutor of a post-graduate student at Victoria University, Chris used his collection permit to collect fronds of a fern, kiwakiwa, so that she can test them as part of her project on the anti-bacterial properties of several plant species.
Despite the best efforts of the regional council, the forest is not pest-free. We saw pig rootings, and vegetation browsed by deer, goats or possums. Also, parts of the forest floor were covered by plants unpalatable to deer, pigs, goats and possums, e.g., bush rice grass, piupiu/crown fern and horopito.
On the other hand, we noted the good condition of most of the giant northern rata crowns we saw in the valley of George Creek. This species, so favoured by possums, can be killed by browsing, so the council’s possum-control work is effective. After discussing the possible origins of the patterns in the forest canopy in the upper reaches of this true right tributary of George Creek, we turned back at the steep gully about 0.5 km from the point where the Pack Track crosses the ridge to Puketaha.
We thank GWRC Ranger, Scott Farrell, for approval to visit the area, and Barbara Mitcalfe for help compiling the plant and bird lists.
- Party members
- Jean Chapman, Ken Fraser, Lois Hope, Chris Horne (leader/scribe), Mary Kane, Nina Price, Jill Stewart, Cathy Wylie