TRIP REPORT : Whareroa Farm, Mackays Crossing

Saturday 3 November 2007

Ann Evans with a pair of very large Carex secta. Photo: Rodney Lewington.

This was a combined BotSoc and Guardians of Whareroa trip.   Ann Evans of the Guardians described the history of the farm.   It was covered in lowland broadleaf-podocarp forest until the 1850s, but was then subjected to draining and clearing for cattle and sheep farming, until taken over by the Defence Department for the US Marines in 1942.   After WWII, it was transferred to the Department of Lands and Survey, then Landcorp.   During the 1980s it was a farm park open to the public.   It was bought by DOC in 2005.   Permission to visit the farm is now usually easy to obtain from DOC Waikanae.

We first explored the wetland area near the gate, where flaxes, cabbage trees and Carex spp. from a nursery in Taupo have been planted.   Many of them have yellowing of the leaves, possibly because of “yellow-leaf”, the pH of the soil, or the provenance of the plants.   The small streams have retoreto / Azolla rubra and three-square / Isolepis prolifer in abundance.   Other wetland plants include Hydrocotyle elongata, weeds such as watercress / Rorippa nasturtium-aquaticum and water celery / Apium nodiflorum, and a variety of introduced pasture grasses.   On the north bank, plantings include kawakawa, looking stressed in the sunlight away from the bush edge, and karamu / Coprosma lucida.   Releasing the planted species from the grasses and weeds may cause more stress, if all shade is lost.   Pest animals include hares, rabbits, possums, feral goats and sheep.   DOC has employed a possum hunter.

The remnant bush on the slopes includes mahoe, karaka and rangiora at the edges.   The undergrowth has been browsed by cattle.   The canopy comprises kohekohe, tawa and some emergent rewarewa.   Ground ferns include Asplenium hookerianum, and hound’s tongue.   Akatea / clinging rata and kareao / supplejack vines, and ota / leatherleaf fern grow on many trees.

When we left the remnant we followed a tributary to the northeast, past a stand of gum trees acting as a nursery for native flora, and inhabited by tui and eastern rosella.   The few live totara on the hill, and many dead, headless, mamaku, bore witness to spraying done six years ago.   Gorse is invading the sprayed area.   Nearby, two Carex secta, over 1.5 m tall, looked spectacular.

Chris Hopkins inspects a mass of adventitious roots. Photo: Rodney Lewington.

Following a well-earned cuppa, we moved south to a second bush remnant on a north-facing slope.   The canopy includes miro, kahikatea, kohekohe, tawa, narrow-leaved maire, and kanuka, with some clinging rata / Metrosideros perforata at the edges.   The forest is devoid of understorey, since cattle have been excluded only since June 2007.   Many small seedlings are appearing at the bush edges, including mahoe, taupata, kawakawa, karaka and Asplenium hookerianum.   On the eastern side of the remnant are several juvenile Streblus banksii trees.   Nearby we saw the orchid, Earina mucronata, in flower.   We lunched near a 7 m hanging mass of adventitious roots – were they clinging rata – a dead vine climbed the supporting tree – or were they pohutukawa growing epiphytically?   Which ever they were, they were very impressive.

In a paddock, we found a large, mature, ewekuri / large-leaved milk tree / Streblus banksii.   It is infected with galls and some trunk rot, but otherwise appears healthy, despite the exposed site.   The third remnant we visited was at the mouth of Ramaroa Stream, a southern tributary of Whareroa Stream.   It has been fenced for about 20 years and has very little cattle damage.   The dominant trees are kohekohe with matai, titoki, with a kawakawa understorey, rata and supplejack vines, and Pseudopanax hybrids.   The groundcover is mainly ferns and kohekohe seedlings.   Tradescantia and arum lilies are encroaching on its boundaries.   We went upstream to an historic reservoir – it used to supply Paekakariki – and the site of the old homestead surrounded by large pohutukawa.

We had a great day exploring, listing many species previously not known on the farm.   The lists have been sent to DOC and Greater Wellington Regional Council.   The weather, predicted to be poor, was fine until we returned to the car park, and then mist and drizzle arrived.

Participants :   Bev Abbott, Dave Allen, Barbara Clark, Rae Collins, Gavin Dench, Barry Dent, Ann Evans (co-leader), Sue Freitag, Chris Hopkins, Chris Horne, Brenda Johnston, Michael Keith, Rodney Lewington, Pat McLean, Barbara Mitcalfe, Karen Palmer (co-leader / scribe), Darea Sherratt, Sunita Singh, Jonathan Waterworth.