Thursday, 12 January 2012

Plant life in Doubtful Sound

The second adventure in the Lewis & Clark College 2012 New Zealand course was a cruise through Doubtful Sound on the Fiordland Navigator.  Learning objectives included (1) the influence of fresh water in the fjord, especially since the outflow of the Manapouri Power Station brings additional large amounts, (2) bird recognition, and (3) an overview of the vegetation changes and introduction to key plant species.
We had permits to take small bottom samples with a grabber under supervision of Dr Lucy Jack from Otago University, who also had brought a remote-controlled mini submarine with a camera for viewing marine life.  The night before, Lucy outlined the features of the environment and some of the research findings of the team she works with.
The bird life was evident from the ship and also from kayaks and tender boats.  Among others we saw variable oystercatchers (with chick), kaka, tomtits, shags, and a mollymawk at the fjord entrance.
Doubtful Sound from Willmot Pass
The plant life changes dramatically from the head of the catchment at Willmot Pass to the open coasts.  The road at the pass is close to timberline which is about half-way up the mountains there.  Above timberline snow tussock and alpine plants predominate, but the forest at the pass is dominated by silver beech, Nothofagus (sect. Lophozonia) menziesii, with ribbonwood (Hoheria lyallii) on slips and roadsides.  This is the zone of highest rainfall, which suits silver beech, although we saw it in dry conditions.
Black beech, Nothofagus solandri.
Black beech, Nothofagus (sect. Fuscospora) solandri, is dominant at sea level in the inner fjord.  Other plants here include fuchsia (Fuchsia excorticata), pate (Schefflera digitata), and putaputaweta (Carpodetus serratus).  It was a nice surprise to see Breaksea Girl moored here; I went to Campbell Island on her in 2004.
Putaputaweta, Carpodetus serratus.

Breaksea Girl
In the outer fjord, and especially on the shores of Secretary Island, rimu (Dacrydium cupressinum) is more common, along with yellow-silver pine (Lepidothamnus intermedius).  Other podocarps there include miro (Prumnopitys ferrugineus), tanekaha (Phyllocladus alpinus), and totara (Podocarpus totara).  Black beech is abundant here too.  Rata was also common, a few still in flower.
Southern rata, Metrosideros umbellata, in flower.
Outside the fjord, rocky coasts are exposed to the full force of the westerlies and the salt spray they carry.  Veronica (sect. Hebe) elliptica and Brachyglottis rotundifolia dominate the coastal scrub.
Salt-tolerant coastal scrub on one of the islands that guard the fjord entrance
The huge landslide below was caused by the 2003 Secretary Island earthquake (M 7.1).

A prominent plant on the rocky shores of the fjord is Olearia oporina, which was flowering freely.  
Olearia oporina
Tree branches overhanging the water were heavy with epiphytes, including the orchid Dendrobium cunninghamii flowering freely.

Epiphytes on beech.
Overnight we were treated to heavy rain, so the waterfalls were in full flow next morning as it cleared. 

The second night was clear and many students stayed on deck until midnight to watch the Southern Cross and other unfamiliar stars rise above the surrounding peaks.
The trip was an excellent introduction to temperate New Zealand rain forests, sandwiched between the dry lands of Central Otago and the beech-free zone on Stewart Island.  Access by land to these extreme forests is impossible, certainly in the time we had available.  The crew of Fiordland Navigator gave the students and staff an unparalleled wildlife trip.

No comments:

Post a Comment