Raoul Island diary May 2009

By David Meagher

A May's Mossing

Isolated islands have a special fascination for biologists because it isn't easy to explain how all the plants and animals that are found on them came to be there. My particular interest is bryophytes - mosses and their relatives the liverworts and hornworts. For my PhD studies at Melbourne University I'm investigating the bryophytes of Raoul, Norfolk and Lord Howe Islands, which are all isolated islands of volcanic origin at approximately the same latitude in the western Pacific.

I hope to determine exactly what species are on these islands (only the moss flora have been documented in detail) and then compare them with regions where they might have originated, such as eastern Australia, New Guinea, New Zealand, New Caledonia and central Polynesia.

My favourite view on Raoul, from near
Mahoe summit, looking towards Titi Knob,
very reminiscent of Fiji, Samoa and Tahiti

Bryophytes on Raoul Island

About 50 mosses and 20 liverwort species have been found on Raoul since 1854, when William Milne and William MacGillivray made the first botannical exploration of the island during the voyage of HMS Herald, but that is far too few for a subtropical island the size of Raoul. A few weeks mossing on the island promised to uncover many species not previously recorded there, and perhaps add to the overall New Zealand flora.

So at the start of May, I found myself leaping onto Fishing Rock after a three-day voyage from Tauranga on the research vessel RV Braveheart. A breathless stagger up the short but steep trail to the main track, then a buggy ride to the hostel and an introduction to the facilities, safety matters, communication systems and so on followed quickly, and then it was off on my first mossing trip! That was an afternoon climb and scramble to Western Spring, one of only two permanent springs on the island. This little spring has a healthy population of Cyclodictyon blumeanum, a moss classified as endangered in New Zealand. It is mostly a tropical species, and the Raoul populations (there is a smaller one at Eastern Spring) are the southernmost known.

I spent a lot of time on the high ridges in forests dominated by giant pohutukawa and graceful nikau palms, with occasional tangly mahoe trees and a few other species. These higher forests (between 350 and 520 metres on Raoul) are wetter because they are often cloaked in cloud for much of the day, hence the name 'cloud forest' that is often applied to them.

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Papillaria crocea, a signature species
of the high altitude forests of Raoul

Most of the bryophytes grow on trunks and branches or on rotting logs. The most spectacular is the moss Papillaria crocea, which forms massive festoons on branches on the highest peaks. Among the liverworts, the most obvious is Plagiochila obscura, a big species that often covers the lower trunks of smaller trees. There is also an unusual epiphytic hornwort Dendroceros crispatus, that has not been recorded on Raoul before, but is quite common in higher forests. Some careful searching will also uncover dozens of tiny species often mixed together in soft mats, especially on rotting logs.

At lower elevations the forests are drier but are still dominated by pohutukawa and nikau palms. Ferns are less dense so there are more bryophytes growing on the ground, especially in open areas along the tracks. Probably the most common is the moss Pyrrhobryum parramattense, which forms large, fluffy clumps on just about anything. In the coastal woodlands dominated by ngaio, epiphytes are mostly tiny liverworts belonging to the family Lejeuneaceae or the genus Frullania. The bare soil of the crater is another interesting habitat for bryophytes, particularly the mosses Trematodon suberectus and Campylopus capillaceum, that seem happy growing on hot soil doused by sulfurous fumes and carbon dioxide.

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Collecting bryophytes

Collecting bryophytes is a simple but slow process. Every tiny habitat has to be checked for something different, and sometimes the same species can look quite different, or different species can look the same.

A specimen (usually the size of a 50 cent piece) is removed with a pocket knife and placed in a paper container (I use coffee filter bags because they don't disintegrate when they're wet, are easy to fold, and are reusable). A collecting number is assigned to the specimen and written in waterproof ink on the packet, and the number and collecting details such as the location, species name, substrate and general habitat are written into the field notebook. At the end of each day, I usually ended up with 20 to 40 specimens, which had to be carefully dried, catalogued, packaged and finally frozen to prevent fungal growth and insect attack.

In the end I had about 450 specimens to pack in a sealed container to take back to Tauranga and then to Melbourne, through a series of rigorous quarantine checks. As a rule of thumb, it takes three days in the lab to identify one days worth of collecting, so I'll have about two months of work ahead of me, which sounds like a pretty good job for a Melbourne winter!

Golfing on Raoul - a brief moment when
not collecting moss!

Events on Raoul Island in May

Two major events during May were the injury and evacuation of Andrew Cowie, the GNS team leader, and the changeover of volunteer crews. Andrew had the misfortune of being injured while working on installing a tsunami warning system on the island. He was evacuated by rescue helicopter to the mainland after a long night in the island's medical facility, an event that made headlines on the television news the next day.

For four hardworking volunteers, it was also their time to return to the mainland following six months of effort. They in turn were replaced by six keen newcomers arriving on the HMNZS Resolution.

It's not easy to say goodbye to Raoul, no matter how long you've been there. The following verse was written for the departing volunteers, but I think it is how everyone feels when they leave. It's based on a theme in Jack Kerouac's On the Road.

Sailing away

What is that feeling
When you're sailing away
From an island you love
And you come up on deck
And look out to sea
And find it is gone?

What is that feeling?
It's the ocean grown large
And it's swallowed you up
It's an outflowing tide
That's carried you outward
And it's too far to shore

It's the universe turned
And the night closed upon you
It's a darkened new moon
In a black starless sky 
What is that feeling?
It's farewell, and goodbye

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