Revival of rare plants free from rabbits

Press, 4 March 1988, Page 19

Revival of rare plants free from rabbits

By

DERRICK ROONEY

The fantastic eroded landscape of Philip Island — ‘like a raw moonscape" — and :he location of supposedly “extinct!’ species, which had reappeared i since the * Australian Wildlife St rvice eradicated rabbits from the island, were highlights of a recent visit to the Norfolk Island group by a Christchurch scientist. The scientist, Mr W. R. Sykes, of the D.S.I.R. Botany Division, visited the island territory, at the request of the Australian National Parks and Vildlife Service, to survey and report on the status of the island’s ■ rare and endangered plant splecies. He was joined on the two-week visit by a Wellington! ecologist, Dr lan Atkinson, who was studying the impact ofj introduced rodents on the island’s [bird population. j A dramatic declinp in the bird population of. Norfolk Island since World War II has been attributed to the accidental introduction of a new variety of rat.

Norfolk, an island with no indigenous people, has politically anomalous status, pot-plant seeds and tourism as its two, main industries, and a turbulent history which began 200 years ago with the establishment of an infamous penal colony to which Britain banished the riff-raff and the nuisances of trie Empire. The prisons, maintained today as a tourist attraction, closed in

1856, but immediately afterwards the island was repopulated by “free." settlers — descendants of the Bounty mutineers and their Tahitian •wives who were forcibly removed! from Pitcairn Island on orders from London, and resettled on Norfolk. Some -of the Pitcairners subsequently returned home, but there are still many people of Pitcairn descent on Norfolk and, says Mr Sykes, they still refer to themselves as “islanders” and to the other Norfolk inhabitants as “mainlanders.”

Norfolk Island is part of Australia but its 1200 inhabitants do not get the opportunity to vote in State elections, unlike other Australians; the island is administered directly from the capital, Canberra. In recent years, says Mr Sykes, the islanders have been campaigning vigorously for increased autonomy. The climate is subtropical, and growth continues year round, but it is not quite warm enough for tropical crops such as coconuts. The main industries,: apart from tourism and some fishing, are growing seeds of the famous Norfolk Island pine (Araucaria excelsa) .and the Howea palm for export. The latter, better known as kentia palm, is one of the world’s most popular pot plants. The pine is also a popular pot plant but will grow outside in favourable situations in many parts of New Zealand. One of the best-known groups is on the beachfront at Sumner. However, unlike the radiata pine which is the basis of New

Zealand’s forest industry’, the Norfolk pine is far from endangered in its native state. In fact, says Mr Sykes, it is almost übiquitous on both Norfolk itself and the adjoining Philip Island. The main island is only 7.5 km long, 1 and has an area of 3450 hectares. Philip Island — named for Lieutenant Philip Gidley King; commander of the first convict party landed on Norfolk — is a short distance offshore, and much smaller. Both are of volcanic origin. Mif Sykes has visited Norfolk, privately, twice before, and has a professional as well as personal interest in the island’s botany — one of his tasks in recent years has [been to keep tabs on the flora of the Kermadecs and Raoul Island, New Zealand's territory a.t similar latitude. He believes ‘it was partly because of this, I and partly as a result of contacts he established on the island during his earlier "working holidays,” that he was asked to make! the survey. His guide was Mr Owen Evans, an islander of Pitcairn descent who has an extensive knowledge of the island flora and its distribution. i As in the Kermadecs, says Mr Sykes, introduced weeds present the greatest threat to the indigenous vegetation. One of the worst culprits is the purple guava, a shrub cultivated as a garden fruit in northern New Zealand. This has never naturalised in .mainland New Zealand, but is a nuisance on Raoul and the Kermadecs. On

Norfolk, says Mr Sykes, it is rampant. One of the very few plants capable of invading underneath a dense forest canopy, it is found al! over the! island, right up to the top of Mt Bates, which at 319 metres is the highest point on the island.

Another problem tree weed is the African olive, a subspecies of the European olive with small, worthless fruits. African olive now occupies large areas on Norfolk and is spreading on Philip, from which,the last feral browsing animals were removed four years ago. On the credit side, says Mr Sykes, indigenous vegetation has also begun to repopulate Philip’s raw, eroded landscape. Since the rabbits went a rare abutilon, last seen on Norfolk many years ago and believed to be extinct, has reappeared on a cliff on Philip. Mr Sykes brought back colour photographs of it. He also brought back specimens of an endemic grass from Philip, long listed as extinct.

The grass, a species of Elymns, has last been collected in 1912. As often happens with botanical discoveries, Mr ‘ Sykes! stumbled across it by ' sheer chance. “I was hurrying back to the beach to get on board the boat when I spotted two or three small patches of a grass that looked different,” he said. "I thought, 'That looks like the extinct species'.” He hurriedly collected ' a few

specimens, and subsequently sent some to the Royal Botanic Gardens, Kew, for study by specialists. "Well done — what a thrill!” began the letter which came back, confirming Mr Sykes’s identification of the grass. Mr Sykes believes the species was probably never "extinct,” but survived on the cliffs and repopulated the grassland when the rabbits were removed. Since the Kew letter arrived he has telephoned the ranger on Norfolk and asked him to look for more populations. In consequence of these finds, high hopes are entertained for the reappearance of another Philip Island species, a beautiful

flowering pea which has not been seen for many years. A very rare species which is thriving on the relief from browsing is a hibiscus, H. insularis, a shrub with striking crim-son-eyed cream • flowers. This is known only from one gully on Philip Island, where there is patch about five metres square which may consist of only one plant. Ironically, says Mr Sykes, this colony has survived largely because it is ! surrounded by African olive, which has protected it from erosion. The rare hibiscus is now being cultivated on Norfolk Island, and may eventually find its way into gardens around the Pacific. As

far as he knows, says Mr Sykes, it is not yet grown! in New Zealand. However, he has seen it in Australia, in the Sydney Botanic Gardens. On Norfolk itself, I says Mr Sykes, the vegetation is interesting in that the trees have affinities with species from the northern Pacific, whereas the herbaceous plants have more affinity with New Zealand species. Many of the plants have colourful popular names — one thorny climber is known as “devil’s guts.” Among the rare species that Mr Sykes encountered was a tree belonging to the Amaranthus family, most members of which

are small herbaceous plants — one is cultivated as a grain in South America, two are wellknown Asian vegetables, and one is grown as a flowering annual. Another oddity is the birdcatcher tree (Pisonia), whose fruit have a sticky coating that can snare small birds. This was first collected and named about 1803 by an Austrian botanist, Ferdinand Bauer, who also collected in Western Australia.

Yet another rarity is the Norfolk Island mahoe, an endemic species of Melicytus closely related to the familiar New Zealand coastal shrub. A subspecies of the!New Zealand mahoe also grows on Norfolk, but is not rare.

‘lslandersf and ‘mainlandlers’

High hopes for some species