New Caledonia: plant paradise of the Pacific
The Pacific Ocean might be mostly water, but over twenty-seven thousand islands are dotted across its shimmering surface. On each speck of sand and stone, life has found a way to survive, adapt, and diversify; what little land there is in this sprawling sea supports a vast array of unique species. But one island nation stands head and shoulders above the rest – known for both its coral and its conifers, welcome to New Caledonia!
It ain’t easy being green – unless you live here
New Caledonia could be the poster child for cultural diversity; the native Kanak people have mingled with French colonisers and waves of Asian and Polynesian immigrants to create a melting pot with truly international flavour. Scientists, however, are far more interested in the diversity of New Caledonia’s leafy residents.
Many of the Pacific’s plant species are found on hundreds of different islands – and sometimes as far afield as Asia and Australia. New Caledonia, on the other hand, simply won’t be outdone when it comes to individuality. An astounding four in five of New Caledonia’s more than three thousand plant species are endemic – found nowhere else on Earth. From the world’s most ancient flowering plant to its only parasitic pine tree, New Caledonia is filled to the brim with botanical sensations. How did all this richness come to be? The answer’s buried in the soil, and across the sea.
Bon voyage, baby
Head out for a bushwalk on this island paradise, and there’s a good chance you’ll be reminded of an Australian nursery. Some of our most iconic plants, like grevilleas and bunya pines, crop up all over this far-flung nation. But these aren’t imports – they travelled across the ocean with the island itself!
Most of the islands in the Pacific formed from volcanic eruptions, mere babies in geological time. New Caledonia is much, much older: it was born from an ancient landmass called Gondwana, which once joined the southern continents together. The breakup of Gondwana began almost 200 million years ago (mya), but around the same time as the dinosaurs died out (65 mya), New Caledonia broke away from eastern Australia, and drifted north.
Alone in the big blue, this enduring isolation has given the plants of ancient Australia time to evolve into a range of new species. The stable, moist climate of the tropics also helped these old groups to flourish (particularly in the mountain rainforests), while they died out in Australia as deserts gradually replaced the lush woods of old. To botanists, New Caledonia’s flora is a whisper of what once grew upon our red dust.
If I had a nickel for every time…
Visit the southern hills of New Caledonia, and you might be reminded of this same red dust – but the local dirt isn’t from Uluru. Geologists think this colourful soil formed well after New Caledonia split from Australia, when a portion of the Earth’s mantle poked above the crust. This rumble from below left behind a rare, strange rock known as serpentine. The soils that form from serpentine are equally bizarre: rich in toxic metals, and lacking the nutrients that plants need to grow. Of the many toxic metals, nickel is especially abundant – New Caledonia holds a whopping one-tenth of the world’s reserves.
Nickel deposits are great news for mining companies, but pure poison for most plants. Some of New Caledonia’s plants have bucked the trend and adapted to this lethal toxin, moving onto the free real estate of these serpentine wastelands. The untapped potential of this new environment led to another explosion of diversification, as nickel-loving plant species gradually spread and competed to fill gaps in the landscape. Today, the result is an alien shrubland that coats the rolling slopes and valleys of the south – only 9% of the species here can be found elsewhere in New Caledonia, let alone the world.
A defoliated future?
It should be clear by now that this humble archipelago has been blessed with nature’s bounty. But will this bounty last forever?
The local fossil record shows that, like most of the Pacific’s islands, big extinctions followed human arrival. Islands are naturally susceptible to human disturbance, and this French outpost is no exception. Giant turtles, snail-munching land crocs (really!), and a bevy of hapless birds have all vanished from New Caledonia since the Kanaks first landed on its pristine beaches.
The story for plants is less clear – they don’t have bones! – but we do know that land use across the nation is putting on the squeeze. A horrifying ninety-eight percent of western New Caledonia’s dry forests have already been wiped out for mining and development. Will New Caledonia still be an arborescent ark in the centuries to come? That depends on us.