One of the world's oldest and largest living trees stands just a few steps from a major highway in New Zealand's Waipoua Forest. The Tane Mahuta, or "Lord of the Forest," in the language of the indigenous Maori people, is estimated to be 2,000 years old.Its silvery trunk, more than 14 feet in diameter, rises out of the rain forest like a monument. Its vast, elegant canopy, 169 feet high, spreads out like the arches of a Gothic cathedral.
Tane Mahuta, pronounced Tar-nay Mar-hoo-tar, is a kauri tree, a New Zealand icon, found on stamps, tea towels and postcards. And to many New Zealanders, it's a symbol of recent efforts to protect the environment after decades of heavy logging. "This tree connects you to the past," says John Beachman of the New Zealand Department of Conservation. "Some of these trees were here before anyone came to New Zealand."
But kauri trees are in trouble. Last year, people started reporting dead or dying specimens. Some had spindly yellowing branches and sap oozing from their mighty trunks; others had lost their leaves and had lesions on their gray bark. Stephen King, a kauri reforestation expert, watched helplessly as a healthy 600-year-old kauri near his home in the Waipoua Forest turned brown and died in just two months. "A beautiful big tree taken out just like that," says King. "It's hard to believe."
The kauri, Agathis australis, is a conifer that belongs to an ancient lineage. Its close ancestors evolved during the Jurassic Period, some 135 million to 190 million years ago. Kauris that lived 50,000 years ago have been found in swamps, some so well preserved that artists make carvings out of their timber. When the Maori reached New Zealand from eastern Polynesia about 1,000 years ago, they felled the big trees to make carvings and waka canoes. European settlers found the trunks of young kauri to be ideal for masts and for houses. The trees were also bled for their sap, or gum, used as an ingredient in paints and varnishes. Farmers cleared even more of the forest to make way for crops.
Wild kauri forests, which once covered more than one-tenth of New Zealand's North Islandósome 3 million acresóhave been reduced by more than 99 percent, to some 10,000 acres. King estimates that there are 10,000 mature trees left and fewer than 100 that are more than 1,500 to 3,300 years old. Forest biologists say that none of those historic specimens have yet been afflicted by the outbreak that has caused such alarm. About 1 percent of wild kauri have been struck by the disease.
Six months after the first dead kauri trees were found, at Maungaroa Ridge, near popular Piha Beach, scientists named a likely culprit: a microscopic fungus, a type of Phytophthora. Ominously, the fungus is a relative of the blight that ravaged Ireland's potato crop in the mid-19th century and caused the Great Famine. It's also related to the pathogen that causes sudden oak death, which was first found in California in the mid-1990s and has spread to Oregon, killing at least a million trees, mostly black oak, tanoak and coast live oak.
New Zealand's stricken trees have attracted expert attention. Matteo Garbelotto, a plant pathologist at the University of California at Berkeley, who has studied sudden oak death and observed the kauri outbreak in New Zealand last year, says that "once you've introduced a Phytophthora, it's almost impossible to get rid of it. They like to be in live plants, and they kill them before you know they're there."
Garbelotto says his first encounter with a kauri was eye-opening. "People kept saying, 'You've got to see the kauri, you've got to see the kauri,'" he recalls. "But being there seeing those forests, it was a stunning experience. I realize why [New Zealanders] are doing so much to protect them."
Where the fungus came from is a mystery. It was discovered on New Zealand's Great Barrier Island in 1970 but may be a new arrival to the main islands. The nation's wildlife, long protected by sheer isolation, has few natural defenses against predators or contagious diseases that might hitch a ride to the islands on a ship or airplane. The whole country, says Beachman, the conservation official, is "a bio-security nightmare."
And fungi are tough to fight. Peter Maddison, an entomologist and president of the Royal Forest and Bird Protection Society, says one possible approach to stemming the spread of this fungusóremoving dead kauri trees and neighboring debrisóis unlikely to succeed, if only because fungi produce billions of airborne spores. King says he has had some luck spraying infected kauri leaves with phosphoric acid, which seems to delay the growth of the fungus, and suggests spraying New Zealand's trees from airplanes. Meanwhile, he is growing thousands of kauri seedlings in a nursery in the Waipoua Forest that are ready for replanting; other forestry experts plan to take seeds from Tane Mahuta and grow seedlings that will be the core of a new forest.