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Uprooted

发布时间:2019-03-07 12:17:01来源:未知点击:

By Stephanie Pain EXTINCTION looms for some of the most ancient trees on Earth. A quarter of the world’s conifer species are under threat, many of them survivors from the age of the dinosaurs. And more than one in ten species is likely to disappear in the next few decades, the World Conservation Union (IUCN) warned this week in its Action Plan for Conifers. Only three specimens remain of the world’s rarest conifer, the Chinese species Abies beshanzuensis. And another Chinese species, Thuja sutchuenensis, has disappeared from the wild altogether, surviving only in cultivation. Logging, mining, wildfires, agricultural and urban development—even ozone pollution—are all taking their toll. The greatest diversity of conifers is at low latitudes and in the tropics; forests in the north have billions of trees but few species. “People perceive conifers as very common because they think of vast northern forests of pines and firs. They don’t realise the great majority are more isolated—growing on the fringes of the Pacific, on tropical mountaintops or islands or at the tips of the southern continents,” says Christopher Page, one of the plan’s authors. “It’s these we are especially worried about.” Many of these species are relics from the Mesozoic era that began 225 million years ago. Once flowering plants arrived, the vast conifer forests disappeared. Many species died out, others retreated into smaller refuges, often in lands with harsh climates or poor, sometimes toxic soils. “These are areas where whole genera and families are threatened with rapid extinction. No animal group is in quite such jeopardy,” says Page. Many ancient species are sought after for their dense, rot-resistant timber. “The most ancient conifers are also the most slow growing,” says Page. “For some, recovery could take a thousand years.” The new action plan shortlists 42 conifers for urgent attention and nine “hotspots” where conservation will protect at least eight species. It suggests areas that should be protected against logging, mining and fire, and regions where the conifers’ shrinking habitat must be restored. As an insurance policy, says Page, it is vital to store seed in seedbanks and plant the rarest conifers in safe havens such as botanic gardens. The Pacific island of New Caledonia is one of the top priorities. The island has 43 unique conifer species. Strip mining of the metal-rich soils is a serious problem. Ironically, these conifers have hung on this long because they have adapted to growing in metal-rich soils—the ones now sought after by miners. Conifers could also prove to be a valuable medicine chest. One species, the Pacific yew (Taxus brevifolia), has already provided the anticancer drug Taxol. “These ancient plants have all sorts of properties that are very different from modern plants,” says Page. “Who knows what else we might find?