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Science: Opening time could come later in the greenhouse

作者:漆雕疼    发布时间:2019-03-04 02:03:03    

THE SPRING landscape of Britain will never look the same once the greenhouse effect is in full swing, according to researchers at the Institute of Terrestrial Ecology at Penicuik in Scotland. Maureen Murray, Melvin Cannell and Ron Smith simulated the warming of the climate to find out how it affected the opening of buds on trees. They conclude that although global warming will lead to an earlier spring in temperate regions, it will also delay the opening of some winter buds (Journal of Applied Ecology, vol 26, p 693). The reason for this apparent paradox is that the winter buds of most temperate species of tree need a period of ‘chilling’ in order to wake them from their winter dormancy (This Week, 23 September). Trees need different periods of chilling, so those that are chilled longer than necessary in our present climate will open earlier as the climate grows warmer. By contrast, buds that need a long period of chilling would still be partially dormant when spring came, and so would take even longer to open than usual. The overall effect would be a change in the order in which trees come into leaf. To test their theory, Murray and her colleagues compared the times at which the buds of 15 species of trees open, both outside and inside a greenhouse that was intended to simulate a warmer world. They studied the trees at Edinburgh and at Braemar, which, being at a higher altitude, is colder. Beech buds, which need a long period of chilling, opened up to six days earlier in Braemar than in Edinburgh. The buds of other species opened earlier in Edinburgh than in Braemar. In the researchers’ greenhouse, the increased temperature brought forward the time that some trees open. The buds of Sitka spruce, for example, opened about two weeks earlier at both sites. For other species, such as the hawthorn,

 

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