Old tree deaths double across western US

 作者:黄沅     |      日期:2019-03-09 03:17:03
THE majestic old trees of the western US are disappearing twice as fast as they were three decades ago, and climate change is probably to blame. Philip van Mantgem of the US Geological Survey and colleagues collected data from old forests on the West Coast as well as in Arizona, Colorado and Idaho. In 87 per cent of the study sites, trees are dying faster than replacements can spring up. The Pacific Northwest was worst affected, with death rates doubling every 17 years (Science, DOI: 10.1126/science.1165000). “We may only be talking about annual tree mortality changing from 1 per cent to 2 per cent,