Thursday, January 22, 2009
The West's Dying Forests
Along the West coast of North America from California to British Columbia, trees are dying faster, almost twice as fast as they did only three decades ago. It's a phenomenon that has wide-ranging implications for the region, its inhabitants and for the global environment. From The Guardian:
Trees in the western United States are dying twice as quickly as they did three decades ago and scientists think global warming is to blame.
In their surveys, ecologists found that a wide range of tree species were dying including pines, firs and hemlocks and at a variety of altitudes. The changes can have serious long-term effects including reducing biodiversity and turning western forests into a source of carbon dioxide as they die and decompose. That could lead to a runaway effect that speeds up climate change.
The forest survey, carried out by a team of scientists led by van Mantgem, is published tomorrow in the journal "Science." It showed that death rates of trees overall had more than doubled since 1955. In the Pacific north-west and British Columbia, deaths had doubled in 17 years. In California, the death rate took 25 years to double.
The data for the research was gathered by several generations of scientists counting trees over more than 50 years. It included forests in Oregon, Washington, California, Arizona, Colorado, New Mexico and south-western British Columbia. All were older than 200 years, with many being established more than 500 years ago. Death rates in old forests tend to be more stable since they mostly contain very old trees.