Fungus Slows Fir

摘要

A tree fungus that used to be a minor nuisance is now causing a major loss of growth in Douglas firs, a staple of the timber industry in the Pacific Northwest. Swiss needle cast disease has "become an epidemic" in some coastal regions and has significantly lowered productivity, says Bryan Black, a forest ecologist at Oregon State University in Newport and co-author of a study appearing this month in Forest Ecology and Management. The blight is being exacerbated by warmer springs and wetter summers, the scientists say.rnScientists used to think the disease, which causes needles to yellow and fall off, affected only young, fast-growing trees. But Black's team spotted severe growth declines in mature trees after taking tree-ring cores from 100-year-old stands on the Oregon coast. Compared with cores from western hemlock, the fir trees' growth rate has been stunted by more than 80% in the past quarter-century. The cores show the trees growing steadily until 1983, then "hitting a brick wall and shutting down," says Black. Alan Kanaskie, a forest pathologist at the Oregon Department of Forestry in Salem, says "this is the first study to rigorously show the decline in mature Douglas fir growth and link it to this disease."