SEATTLE — While gradually warming global temperatures long have been seen as an environmental threat, a study released Monday suggested that the forests of the Pacific Northwest could see a substantial gain in productivity as the thermometer climbs. The bulk of the gains from climate change will be seen at higher elevations — above 3,000 feet — and in forests east of the Cascade Mountains, according to researchers at Oregon State University. Lower-elevation forests, where most of the commercial timber is harvested, could see reduced growth as a result of drier conditions. The study, published in the journal Forest Ecology and Management, is one of the first to look at a variety of climate change models and predict what might happen to the signature forests that are an economic and ecological mainstay of the West as the climate warms. Already, researchers have found detrimental effects from pest and disease infestation as a result of warmer temperatures that have begun killing off trees such as aspens, white bark pines and Douglas fir. But a warmer climate also could have a positive effect if, for example, more tree growth reduced the amount of carbon in the air, said […]