GRANTS PASS, Ore. (AP) — Big changes are in store for the nation's forests as global warming increases wildfires and insect infestations, and generates more frequent floods and droughts, the U.S. Department of Agriculture warns in a report released Tuesday.
The compilation of more than 1,000 scientific studies is part of the National Climate Assessment and will serve as a roadmap for managing national forests across the country in coming years.
It says the area burned by wildfires is expected to at least double over the next 25 years, and insect infestations often will affect more land per year than fires.
Dave Cleaves, climate adviser to the chief of the U.S. Forest Service, said climate change has become the primary driver for managing national forests, because it poses a major threat to their ability to store carbon and provide clean water and wildlife habitat.
"One of the big findings of this report is we are in the process of managing multiple risks to the forest," Cleaves said during a conference call on the report. "Climate revs up those stressors and couples them. We have to do a much better job of applying climate smartness ... to how we do forestry."
The federal government has spent about $1 billion a year in recent years combating wildfires. Last year was the warmest on record in the lower 48 states and saw 9.2 million acres burned, the third-highest on record, according to the National Oceanic and Atmospheric Administration's website.
Insect infestations widely blamed on warming temperatures have killed tens of millions of acres of trees.
Forest Service scientist James Vose, the report's lead author, said the research team found that past predictions about how forests will react to climate change largely have come true, increasing their confidence in the current report's predictions.
The report said the increasing temperatures will make trees grow faster in wetter areas of the East but slower in drier areas of the West. Trees will move to higher elevations and more northern latitudes, and disappear from areas on the margins of their range.
Along with more fires and insect infestations, forests will see more flooding, erosion and sediment going into streams, where it chokes fish habitat. More rain than snow will fall in the mountains, shortening ski seasons but lengthening hiking seasons. More droughts will make wildfires, insect infestations, and the spread of invasive species even worse.