New study focuses on drought-stricken California forests
A rising tide of insect infestations, tree mortality and wildfires — all caused by global warming — has resulted in political pressure for more logging in U.S. Forests, but there’s plenty of research showing that cutting down trees doesn’t do much good and can even increase the fire danger.
Exploring alternative options for strengthening forest resiliency, researchers with the U.S. Geological Survey and the National Park Service recently found that thinning forests with prescribed fires can reduce drought.
“There is a lot of research showing that climate change is already increasing drought frequency and severity,” said USGS forest ecologist Phillip van Mantgem. “Our study indicated that, when some trees were removed using prescribed fire, the remaining trees were more likely to survive during the drought. The use of prescribed fire prior to drought may help forests by allowing the remaining trees to have more water during times of stress.”
The research focused on low elevation, drought-stricken conifer forests in Sequoia, Kings Canyon and Yosemite National Parks, examining data from almost 10,000 individual coniferous trees, ponderosa pine, white fir and Douglas fir. They used this information to estimate the risk factors involved in tree mortality, and found greater tree mortality in forests that were not burned before the onset of drought in 2012. The study is published in the journal Fire Ecology.
“If current warming trends continue, we can expect to see more frequent tree deaths following drought, which can lead to substantial changes in forests,” said Dr. van Mantgem. “But managers may be able to blunt the effects of drought by using prescribed fire as a tool for forest health.”
The study took into account the impacts of the drought in 2012 and 2014, with more research planned to include the continued effect of drought in 2015.
“Understanding the relationship between drought, fire, and tree mortality from fires adds some important wrinkles to how we manage forests,” said Tony Caprio, a fire ecologist with Sequoia and Kings Canyon National Parks and study co-author. “One of our goals is to reduce risks of undesirable wildfire using prescribed fire. Maybe prescribed fire can also help prepare these forests for a drier future.”
The study was conducted by researchers from and funded by the USGS Western Ecological Research Center and the Sequoia and Kings Canyon National Parks, with operational support from the National Park Service and the Southwest Climate Science Center, which is managed by the USGS National Climate Change and Wildlife Science Center.