A classic problem for forest managers has been protecting the habitat for the spotted owl while reducing the fire potential of those forests. A recent lidar survey provided key insights, including tree height and canopy density on how to solve the problem.
The authors also used a data set collected by wildlife researchers spanning more than two decades that recorded the positions of 316 owl nests in three national forests and Sequoia and Kings Canyon national parks.
They found the owls seek out forests with unusually high concentrations of tall trees measuring at least 105 feet tall but preferably taller than 157 feet. These tall trees also tended to be areas with high levels of canopy cover. However, the owls appeared to be indifferent to areas with dense canopy cover from medium-height trees and avoided areas with high cover in short (less than 52 feet tall) trees.
“This could fundamentally resolve the management problem because it would allow for reducing small tree density, through fire and thinning,” said lead author Malcolm North, a research forest ecologist with UC Davis’ John Muir Institute of the Environment and the USDA Pacific Southwest Research Station. “We’ve been losing the large trees, particularly in these extreme wildfire and high drought-mortality events. This is a way to protect more large tree habitat, which is what the owls want, in a way that makes the forest more resilient to these increasing stressors that are becoming more intense with climate change.”