Overgrown forests, however, and can increase the risk of more intense forest fires spreading much faster. Thinning these forests by cutting down excess trees and burning underbrush with controlled fires is critical to keeping forest from fueling potential wildfires.
A new study led by the University of Washington, the University of California, Davis, and the USDA Forest Service Pacific Southwest Research Station suggests that thinning forest canopies may not harm spotted owls. Cover in tall trees, the study claimed, is a central requirement for spotted owl, not total canopy cover. The study claims that spotted owls typically avoid cover created by stands of shorter trees. Malcolm North, a research forest ecologist with UC Davis’ John Muir Institute of the Environment and the study’s lead author, believes that this discovery could lead to protecting large tree habitats while preserving the owls’s habitat.
Previous studies concluded that spotted owls disproportionately thrived in forests with 70 percent or higher tree canopy cover — which largely governed old habitat protection guidelines. These studies, however, did not distinguish the value of tall trees or high canopy cover to spotted owl populations. Using airborne laser pulses from Light Detection and Ranging imaging, UW scientists measured a forest’s canopy in detail, measuring the height, distribution, and gaps in tree foliage across 1.2 million acres of the Sierra Nevada forests in California.
Team members used a data set amassed by wildlife scientists spanning over two decades that recorded the locations of 316 owl nests in three national forests and Sequoia and Kings Canyon national parks. Spotted owls, the team found, sought out forests with disproportionately high concentrations of tall trees measuring at least 105 feet tall, but ideally taller than 157 feet. These tall trees also tended to be areas with high levels of canopy cover. However, the spotted owls expressed no preference to wooded areas with dense canopy cover, from medium-height trees and avoided areas with high cover in trees less than 52 feet tall.
The team hopes that this new study helps change not only our perception of what spotted owls need most, but allow forest rangers to better manage forest overgrowth without having to harm local wildlife.
Sources: A Win-Win for Spotted Owls and Forest Management https://www.ucdavis.edu/news/win-win-spotted-owls-and-forest-management https://www.nationalforests.org/blog/why-thinning-helps-the-forest