Yosemite Forest questions long-term effects of wildfires

Researcher Jim Lutz stands next to a smoldering log

In September 2013, the Rim Fire – a wildfire that began from an illegal campfire in the Sierra Nevada Mountains - burned through 1,041  sq. kms. of the Yosemite National Park, including the Yosemite Forest Dynamics Plot (YFDP). While the entire plot burned, most of the plot was spared the full force of the wildfire, burning at intensities lower than needed to kill the larger trees.  However, many trees did die.  Patches of the forest remained unburned yet some patches had considerable tree mortality. Estimates are that about 12,000 out of a total of 36,000 trees being monitored since 2009 died in the fire – mostly trees less than 10 cm in diameter.

How will this effect research at YFDP? Researchers will re-measure the plot this May, prior to the 2014 growing season to record exactly what changes the fire caused. The team will record changes in diameter of trees since the plot was established, as well as the way fire killed trees.  They will also measure changes in surface fuels and in the cover of low shrubs. Gathering this fire-related information will help answer important questions such as:, what were the relationships between trees, fuel accumulation, and tree death? How does fire affect biodiversity?  How does fire change the structure of the forest used by birds and mammals?  YFDP researchers already perform annual mortality checks, so they will be able to monitor the long terms effects of the fire as well as the immediate effects of forest changes. The results should provide a unique understanding of how fire affects these old-growth forests.

Larger trees mostly survived

During the fire the research team worked with park fire and resource managers to provide assistance with fire planning and safeguarding park resources. The YFDP research team works with Yosemite National Park on a variety of science and management issues. This summer, the re-measurement will be carried out by a core team of four technicians - all with previous experience in the western ForestGEO plots - as well students from Utah State University, University of Montana, Washington State University, and University of Washington. Volunteers will also play a key role – just as they have in every year since 2009. The broad mission of this project is to build a science-based management of Yosemite forests through long-term research and capacity strengthening.

YFDP Research Team: Jim Lutz (Utah State University), Andrew Larson (University of Montana), Mark Swanson (Washington State University), and James Freund (University of Washington).

Click here to learn more about Yosemite Forest Dynamics Plot.