Large Downed Wood as Post-fire Refugia for Terrestrial Salamanders in Pacific Northwest Forests
September 2020 - August 2023
- US Geological Survey
Downed wood on the forest floor does more than provide habitat for amphibians, reptiles, birds and mammals. These decomposing habitat structures modify the temperature and moisture conditions in the forest itself. Inside and around downed wood, local climate conditions, or microclimates, provide wildlife with stable habitats that allow for persistence during and after wildfires. Cooler, wetter microclimates buffer the effects of wildfire in Oregon’s forests, making microclimate an important component of forest management. Despite the significance of downed wood to forest ecosystem function, forest management practices require only two downed logs to be retained for every acre harvested. To better inform forest management and species conservation efforts, it is vital that we better understand the role of downed wood in post-fire recovery of forest-dependent species. We propose a three-year study that explores the relationship between downed wood, microclimate, and wildfire on terrestrial salamander diversity. Terrestrial salamanders are sensitive to environmental change, dependent on moist habitats, and are strongly associated with downed wood. We will compare salamander diversity and abundance in forests that vary in time since fire in forests across western Oregon, capturing the inherent climate variation from the moist northern end to the drier southern end of the state. We will relate salamander presence and abundance with microclimates associated with downed wood, expecting to find more salamanders, including rare and threatened species, in forests with cooler, wetter microclimates. In areas with recent, high severity fire, we expect downed wood to facilitate salamander persistence, particularly in the drier forests of southern Oregon. This research will provide managers with important information on the quantity and quality of downed wood needed to maintain microclimate conditions that can protect and buffer forests from the ever-increasing threat of climate-driven wildfires.