Poster Session I
Project Type
Poster
Project Funding and Affiliations
Montana Space Grant Consortium
Faculty Mentor’s Full Name
Justin Gay (primary), Meredith Zettlemoyer (secondary)
Faculty Mentor’s Department
College of Forestry (Justin Gay), Division of Biological Sciences (Meredith Zettlemoyer)
Additional Mentor
meredith.zettlemoyer@mso.umt.edu
Abstract / Artist's Statement
Over the past century, wildfires have become more frequent and severe across North America's conifer forests. Although high-severity fire is ecologically integral to subalpine lodgepole pine ecosystems, shortened fire return intervals, compared to historical variability, have altered vegetation structure and composition. This has been well documented, as have many other aboveground ecological processes, including those related to carbon pools. However, the effect of shortening intervals on belowground processes and pools, such as pyrogenic carbon (PyC), is poorly understood. While repeated fire is generally associated with declines in soil organic C, responses of pyrogenic carbon (PyC)—a thermally transformed and decomposition-resistant C form—have received limited field investigation. PyC is important for long-term C storage and influences microbial activity and nutrient cycling, yet it remains unclear whether recurrent fire promotes its production or consumption. To evaluate PyC’s response to changing wildfire frequency, we quantified surface mineral soil PyC in burned and unburned plots spanning fire return intervals of 11, 21, and >100 years, and time since last fire of 3 and 15 years, in the Sapphire Mountains of Montana. Our findings revealed that surface PyC pools were lowest in the shortest-interval sites. However, we observed a significant interaction between fire frequency and time since fire. Three years post-fire, PyC did not differ among treatments, whereas after 15 years, all intervals except for the short-interval accumulated PyC. These results suggest PyC is relatively resistant to combustion losses, but also sensitive to post-fire redistribution processes, such as erosion or lateral transport, following repeated burning.
Category
Life Sciences
Soil Pyrogenic Carbon Response and Redistribution under Shortening Wildfire Intervals
UC South Ballroom
Over the past century, wildfires have become more frequent and severe across North America's conifer forests. Although high-severity fire is ecologically integral to subalpine lodgepole pine ecosystems, shortened fire return intervals, compared to historical variability, have altered vegetation structure and composition. This has been well documented, as have many other aboveground ecological processes, including those related to carbon pools. However, the effect of shortening intervals on belowground processes and pools, such as pyrogenic carbon (PyC), is poorly understood. While repeated fire is generally associated with declines in soil organic C, responses of pyrogenic carbon (PyC)—a thermally transformed and decomposition-resistant C form—have received limited field investigation. PyC is important for long-term C storage and influences microbial activity and nutrient cycling, yet it remains unclear whether recurrent fire promotes its production or consumption. To evaluate PyC’s response to changing wildfire frequency, we quantified surface mineral soil PyC in burned and unburned plots spanning fire return intervals of 11, 21, and >100 years, and time since last fire of 3 and 15 years, in the Sapphire Mountains of Montana. Our findings revealed that surface PyC pools were lowest in the shortest-interval sites. However, we observed a significant interaction between fire frequency and time since fire. Three years post-fire, PyC did not differ among treatments, whereas after 15 years, all intervals except for the short-interval accumulated PyC. These results suggest PyC is relatively resistant to combustion losses, but also sensitive to post-fire redistribution processes, such as erosion or lateral transport, following repeated burning.