Designing models to show how soil heating affects microbial processes
The Fire and Dryland Ecosystem Lab, led by Erin Hanan, associate professor of fire and ecosystem ecology, is investigating how soil heating influences soil microbial processes.
The research is funded through a USDA NIFA grant and is being conducted in collaboration with Jessica Miesel (University of Idaho), Matt Dickinson (US Forest Service) and Indrek Whickham (Michigan State University). The team designed a novel burn table experiment to measure soil heating across a range of depths, fuel loading, parent material and soil moisture in a factorial design. This experiment was led by doctoral student Elena Cox at the University of Nevada, Reno.
Elena collected soils derived from two distinct parent materials in the Sierra Nevada:
- Decomposed granite soils were collected from Whittell Forest
- Andesite soils were collected from the Sagehen Experiment Forest
They filled calorimeters with soils collected from the two sites and layered duff and litter (also collected from Whittell) on the table above the calorimeters to represent moderate and high surface fuel loading. In each calorimeter, they installed temperature sensors at multiple depths. They estimated flame temperatures using temperature-sensitive paints, thermal imaging at the location of each calorimeter using an FLIR camera, and radiant energy from the surface using a radiometer. Following the burn, they estimated soil microbial biomass, respiration and extracellular enzyme activity at multiple depths in each soil profile. They are also quantifying total and exchangeable organic carbon and nitrogen, and fungal to bacterial ratios.
This research is expected to yield several publications and will contribute to advancing the Soil Heating In Fire Model (SheFire) developed in the Hanan lab in a prior project led by master’s student Mary Brady.