Question: Grasses often resprout from surviving belowground buds following a fire in which aboveground matter is consumed. We used a soil heat and water transport model to present a general method for determining the potential mortality of rhizome buds due to fire for three tallgrass species (Andropogon gerardii, Sorghastrum nutans, and Panicum virgatum).
Methods: Soil heating was described by physical processes that include heat conduction through the soil and heating and evaporation of soil water. We considered the following factors: soil moisture, texture, mineral thermal conductivity, maximum surface temperature, and fire residence time. Simulated soil temperature profiles were combined with measured belowground bud distributions to determine the proportion of buds expected to be heated to lethal temperatures under various conditions.
Location: Wisconsin, USA.
Results: Lethal temperatures for buds do not occur below ∼2 cm, and at least 30% of rhizome buds remain below lethal temperatures, even under extreme conditions.
Conclusions: The model explains the possible mechanisms for grass belowground rhizome bud survival in fires. Changes in fire and soil conditions do not notably impact soil temperatures and rhizome bud survival.