ARS | Publication request: Evaluating the impact of Wyoming big sagebrush fuel loads on bunchgrass mortality following a fire event

Submitted to: Society for Range Management Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: September 25, 2012
Publication Date: February 25, 2013
Citation: Hulet, A., Boyd, C.S., Svejcar, A.J. 2013. Evaluating the impact of Wyoming big sagebrush fuel loads on bunchgrass mortality following a fire event [abstract]. 66th Annual Meeting of the Society for Range Management, February 3-7, 2013, Oklahoma City, Oklahoma. Paper No. 287.

Technical Abstract: Fire temperatures can vary spatially due to fuel loading characteristics and burn conditions. The influence of fuel loads, particularly that of sagebrush, on bunchgrass mortality following a wildfire is largely unknown. In this study, we quantified pre-burn shrub fuel loads and its impact on bluebunch wheatgrass and Idaho fescue mortality. We used a randomized complete block design with varying amounts of shrub fuel loads per plot. Within each plot and for each bunchgrass species, two locations relative to sagebrush plants were selected: one within a sagebrush canopy and one in an interspace. Each bunchgrass was instrumented with four, type-K thermocouples immediately before the burn at the following locations: 2cm below the soil surface, at the growing point in the center of the plant, at the growing point within 2 cm of the edge of the plant, and 8-10 cm above the soil surface in the center of the plant. Preliminary results suggest that bunchgrass plants within sagebrush canopies were exposed to lethal temperatures (>50° C) longer than bunchgrass plants found in the interspace. Plots with greater sagebrush fuel loads, were more likely to create fire conditions severe enough to kill bunchgrass plants both within shrub canopies as well as interspace plants. As we increase our understanding regarding the influence of Wyoming big sagebrush on bunchgrass mortality, we can better prioritize fire rehabilitation efforts and identify communities where pre-emptive restoration practices can be implemented.