The ability of winter grazing to reduce wildfire size, intensity, and fire-induced plant mortality was not demonstrated: a comment on Davies et al. (2015)

Authors: SMITH, ALISTAIR - University Of Idaho; TALHELM, ALAN - University Of Idaho; KOLDEN, CRYSTAL - University Of Idaho; Newingham, Beth; KREMENS, ROBERT - Rochester Institute Of Technology; ADAMS, HENRY - Oklahoma State University; COHEN, JACK - Us Forest Service (FS); YEDINAK, KARA - University Of Idaho

Submitted to: International Journal of Wildland Fire
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/15/2015
Publication Date: 3/3/2016
Citation: Smith, A.M., Talhelm, A.F., Kolden, C.A., Newingham, B.A., Kremens, R.L., Adams, H.D., Cohen, J.D., Yedinak, K.M. 2016. The ability of winter grazing to reduce wildfire size, intensity, and fire-induced plant mortality was not demonstrated: a comment on Davies et al. (2015). International Journal of Wildland Fire. doi: 10.1071/WF15163

Interpretive Summary: As wildfire size and frequency increases in the western US, land management options are needed to reduce the impacts of megafires, including rangeland fires in the Great Basin. Potential management tools include grazing, fuel breaks, and biological or chemical control of annual invasive grasses. We reviewed a study examining the potential use of winter grazing to reduce fire size, intensity, and behavior. We found that the study could be improved by better methodology and less extrapolation of results and management recommendations. Of primary importance was the incorrect scientific methodology used to measure fire behavior characteristics. This illustrates the importance of using interdisciplinary research teams, including fire behavior scientists, to conduct research on complicated issues, such as fuel management.

Technical Abstract: A recent study by Davies et al. sought to test whether winter grazing could reduce wildfire size, fire behavior and intensity metrics, and fire-induced plant mortality in shrub-grasslands. The authors concluded that ungrazed rangelands may experience fire-induced mortality of native perennial bunchgrasses. The authors also presented several statements regarding the benefits of winter grazing on post-fire plant community responses. However, we contend that the study by Davies et al. has underlying methodological errors, lacks data necessary to support their conclusions, and does not provide a thorough discussion on the effect of grazing on rangeland ecosystems. Importantly, Davies et al. presented no data on the post-fire mortality of the perennial bunchgrasses or on the changes in plant community composition following their experimental fires. Rather, Davies et al. inferred these conclusions based on their observed fire behavior metrics of maximum temperature and a term described as the “heat load”. however, we propose neither metric is appropriate for describing the heat flux impacts on plants. This lack of post-fire data, several methodological errors, and the use of unproven thermal metrics limits the authors’ ability to support their stated conclusions.