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

A recent study by Davies et al. sought to test whether winter grazing could reduce wildfire size, fire behaviourand intensity metrics, and fire-induced plant mortality in shrub–grasslands. The authors concluded that ungrazedrangelands may experience fire-induced mortality of native perennial bunchgrasses. The authors also presented severalstatements regarding the benefits of winter grazing on post-fire plant community responses. However, we contend that thestudy by Davies et al. has underlying methodological errors, lacks data necessary to support their conclusions, and does notprovide a thorough discussion on the effect of grazing on rangeland ecosystems. Importantly, Davies et al. presented nodata on the post-fire mortality of the perennial bunchgrasses or on the changes in plant community composition followingtheir experimental fires. Rather, Davies et al. inferred these conclusions based on their observed fire behaviour metrics ofmaximum temperature and a term described as the ‘heat load’. However, we contend that neither metric is appropriate fordescribing the heat flux impacts on plants. This lack of post-fire data, several methodological errors and the use ofinappropriate thermal metrics limit the authors’ ability to support their stated conclusions