Effects of Wildfires on Antelope Bitterbrush populations

Authors: Clements, Darin

Submitted to: The Progressive Rancher
Publication Type: Popular Publication
Publication Acceptance Date: 3/19/2025
Publication Date: 4/7/2025
Citation: Clements, D.D. 2025. Effects of Wildfires on Antelope Bitterbrush populations. The Progressive Rancher. 25(4):23-25.

Interpretive Summary:

Technical Abstract: One of the most influential factors on antelope bitterbrush population dynamics is fire. Rangelands dominated by woody vegetation suggest the absence of fire, whereas dominance by herbaceous vegetation suggests the presence of fire. Wildfires are a natural feature of the environment. For more than a century and a half, human interference with fire and other natural processes has greatly influenced western rangelands. Plant communities always reflect their species composition, spatial distribution, and demography how the previous plant community that occupied the site was destroyed. This is known as the stand renewal process. If the stand renewal process has been consistently catastrophic over-time the natural plant community will have evolved under selection pressure associated with characteristics of the stand renewal process. Seed germination and seedling establishment will be adapted to the stand renewal process or a vegetative process; stem, root crown, or root sprouting will have been selected to renew the stand. Fire plays a crucial role in the seed and seedbed ecology of antelope bitterbrush. The timing of wildfires is of particular importance, as are the conditions of the year that the fire occurs. In some years, antelope bitterbrush seed production may be low or non-existent because of late frost, insect outbreaks, excessive browsing, severe droughts or a combination of these occurrences. Because the seed banks of antelope bitterbrush are controlled by granivorous rodents, there may be no seed reserves available if the stand burns during a poor seed production year. Also, if the stand burns while the seed crop is still on the plant, all is lost. Because the timing of wildfires is critical in the seed and seedbed dynamics of antelope bitterbrush, anything that affects wildfire timing also affects antelope bitterbrush survival. The accidental introduction of cheatgrass increased the chance, rate, spread and season of wildfires throughout the Intermountain west. The fine-textured early maturing cheatgrass herbage dries six weeks to two months prior to native perennial bunchgrasses, and in years when cheatgrass is abundant, the chances of ignition and rapid spread of wildfires are greatly enhanced. The change in the season of wildfires to early summer is catastrophic to antelope bitterbrush stands. In the nearly four decades of researching and managing antelope bitterbrush in norther Nevada and northeastern California, the U.S.D.A. Agricultural Research Service, Great Basin Rangelands Research Unit has reported the average level of resprouting of antelope bitterbrush following wildfires at 13%, far too low to sustain an antelope bitterbrush population. The problem resource managers have faced in the past and continue to face are the many variables that play a role in fire-bitterbrush relations. As traditional wildlife management has preached, no two environments are alike, and each environment must learn to distinguish between fire characteristics that are destructive to antelope bitterbrush ecology and those that compliment antelope bitterbrush ecology. Following wildfire disturbance, the direct seeding or transplanting of antelope bitterbush will most likely be necessary to sustain and enhance antelope bitterbrush populations.