Date of this Version
Fire Science Brief, Issue 60, July 2009
Umpqua gentian is an imperiled plant of the gaps and forested places, growing from the central western Cascade Mountains of Oregon, south to the Klamath Mountains in northwestern California. Since 1993, the Bureau of Land Management (BLM) and the Forest Service have worked together on a conservation strategy for this rare species, with the goal of maintaining viable, stable populations of genetic diversity. On the Medford District of the BLM, three sites had been monitored each year since 1995. When the 2002 Biscuit Fire burned the area, scientists had no information on how burning would affect this species. The Biscuit Fire burned in a patchy mosaic—hotter, with more intensity in some places, and lighter, with less intensity in others. The amount of fuel—dead plants—was directly related to how hot an area burned. Factors such as microclimates, local topography and moisture also played a role. Umpqua gentian plants were burned with low intensity fire, high intensity, or remained unburned. One year after the fi re, plants in burned areas were either killed, dormant, or smaller in size than those in undisturbed areas. Plants that suffered moderate to high intensity burns died in higher numbers, or were forced into dormancy. Plants that were lightly burned were damaged, had their size reduced, but survived. The number of plants declined, and population loss was related to amount of area burned. Two to three years after the fire, plants rebounded, and regrew to nearly the size of unburned plants. Populations in burned areas also recovered to pre-burn numbers. Flowering, a periodic, every-other-year occurrence, had not yet recovered, even three years after the fire. The negative effects of fire on flowering plants may have long lasting consequences.