Lomatium cookii (Cook's desert parsley), is listed as endangered by the State of Oregon and the U.S. Fish and Wildlife Service. The species is endemic to southwestern Oregon in two population centers, one in Josephine County in the Illinois Valley and one in Jackson County in the Agate Desert north of the Medford Plains. Placer gold mining has restricted the population at French Flat and permanently altered much of the natural hydrologic patterns through the meadows. L. cookii habitat in the Illinois Valley is threatened by rural development and abuse by recreational users in the area. To assess herbicide as a potential tool to control annual grasses and other noxious weeds in the presence of L. cookii, we established plots in fall or early spring of 2014/2015. Treatments included Control, Fluazifop, Glyphosate and Imazapic. To study the effects of fire on L. cookii, portions of the population at French Flat were chosen for an experimental burn treatment in the fall of 2015. Our specific objectives were to: (i) study the effects of herbicide at sites occupied and unoccupied by L. cookii and (ii) study the effects of prescribed fire on L. cookii.
Results/Conclusions
There were no statistically significant differences in survivorship or size of L. cookii among the herbicide treatments for 2 years post-treatment. The plant community response showed interesting patterns, independent of our treatments. Native forbs increased in years 1 and 2 post-treatment across all treatments, including controls, and native graminoids showed a concurrent decrease across all treatments and controls. Invasive, exotic grasses also decreased among all treatments and controls. The decrease in graminoid cover would be expected in the treated plots, but the similar decrease in control plots needs further research and complicates making management recommendations. As expected, prescribed burns decreased litter (6% vs 45%) and increased bareground (57% vs 24%) compared to unburned plots. Native forb cover was not significantly different between burned and unburned, while native graminoid cover was reduced in the burned plots. L. cookii density and size class were not significantly different between burned and unburned. These results show that L. cookii is resilient to the herbicide and fire treatments in our study, but reduction of target species was limited and needs further research.