Assessing Management Techniques for Lomatium Cookii (Cook’s desert-parsley)

EXECUTIVE SUMMARY
This document summarizes results from two studies involving habitat management techniques for L. cookii to support recovery of the species. The studies include 1) an evaluation of herbicide effects at Illinois Forks State Park, and 2) the effects of prescribed fire on L. cookii and the surrounding plant community at French Flat Middle and French Flat South.
Illinois Forks
There were no clear differences in survivorship or size of L. cookii by treatment at Illinois Forks State Park in 2015 or 2016 (one year and two years post-treatment). There were changes in the plant community observed from 2014-2016, however treatment effects were not significant.
French Flat
Density (and population size) of L. cookii at French Flat Middle and French Flat South in 2014 and 2015 have been among the lowest recorded at these sites since monitoring began in 1993. While the cause of this decline is unclear, competition with non-native species, increasing litter and thatch, disturbance by off-road vehicles and climatic factors may be playing a role. In the fall of 2015, approximately half of the occupied portion of each meadow was burned under the supervision of BLM staff.
In the first year post-burn there were no differences in population structure (proportion of individuals in each size class) between the burned and unburned portions of the habitat. At French Flat Middle a larger proportion of the plants were grazed in the burned than unburned portions of the population (49% vs. 29%). At both French Flat Middle and French Flat South, the density of plants in the burned portion was slightly lower (7.9 and 9.1 plants per m2) than that of the unburned portion (12.6 and 13.9 plants per m2), however the difference was not significant. Results in 2017 are expected to be more informative, particularly if there are differences in recruitment, or other changes in population structure that were not immediately evident.
The cover of invasive graminoids is so low in the portions occupied by L. cookii that differences between burned and unburned portions were negligible. In burned plots there was higher cover of bareground and gravel than in unburned portions. Native graminoid cover was lower in burned plots, due to decreases in the size of Danthonia unispicata bunches.