Lomatium cookii population monitoring in the Illinois Valley, Josephine County, Oregon
Lomatium cookii is endemic to southwestern Oregon, and is listed as endangered by the State of Oregon and by the U.S. Fish and Wildlife Service (USFWS). Populations discussed in this
Lomatium cookii is endemic to southwestern Oregon, and is listed as endangered by the State of Oregon and by the U.S. Fish and Wildlife Service (USFWS). Populations discussed in this report are located in the Illinois Valley in Josephine County. Long-term monitoring has occurred at French Flat since 1990, at Rough and Ready since 1994 and at Indian Hill since 1997. Data from these efforts are used to track population dynamics at all sites and create a population viability analysis for French Flat.
French Flat South
- Total population size was estimated at 114,296 individuals in 2013, a 7% decrease since 2012. Average plant density was estimated at 13.0 plants m-2. The proportion of reproductive plants in the overall population was 11%, a 35% decrease since 2012.
- The Population Viability Analysis (PVA) indicated a 98.9% probability this population will decrease 50% in the next 20 years. A catastrophic loss (99% population decrease) over the same period is not likely to occur (< 0.1%).
French Flat Middle
- The total population numbered 81,067 in 2013, a 118% increase since 2012. Density was estimated at 17.3 plants m-2, which was less than the average 23.5 m-2. Reproductive plants composed just over 10% of the overall population, a 60% decrease since 2012.
- The PVA indicated an 82.0% probability this population will decrease 50% in the next 20 years. A catastrophic loss (99%) over the same period is not likely to occur (< 0.1%).
Rough and Ready
- This population decreased 9% to 1,973 plants in 2013. Reproductive adults comprised 34% of the population, a 39% decrease from last year. Barricading with boulders has successfully blocked vehicles from dumping trash in the small meadow and accessing side roads.
- This population increased 13% to 10,543 in 2013. Reproductive adults comprised 24% of the population, a 35% increase since 2012.
Overall, populations of Lomatium cookii in Josephine County have shown increased recruitment of seedlings and population sizes have remained relatively stable. This is likely due in part to active management of these populations by the Medford BLM, including preventing use by off road vehicles. However, population viability analyses indicate there is still risk of serious population declines. Proposed mining activities may have further detrimental impacts on these populations at French Flat. We recommend continued monitoring of these populations to assess population trends, trespass by ORVs, and provide data to assess future impacts to populations from climate change, mining, or other threats.