Threat assessment for Limnanthes pumila ssp. pumila (dwarf woolly meadowfoam) on Table Rocks ACEC

EXECUTIVE SUMMARY
Upper and Lower Table Rocks, located northeast of Medford, Oregon, are collectively designated as an Area of Critical Environmental Concern (ACEC) by the Bureau of Land Management (BLM). The Table Rocks are characterized primarily by vernal pool and mound habitats that support several rare species.
Since 2006, the Institute for Applied Ecology (IAE) has monitored experimental plots to determine population trends and the effects of grazing, trampling, and invasive species on L. pumila ssp. pumila, and used transects to document plant community types, disturbances (including trails and animals activity), and distribution of habitat types. In 2017, we monitored L. pumila ssp. pumila populations and focus discussion on population trends of L. pumila ssp. pumila on Upper and Lower Table Rocks.

Limnanthes pumila ssp. pumila
• Following a steady decline from 2010 to 2012, number of L. pumila ssp. pumila in long-term monitoring plots on Lower Table Rock have fluctuated over the years. While 2015 had the lowest number of L. pumila ssp. pumila observed over the course of this study, we recorded increases in the number of plants over the last two years.
• In 2017, we again observed fewer plants in high traffic areas than in moderate traffic areas, but there was not a significant difference as there was in 2016.
• Upper Table Rock had trends similar to those observed on Lower Table Rock – 2015 had the lowest numbers over the course of this study, but there have been increases in number of plants and number of flowers per plant over the last two years.
• In 2017, mean number of plants and number of flowers per plant did not differ significantly between moderate traffic and high traffic plots. Continued monitoring of these plots over time will allow us to compare impacts of recreation traffic on the heavily used portion of Upper Table Rock.

Community monitoring of the fire retardant drop
• From 2013 to 2016 we observed a decline in non-native grasses both within and outside of the fire retardant drop; over the past two years of sampling, non-native grass cover has remained stable. After low numbers in 2015, we observed an increase in L. pumila ssp. pumila in 2016, followed by a decrease in 2017. Pool habitats declined from 2014 to 2015, but increased in 2016 and 2017.
• Long-term monitoring plots were used to assess impacts of the prescribed fire that occurred in the area of the fire retardant drop in fall 2015. Mean number of plants and number of flowers per plant did not differ between burned and unburned plots in 2017. Litter cover was similar in burned plots and unburned plots. These results should be interpreted cautiously as plots were not set up to monitor fire effects.