Population assessment of arrow-leaf thelypody (Thelypodium eucosmum)

EXECUTIVE SUMMARY
We monitored 21 sites occurring on Prineville BLM lands in 2016, including 2 previously undocumented sites and 9 sites that had been monitored in 2015. Highlights from 2016 were:
• Identified 2 previously undocumented populations
• Plant counts/estimates revealed 44,024 individuals, and ranged from 12 to 29,249
o In 2015, plant counts/estimates revealed only 4,821 individuals, and ranged from 33 to 1,690
o 7 or 9 sites re-monitored from 2015 had higher plant counts in 2016
• Multiple Thelypodium eucosmum specimens were collected that show multiple rosettes/plants arising from a single rootstock
• Seed were collected from throughout the range of the known populations for deposition and long-term storage in the Rae Selling Berry Seed Bank
• We established transects for measuring plant density at Site 133
o Will allow more rapid and consistent assessment by BLM in future
o Density estimates of 29,863 are the highest recorded
– Previous high was 11,000 in 2005
– 2016 estimate includes only density transects, excluding the 2,540 plants recorded in a separate polygon at the site (32,403 total)
o 20 reproductive plants in the ungrazed and grazed (40 total) area of Site 133 were tagged to be re-monitored in 2016 to determine if they die after flowering