Population assessment of Pyrrocoma radiata (Snake River goldenweed)

The Institute for Applied Ecology monitored populations of Pyrrocoma radiata (Snake River goldenweed) on land managed by the BLM Vale District in 2015 and 2016.
• We monitored 26 sites occurring on Vale BLM lands in 2015, including 1 previously undocumented site.
o Identified 1 previously undocumented population.
o Counted/estimated 16,368 plants, with sites ranging from 12 to 3109.
o 3 sites were found to have no plants in 2015.
• We monitored 50 sites occurring on Vale BLM lands in 2016, including 3 sites that had been monitored in 2015. In addition, 2 new populations of P. radiata were documented by Roger Ferriel, Vale District BLM Fire Botanist, in 2016.
o Counted/estimated 74,290 plants, with sites ranging from 2 to 35,000.
o 10 sites were found to have no plants in 2016.
o 3 sites re-monitored from 2015 had higher plant counts in 2016.
• We revisited 5 paired (fenced and unfenced) long-term study plots in 2015 that had been established in 1991.
o In 2015, the Upper Lime site had the highest total number of plants (586 plants) compared to the 4 other long-term monitoring sites (279 plants total), with the lowest being the Lower Lime site, which only had a single vegetative plant.
o In 2015 the average plant height was greater in the “OUT” plots at all sites, except for Upper Lookout Mountain.
– Upper Lookout Mtn “IN” had the largest plants with the highest proportion of seed/flower heads per plant of any of the sites in 2015.
o In 2015, overall P. radiata cover in several long-term study plots (Upper Lime “IN”, Lower Lime “IN”, and Upper Lookout Mtn “OUT”) had decreased from 2009.
o Cover of exotic graminoids increased in all long-term study plots from 1991 to 2015.