Data for: Viability of multiple populations across the range of a species at risk: the case of Pitcher's Thistle, Cirsium pitcheri, in Canada

Three populations at Pukaskwa National Park (Ontario, Canada) were surveyed annually between 1982 and 2015, and an additional 33 populations on Lake Huron were monitored annually between 2000 and 2017, with methods standardized in 2004. Monitoring at each location consisted in recording the total number of plants by life stage (i.e., seedling, rosette, or mature/flowering). The data here are for number of rosettes only. One sheet contains the survey data for each population, another sheet contains information on the population locations and the area surveyed in each.