Grand coulee owl-clover (Orthocarpus barbatus) COSEWIC assessment and status report: chapter 9
Population sizes and trends
There are four locations for Orthocarpus barbatus in Canada, all in the southern Okanagan Valley and the southern Similkameen Valley (Figure 3, Table 1). Population numbers range from 185 to 8000 on areas of 22 m2 to 2000 m2. Population trends are not well known. Only one site (Mount Kruger, above the racetrack) has data from more than several years. At this site, a subpopulation had ca. 200, 1200 to 1500, 153 and 222 plants in 1995, 1997, 2003 and 2004, respectively. At the Kilapoola site (Subpopulation 1), plant numbers and the area covered increased by 100% between 2003 and 2004. It may be assumed that these fluctuations are natural and due to the annual nature of the genus. Atsatt (1970) observed that patterns of abundance and distribution in populations of grassland Orthocarpus show sizeable year-to-year fluctuations within sites. Wide population fluctuations are typical in many annual species and such fluctuations may obscure population trends, especially if the increase in shoot numbers occurs through seed bank depletion.
Population | Last Observation | Observers | Number of Plants/Area |
---|---|---|---|
Mt. Kruger, above golf course | 1997 | Lomer | Unknown |
“Veronica Lake” | 2002 | Penny & Donovan | 367/1800 m2 |
Mt. Kruger, above racetrack, Subpopulation 1 | 2004 | Douglas & Smith | 222/22 m2 |
Mt. Kruger, above racetrack, Subpopulation 2 | 2004 | Douglas & Smith | 3000-3500/245 m2 |
KilpoolaLake area, Subpopulation 1 | 2004 | Douglas & Smith | 5000-8000 /2000 m2 |
KilpoolaLake area, Subpopulation 2 | 2004 | Douglas & Smith | 185/57 m2 |
KilpoolaLake area, Subpopulation 3 | 2004 | Douglas & Smith | 300/484 m2 |
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