Yellow montane violet (Viola praemorsa) COSEWIC assessment and status report: chapter 7

Population Sizes and Trends

Search effort

Suitable sites have been surveyed repeatedly since the early 1980s in a series of projects designed to document the distribution of rare plants of Garry oak woodlands and maritime meadows on southeast Vancouver Island and the southern Gulf Islands. The principal investigators included Adolf and Oldriska Ceska, Matt Fairbarns, Hans Roemer, Jenifer Penny, Harvey Janszen, Frank Lomer and the late George Douglas, all of whom are/were familiar with the yellow montane violet. These investigators have examined a number of areas beyond the documented range of yellow montane violet but failed to document any significant range extensions.

Over 90 sites with Garry oak woodlands and maritime meadows have been investigated (Figure 4) and much of it has been surveyed more than once during this period. During the past decade alone, over 500 person-days have been spent searching for rare species in suitable habitats. Despite the concentrated effort, only one new population of yellow montane violet has been discovered, since 1997 (Duncan 4). Private lands and Indian reserves, which only constitute a small proportion of the apparently suitable habitat, have not been surveyed as thoroughly as public lands.

Figure 4. Search effort for yellow montane violet, 2001-2006.

Figure 4. Search effort for yellow montane violet, 2001-2006

Abundance

In the absence of information on rates of genetic exchange, occurrences of yellow montane violet more than 1,000 m apart are treated as separate locations. On this basis, it has been validly1 reported from 18-19 locations in British Columbia (Table 1). The uncertainty lies in the fact that the populations at Saanich 3 and Saanich 6 are too vaguely reported to determine if they were more than 1,000 m apart (both appear to be extirpated). Fourteen populations are extant. Some populations consist of multiple subpopulations (i.e. patches separated by <1,000 m).

Table 1. Localities, population and land ownership for yellow montane violet
[Table 1 cites first record, most recent observation, any other observations with reliable population estimates and (where applicable) subsequent unsuccessful surveys.]
Location Year Collector/observer Number of plants/area Land ownership/notes
Victoria 1897 Henry unknown location too vague
Victoria 1

1913

1993

1994

1997

2006

Macoun

Douglas

Douglas

Douglas

Fairbarns

unknown

400-450/1,100 m²

100-150/50 m²

465/1,000 m²

885/525 m²

municipal park
Victoria 2

1972

1993

1994

1997

2006

Roemer

Douglas

Ryan & Douglas

Douglas

Fairbarns

unknown

unknown

500/?

490/435

304/2,500 m²

municipal park
Oak Bay 1a

1994

1997

2004

2006

Douglas

Douglas

Fairbarns

Fairbarns

125/18 m²

95/18 m²

25-30/6 m²

41/8 m²

municipal park
Oak Bay 1b

2004

2006

Fairbarns & Penny

Fairbarns

10/5 m²

2/6 m²

municipal park
Oak Bay 2

1963

1993

2003

2006

Young

Ryan and Douglas

Ceska and Ceska

Fairbarns

unknown

failed to find

failed to find

failed to find

municipal park
Saanich 1

1971

1995

2001

Roemer

Lee

Penny

unknown

2/1 m²

86/<100 m²

municipal park
Saanich 2

1997

2000

2006

Roemer

Douglas

Fairbarns

unknown

282/305 m²

297+/- 20/1,874 m²

municipal park
Saanich 3 1887 Macoun unknown unknown
Saanich 4

1994

1996

1997

1999

2000

2001

2002

2006

2006

Ryan

Mothersill

Douglas

Mothersill

Mothersill

Mothersill

Mothersill

Fairbarns

Roemer

40/27 m²

20/2 m²

59/10 m²

12/?

15/?

17/?

17/?

7/20 m²

7/5 m²

municipal park
Saanich 5

1997

2000

2001

2006

Fraser

Fraser

Fraser

Fairbarns

111

66

78/10 m²

56/12 m²

regional park
Saanich 6 1947 Unknown unknown unknown
Saanich 7

1919

2003

2005

Newcombe

Fairbarns & Roemer

Fairbarns

unknown

1/27 m²

3/27 m²

private property
Saanich 8

1964

1987

1995

2001

Hett

Ring

Golinksi

Hartwell

unknown

unknown

failed to find

failed to find

 
Duncan 1

1993

1994

1997

2006

Douglas

Douglas

Douglas

Fairbarns

unknown

25/100 m²

56/120 m²

33/50 m²

ecological reserve
Duncan 2

1933

1997

1998

2000

2006

Newcombe

Douglas

Douglas

Douglas

MacDougall

unknown

>6,400/1,000 m²

6,940/?

3,205/12,373 m²

1,736 +/-100/?

NGO conservation reserve
Duncan 3

1992

1993

1997

2003

2004

2005

2006

2007

Ceska

Douglas

Douglas

Roemer and Fairbarns

Roemer and Fairbarns

Roemer and Fleming

Roemer and Fleming

Fleming

unknown

unknown

45,000/5,700 m²

10,000

28,700/4,320 m²

16,300/3,100 m²

10,700/2,350 m²

20,400

NGO conservation reserve
Duncan 4 2004 Douglas and Smith 5/? church
Saltspring 1

1985

2006

Roemer

McIntosh & Linton

unknown

14/100 m²

provincial park
Saltspring 2

1993

1996

1999

2005

2007

Chatwin

Penny

Lomer

Roemer2

Annschild

>300/400 m²

200/2,500 m²

200-300/?

200/50 m²

19,278 plants: 14,096 on Transport Canada lands and 5,182 on provincial crown lands and private lands; population occupies approximately 10 ha

mixed (Transport Canada, provincial crown land and private land)
Nanoose Hill

1976

1973

2005

Douglas

Douglas

Fairbarns

unknown

failed to find

failed to find

private or federal?
Comox

1961

1993

Beamish

Cadrin

unknown

failed to find

regional park?

Table 1 cites first record, most recent observation, any other observations with reliable population estimates and (where applicable) subsequent unsuccessful surveys.

Based on recent data from each of the sites, the total British Columbia population size is between 32,000 and 49,000 plants with approximately 80-90% of the subspecies’ population concentrated in the two largest populations, at Duncan 3 and Saltspring 2.

Fluctuations and trends

The number of populations has been in slow decline – five to six populations have disappeared over the past century but none of these have been lost over the past 10 years. In most cases records are not adequate enough to determine when populations disappeared, but four of the populations appear to have been lost between 1961 and 1995.

Although Victoria 1 and Saltspring 2 appear to be increasing, the change in numbers is actually a result of the discovery of unreported subpopulations and more careful searches of known subpopulations. Anecdotal evidence suggests that the larger populations fluctuate substantially. The best documented fluctuation is at Duncan 3, where numbers have fluctuated between 10,000 and 28,000 (using a constant technique and coordinated observers) from 2003-2007.

There is no clear trend in the extent of the actual area of habitat occupied, probably because of inconsistencies in methods of estimation among observers. The quality of the area of occupancy is declining, primarily as the result of invasion by exotic plants.

Rescue effect

Yellow montane violet is not known from the nearby San Juan Islands(Atkinson and Sharpe 1993, D. Giblin pers. comm. 2006) or the Olympic Peninsula (Buckingham et al. 1995). The nearest population is about 100 km away, near Tacoma, Washington (Burke Museum of Natural History and Culture 2006). The status of the U.S. population of yellow montane violet is uncertain (see “Existing protection or other status”). Given the very limited ability of this species to disperse over distances of more than a few metres, the British Columbia population is very unlikely to be rescued by natural circumstances.

1 The Metchosin record has been rejected as explained in Table 1.

2 Further surveys needed to determine if there are undiscovered subpopulations at this location.

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