. The Canadian field-naturalist. Natural history; Sciences naturelles. 338 The Canadian Field-Naturalist Vol. 120 nopodium subglahnim populations are found in the Routledge (White and Johnson 1980; Robson et al. 2005) and Brandon (Carberry) Sand Hills. Due to the annual nature of this species, the popula- tion numbers fluctuate widely. Data collected in 2004- 2005 supports this hypothesis. At several Saskatche- wan locations fewer than 50 individuals were found in the late 1990s but several hundred were observed in 2004. In the Routledge Sand Hills of Manitoba, 19 plants were observed in 2004
. The Canadian field-naturalist. Natural history; Sciences naturelles. 338 The Canadian Field-Naturalist Vol. 120 nopodium subglahnim populations are found in the Routledge (White and Johnson 1980; Robson et al. 2005) and Brandon (Carberry) Sand Hills. Due to the annual nature of this species, the popula- tion numbers fluctuate widely. Data collected in 2004- 2005 supports this hypothesis. At several Saskatche- wan locations fewer than 50 individuals were found in the late 1990s but several hundred were observed in 2004. In the Routledge Sand Hills of Manitoba, 19 plants were observed in 2004 but 68 were seen in 2005. Population fluctuations, possibly in response to cli- mate, make it difficult to accurately estimate the num- ber of plants and the vulnerability of populations. In 2004 there were an estimated 8400 plants growing in Canada; in other years only a few hundred to several thousand plants were observed. However, even though plants may not be growing at a site in a given year, seeds are likely present in the seed bank. The largest populations occur in the Great and Seward Sand Hills of Saskatchewan, and in the Grassy Lake Sand Hills of Alberta. Based on the observed fluctuations in population size and recognition that at any given year there are some C. subglabrum seeds dormant in the seed bank, there are likely between 5 000 and 10 000 plants in Canada. The following is an overview of populations in the three provinces of occurrence. Alberta The only Alberta site visited recently (in 2004) was Lost River. Most population research on C. subglabrum in Alberta was conducted in the late 1980s (Table 2). Since such a long time has passed since these sites were visited, the dunes may have stabilized further, reducing available habitat. Saskatchewan Extensive C. subglabrum survey work was done in the mid to late 1990s in the sand hills of Saskatchewan (Robson 1997a; Lamont and Gerry 1998*). Since the. Figure 2. Distribution of Chenopodium subglabrum in North Amer
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