. The Canadian field-naturalist. 1975 Fuller et al.: Natural History of High Arctic Lemmings 229 Table 4—Calorie value (Kcal/g ash-free dry matter) of potential lemming food plants sampled in August 1970 Caloric value Number Species (mean ± SE) of runs Monocots Caiex misandra ± 5 Juncus biglumis ± 3 Liizula nivalis ± 4 Aictagrostis lalifolia ± 2 Caiex stans ± 2 Dicots Salix arctica - entire ± 2 - stems ± 3 CO 1— - leaves ± 5 I Saxifraga oppositifolia ± 5 CD CL < Papaver radicatum ±0
. The Canadian field-naturalist. 1975 Fuller et al.: Natural History of High Arctic Lemmings 229 Table 4—Calorie value (Kcal/g ash-free dry matter) of potential lemming food plants sampled in August 1970 Caloric value Number Species (mean ± SE) of runs Monocots Caiex misandra ± 5 Juncus biglumis ± 3 Liizula nivalis ± 4 Aictagrostis lalifolia ± 2 Caiex stans ± 2 Dicots Salix arctica - entire ± 2 - stems ± 3 CO 1— - leaves ± 5 I Saxifraga oppositifolia ± 5 CD CL < Papaver radicatum ± 3 Dry as integrifolia ± 3 Saxifraga caespitosa ± 5 1- Pedicularis hirsuta ± 2 O o Lichens o Thamnolia vermicidaris ± 4 QC Cetraria nivalis ± 5 LU Cetraria islandica ± 5 I Cladonia puccilum ± 2 ^ Dactylina ramulosa ± 2 < means of Ts recorded daily at 1200 hours (J. Sharp, personal communication). Thickness of snow cover (api) was measured monthly in a meadow adjacent to the Inten- sive Study Site. It increased linearly by 5 cm per month from 10 cm in October 1972 to 30 cm in February 1973, then stabilized at 30 cm through May 1973. Meadows were 50% snow-free on 18 June 1973, the earliest of four years studied. In sharp contrast, 46 cm snow was recorded in the meadow in May and June 1972, and meadows were 50% snow- free only on 6 July—the latest of the years studied. Although no claim can be made that 1972-73 was a "typical" winter, and although the record pertains to a meadow site rather than the transition zone, where most lemming winter nests occur, some observations that have relevance to lemming biology seem war- ranted. By mid-May 1972 Ta already exceeded Tg by about 12°C, and Ts stood at —20°. T^ rose slowly through most of June while the meadow remained snow-covered, then rose 100 50 10 t • rocky outcrops opolygons A meadows ^raise
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