Table 4 
Mean monthly air temperatures (°C) for summer months and growing degrees 
accumulated above daily mean of 0 C for phytometer growing periods at Palmer 
and Prudhoe in 1972 and 1973. * 
Monthly Means 
Location & Year June July 
Prudhoe 
1972 21° 6.7 
1973 2.6 7.8 
Palmer 
1972 10.9 15.5 
1973 11.6 13.8 
Phytometer 
Growing Period 
No. Growing 
Aug. Days Degrees 
6.4 76 447 
13 65 473 
13.4 76 1063 
11.6 66 852 
Monthly means and growing degrees were based on daily means derived from daily maxima and minima obtained at 
about 2 m above the ground. The Prudhoe data were furnished by the Atlantic Richfield Co. from readings taken at their 
base camp in the Prudhoe Bay region. 
** In all cases except June, 1972 at Prudhoe the monthly mean temperature also equaled the mean number of growing 
degrees for the month. The average number of growing degrees for June, 1972 at Prudhoe was 2.3. The lower monthly 
mean temperature was due to 7 days averaging O°C or below. 
Only Sprite pea matured to the stage of seed 
production at Palmer. Annual ryegrass produced 
inflorescences in the emerging to emergent con- 
dition but did not develop beyond the early 
flowering stage. Timothy did not flower. None 
of the species flowered at Prudhoe. 
Acknowledgments 
These studies were jointly funded from the 
Tundra Biome Center, University of Alaska, 
utilizing both State of Alaska and Prudhoe Bay 
Environmental Subcommittee funds. Consider- 
able savings in costs to all projects were accom- 
plished by combining our Prudhoe schedules 
with non-Biome sponsored research at Prudhoe. 
The alpine plant materials from Colorado were 
kindly furnished by Erik K. Bonde and Maxine 
F. Foreman, who are conducting a similar study 
along an altitudinal transect in Colorado. 
References 
Billings, W. D., P. J. Godfrey, B. F. Chabot, and 
D. P. Bourque (1971). Metabolic acclimation 
to temperature in arctic and alpine ecotypes 
of Oxyria digyna. Arct. and Alp. Res., 
3:277-289. 
Bocher, T. W. (1963). Phytogeography of mid- 
dle west Greenland. Meddele/ser Om Gron- 
land, 148:1-289. 
Bradshaw, A. D. (1959). Population differen- 
tiation in Agrostis tenuis Sibth. |. Morpho- 
logical differentiation. New Phyt., 
58:208-227. 
Clausen, J., D.D. Keck, and W.M. Hiesey 
(1970). Experimental studies on the nature 
of species. I. Effect of varied environments 
on western North American plants. Carnegie 
Inst. of Washington, Pub. No. 520, 452 pp. 
Conkle, M. T. (1973). Growth data for 29 years 
from the California elevational transect 
study of ponderosa pine. Forest Sci., 
19:31-39. 
Mark, A. F. (1965). Ecotypic differentiation in 
Otago populations of narrow-leaved snow 
tussock Chionochloa rigida. New Zealand J. 
Bot., 3:277-299. 
Mosquin, T. (1966). Reproductive specialization 
as a factor in the evolution of the Canadian 
flora. Pages 43-65 in The Evolution of 
Canada’s Flora (R. L. Taylor and R. A. Lud- 
wig, eds.). University of Toronto Press. 
Savile, D. B. O. (1972). Arctic adaptations in 
plants. Canada Dept. Agric., Monog. 
31:1-81. 
