264 TRANSACTIONS OF THE 
atures during most of April, the very last part of which 
was marked by freezing temperatures. May was also 
characterized by high temperatures, but with a heavy 
freeze the last of the month which did considerable dam- 
age to tender succulent vegetation. The writer’? has 
recently described the effects of somewhat more severe 
conditions on the growth of Douglas fir in central Utah 
in 1919. From all information at hand this appears to 
be a parallel case, in which the greatly decreased growth 
is due to frost injury the latter part of May, 1914. Doug- 
las fir appears more sensitive to changes in the moisture 
relations of the habitat mainly because of the higher 
moisture requirements of this species; the trees used in 
this study were growing near the lower altitudinal limit 
of Douglas fir and toward the upper limit of western 
yellow pine. The response to the unusually heavy rain- 
fall in April and May, 1915, is found in an increased 
growth in both Douglas fir and western yellow pine. 
It is also interesting to note that Engelmann spruce 
(Picea engelmanni) growing on a northern aspect in Big 
Cottonwood Canyon, twenty-five miles southeast of Salt 
Lake City, Utah, as its lower altitudinal limit in associa- 
tion with Douglas fir (Pseudotsuga taxifolia), alpine fir 
(Abses lastocarpa), white fir (Abzes concolor) and limber 
pine (Pinus fexilis), showed a decided reduction in the 
length of leaves formed on the tips of the growth of the 
dry season of 1919 in contrast with those formed either 
in 1918 or 1920. The leaves of the 1919 growth aver- 
aged only 0.36 inch long, while those of the 1918 growth 
averaged 0.71 inch long, and those of the 1920 growth 
were 0.71 inch long, based on the measurement of 
thirty typical leaves of each year’s growth. The terminal 
twig growth also showed a similar and very noticeable 
shortening of the 1919 growth, although no measurements 
were secured. 
Kirkwood’s!! data was analyzed and to afford a 
10Korstian, Clarence F. Effect of a late Spring Frost upon 
Forest Vegetation in the Wasatch Mountains of Central Utah. LKc- 
ology 2: 47-52. 1921 
11Loc. Cit. 
