LAKE-SHORE VEGETATION IN NORTH-CENTRAL COLORADO 6 1 
Soils throughout the area studied are derived primarily from granitic 
rocks. On many ridges the material is a compact disintegrated granite^ 
and the shores of subalpine lakes are often of this material interspersed 
with large and small boulders. At inlets and outlets, and wherever an 
accumulation of wash from adjacent slopes occurs, the soil is a black loam. 
Fig. 3. Part of Corona Lake (altitude 11,165 feet), a high subalpine lake without 
any complete circum-areas of vegetation. Numerous large rocks are to be noted along 
the shore which show that there has been very little infilling. In the lower right-hand 
corner of the picture an Engelmann spruce is seen; behind this is a clump of willows; 
farther around is sedge moor; then more willows. 
Here sedge moor and willow moor (willow scrub) develop. Typical sub- 
alpine meadow is found on lighter, better-drained soil, a sandy loam which 
occurs often as a circum-area of lakes between the moor and the forest. 
Soil moistures have not been so fully determined as soil temperatures. 
Figures for July, 191 8, at Redrock Lake (altitude 10,100 feet) are, however, 
available (9). They indicate an abundance of moisture. Averages are 
shown in table 3. 
Table 3. Soil moisture percent at j dm. depth during July, igo8, at 
Redrock Lake in the subalpine zone 
Subalpine sedge moor, near water 65 
Subalpine meadow, on higher ground 21 
Subalpine spruce forest (dense) 29 
Subalpine forest openings (dry places) 7 
No studies of wilting coefficients have been made, but so far as the 
writer's observations go there is little wilting of vegetation even in the 
driest weather. 
Probably the chief limiting factors for plant growth around subalpine 
lakes are low temperature, extreme shortness of season, and shallow soiL 
