LAKE-SHORE VEGETATION IN NORTH-CENTRAL COLORADO 63 
Lakes shut in by steep slopes often show no special shore vegetation. 
The Engelmann spruce forest extends down close to the lake edge, and here 
there may be a zone of rocks with almost no vegetation at all. This con- 
dition obtains particularly where the lake level fluctuates from year to 
year or in different months of the same season. Most lakes have some parts 
of the shore either barren or else covered with forest. Lakes which show 
no true shore vegetation furnish nothing for discussion in the present paper. 
Fig. 5. One of the small Forest Lakes (altitude 10,800 feet); a shallow pond with 
much infilling and showing complete circum-areas of moss moor and sedge moor. A half 
submersed belt of Carex aquatilis runs about one third of the way around the lake. Nearly 
every one of the various lake-shore associations is represented in some part of the area 
surrounding this lake. Photograph by Dr. W. W. Robbins. 
Many lakes have gently sloping banks for a part of their circumference. 
On these more moderate slopes a true shore vegetation develops, determined 
by differences from the forest in soil quality, soil moisture, and soil tempera- 
ture. A common arrangement of the vegetation of these lakes is in three 
clearly-marked circum-areas (8). As a rule, some of the associations are 
absent at certain points. Willows may be present only near the lake inlet 
and outlet (see table 4). 
Table 4. Suhalpine shore vegetation; condensed classification 
1. Moor; next to water: 
a. Sedge moor; chiefly Carex, with Caltha, Bistorta, Clementsia, and other marsh 
plants. 
h. Willow moor (willow scrub) ; farther from the water but the soil very wet. The 
herbaceous vegetation is chiefly Carex with some shade-enduring grasses and 
dicotyledons. 
2. Meadow; on drier ground, but the soil fairly deep and of moderately fine texture. 
Often this is a close association of many species of flowering herbs. 
3. Forest; Engelmann spruces chiefly, if the soil is deep, but lodgepole pine and limber 
pine on steeper slopes and on ridges with scanty soil. 
