LAKE-SHORE VEGETATION IN NORTH-CENTRAL COLORADO 73 
good depth of fine-grained soil. While in montane situations willows tend 
to form a complete circum-area of lakes, they are relatively unimportant in 
the shore vegetation of the subalpine region. Where they do occur they 
may initiate a shortened successional series, for they permit the establish- 
ment of Engelmann spruce without the intermediate heath and meadow 
stages. 
"Dry forest" of limber pine and lodgepole pine does not follow meadow 
but belongs to the xerarch series, developing on ridges and on rough, stony 
ground. In time, except where winds are so severe as to blow away the 
humus, Engelmann spruce forest, as the ultimate climatic association, will 
replace the dry forest. 
Summary 
The subalpine zone, 10,000 to 11,500 feet in altitude, in north-central 
Colorado has a large number of small lakes, some of morainal, some of rock- 
basin type. These have a characteristic shore vegetation often developing 
definite circum-areas. The climatic climax association is Engelmann 
spruce forest, and the stages of succession in the filling up of a lake lead 
eventually to this forest. Very few aquatic plants occur, but there is some- 
times a circum-area (usually incomplete) of half submersed sedges. Follow- 
ing this there may be in the more complete cases: (i) a well developed 
moor composed largely of Carex, sometimes separable into moss moor, 
sedge moor, willow moor, rush moor, and meadow moor; (2) a heath asso- 
ciation of Kalmia microphylla and Gaultheria humifusa; (3) meadow asso- 
ciation in which the principal plants are species of Erigeron, Castilleja, 
Ligusticum, Pedicularis, and Vaccinium; (4) forest association, dominated 
by Engelmann spruce. The various associations and their numerous 
subdivisions are described by the author together with their successional 
relations and seasonal aspects. A sketch is given of topography, climate, 
and soil, and a list is made of the characteristic lake-shore plants, with soil- 
moisture index of each. The paper is based upon the study of a large 
number of subalpine lakes in four different counties of north-central » 
Colorado. 
University of Colorado, 
Boulder, Colo. 
LITERATURE CITED 
1. Clements, F. E. Formation and succession herbaria. Univ. Neb. Studies 4: 329- 
355. 1904. 
2. . Plant physiology and ecology, p. 295. New York, 191 7. 
3. Dodds, G. S. Altitudinal distribution of Entomostraca in Colorado. Proc. U. S. 
Nat. Mus. 54: 59-87. 1917. 
4. Nichols, G. E. The interpretation and application of certain terms and concepts in 
the ecological classification of plant communities. Plant World 20: 305-319, 
341-353. 1917- 
5. Ramaley, Francis. Remarks on some northern Colorado plant communities with 
special reference to Boulder Park, Tolland, Colorado. Univ. Colo. Studies 7: 223- 
236. 1910. 
