72 
FRANCIS RAM ALE Y 
During the autumnal period the summer-blooming plants are in fruit 
and a few of them continue to bloom for a time, especially Erigeron saU 
suginosus, Campanula petiolata, the Castillejas, and the Arnicas. True 
autumn-blooming plants are the gentians Amarella, Chondrophylla, and 
Dasystephana, also Antennaria umhrinella and Ligusticum tenuifolium. 
The snows which usually come about the first week in September melt 
away in a few days, and some of the plants continue in bloom up to about 
September 20, or occasionally even to October i. 
Successions 
The character of succession on the lake shores here described is so 
obvious that an extended discussion will not be necessary. It needs to 
be kept in mind that the topography of the area is "new." There is com- 
paratively little soil anywhere except in depressions where it has been 
washed down from adjacent slopes. Lake bottoms are typically of boulders. 
Climate is of the cold, moderately wet type which favors the development 
of coniferous forest. Engelmann spruce forest is the ultimate climatic 
association and appears wherever edaphic conditions are at all favorable. 
A few subalpine lakes, especially those at lower altitudes close to 10,000 
feet, have a moderate amount of aquatic vegetation, chiefly Potamogeton 
spp. and Sparganium angustifoUum. These plants contribute slightly to 
the filling up of lakes. At higher altitudes they are generally absent and 
the only lake vegetation of consequence is Carex, which may form in places 
a strip of half submersed plants extending into the water from the moor. 
The Carex here is commonly C. aquatilis, which is also the chief sedge of 
the moor that surrounds subalpine lakes. 
Often the vegetation advances very slowly into the lake because of the 
heaving action of ice. This thrusts itself into the bank and destroys 
vegetation. It may give rise to an elevated "rim" as shown by Robbins 
(11), projecting out a few decimeters over the edge of the water. 
Infilling of subalpine lakes is, it will be recognized, largely a physio- 
graphic process depending upon stream sediment chiefly near the inlet, or 
upon storm wash from surrounding slopes. When, however, a lake has 
once been filled so that the water is quite shallow, then a rapid invasion by 
Carex may occur. 
The normal positions of the various plant communities show their 
successional relations. Half submersed Carex association is followed by 
moor, and this by heath and meadow and forest. When level ground is 
raised by accumulation of plant remains or by alluvial wash then a later 
successional stage of vegetation develops. The same change occurs when 
the lake level is lowered. One or more stages may be skipped. 
Moss moor is usually the wettest part of the moor. As vegetation 
advances this becomes drier and changes to ordinary sedge moor or to 
meadow moor. The willow moor stage may follow sedge moor if there is a 
