228 CLIMAX FORMATIONS OF WESTERN NORTH AMERICA. 



Factor and serai relations. — Climatic data for the pine-larch association are 

 almost completely lacking. In the Sierras, the precipitation ranges above 

 50 to 75 inches, and the snowfall may be as great as 300 to 900 inches, or 50 

 to nearly 100 per cent of the total. The general climatic relations are as 

 already indicated for the formation. 



The water relations of the dominants are imperfectly known. Picea, 

 Tsuga, and Abies lasiocarpa grow generally in the moister areas, Pinus monti- 

 cola, P. contorta, Larix, and Abies magnified in intermediate ones, and Pinus 

 albicaulis, flexilis, and balfouriana in the drier. The general light relations 

 may be indicated by the following table of tolerance in which the order is 

 from the intolerant to the tolerant. The order of the dominants likewise 

 indicates the serai sequence in so far as it is known. 



1. Pinus balfouriana. 



2. Pinus flexilis. 



3. Pinus albicaulis. 



4. Larix lyallii. 



5. Pinus contorta. 



6. Abies magnifica. 



7. Pinus monticola. 



8. Abies lasiocarpa. 



9. Picea engelmanni. 

 10. Tsuga mertensiana. 



SOCIETIES. 



The Sierran subalpine forest does not have a large number of societies 

 peculiar to it. The majority of those which occur in it have been derived 

 from the montane forest or the alpine meadow. This is especially true of the 

 shrubs, many of which extend up from the subclimax chaparral (p. 213). 

 The following list applies particularly to California: 



Shrubs: 



Arctostaphylus nevadensis. 

 Ribes viscosissimum. 

 Ribes montigenum. 

 Potentilla fruticosa. 

 Haplopappus suffruticosus. 

 Lonicera conjugialis. 

 Juniperus communis. 

 Vaccinium occidentale. 

 Vaccinium caespitosum. 

 Ceanothus cordulatus. 

 Acer glabrum. 



Herbs: 



Artemisia norvegica. 

 Hieracium gracile detonsum. 

 Sibbaldia procumbens. 

 Haplopappus macronema. 

 Potentilla breweri. 

 Ranunculus alismifolius. 

 Phacelia hydrophylloides. 

 Whitneya dealbata. 

 Orthocarpus pilosus. 

 Erysimum asperum. 

 Eriogonum marifolium. 

 Eriogonum ursinum. 

 Polygonum davisiae. 



THE ALPINE MEADOW CLIMAX. 



CAREX-POA FORMATION. 



Nature. — The alpine climax is essentially a grassland in appearance, though 

 it is chiefly composed of sedges. The dominants are all grasslike in character 

 and the most typical regularly form a turf which rivals that of the buffalo- 

 grass in compactness. They are 2 to 6 inches high for the most part, though 

 some exceed this in subclimax situations or in the lower part of the zone. The 

 total number of dominants is greater than for any other formation, but the 

 number in a particular community is rarely excessive. A characteristic 

 feature of the dominants is their remarkable range, nearly half of them occur- 

 ring from Greenland to Colorado, California, and Alaska, wherever alpine or 

 arctic habitats are found. A large number of these grow in similar situations 



