THE CORDILLERAN CLIMAXES. 225 



THE CORDILLERAN CLIMAXES. 

 PRISERES. 



Clements (1904^ : 329) distinguished the formations of the Rocky Mountains 

 in Colorado and analyzed them into consocies (facies) and societies (principal 

 species). The development of the coniferous forest was interpreted as con- 

 sisting of the following stages: (1) the Aletes-Mentzelia gravel-slide; (2) the 

 Elyrmis-Muhlenbergia half gravel-slide; (3) the Pinus ponderosa-flexilis forma- 

 tion; (4) the Picea-Pseudotsuga formation; and (5) the Picea-Pinus aristata 

 formation. As a consequence of fire, the Populus tremulmdes forest might 

 replace for a time any of the last three communities. 



The discussion of succession in "Development and Structure of Vegetation" 

 (1904 : 91) and "Research Methods in Ecology" (1905 : 251, 170) was drawn 

 chiefly from studies made in the Colorado mountains, but it dealt primarily 

 with processes and principles. The following outline indicates the sequence 

 of the most important priseres and subseres: 



"TMaspi-Picea-sphyrium; pennycress-spruce talus succession. 



Tfdaspi-EriogonumHshalicium; pennycress-eriogonum gravel-slide formation. 



Elymus-Gilia-chalicodium; wildrye-gilia half gravel-slide formation. 



Quercus-Holodiscus lochmodium; oak-fringewood dry thicket formation. 



Pinus-xerohylium; pine dry forest formation. 



Picea-Pseudotsuga-hyliwm; spruce-balsam forest formation. 

 Bryum-Picea-pyrium; moss-spruce bum succession. 



BTyum-telmatium; moss meadow formation. 



Asier-Chama^nerium-poium; aster-fireweed meadow formation. 



DescharrvpsiorCarex-poium; hairgrass-sedge meadow. formation. 



SaUx-Betvlor-helolochmium; willow-birch meadow thicket formation. 



Populus-hylium; aspen forest formation. 



Picea-hylium; spruce forest formation. 

 Lecanora-Carex-hedium; lichen-carex residuary succession. 



Lecanorai-Gyrophora-petrium; crustose lichen rock formation. 



ParmdiarCetrariaHiMicmm; foliose lichen gravel-slide formation. 



ParonychiaSilene-chalicodium; naUwort-campion gravel-slide formation. 



Carex-Campanulorcorypkium; sedge-bluebell alpine meadow formation. 

 Eragrostis-Helianthiis-xerasium; eragrostis-sunflower drainage succession. 



Eragrostis-Polygonum-telmatium; eragrostis-heartsease wet meadow formation. 



Helianthus-Ambrosiorchledium; sunflower-ragweed waste formation." 



Whitford (1905 : 194) has indicated the general course of succession in the 

 forests of the Flathead Valley, Montana: 



The aquatic stages consist of Myriophyllum, Nymphaea, Brasenia, Pota- 

 mogeton, and Hippuris. The sedge associes contains Carex ubrieulata, C. 

 viridula, C. hystridna, Calamagrostis, Phalaris, Sdrpus lacustris, Bromus 

 Muhlenbergia, etc.. In Sphagnum meadows, Menyanthes, Drosera, Comurum, 

 Eriophorum, and Betula pumila are characteristic. Salix and Alnus often 

 form the next stage, or they are absent, and a forest of Picea mgelmannii, 

 Populus angustifolia, P. tremviaides, and Betula papyrifera develops directly! 

 This is replaced gradually by a forest of Larix ocddentalis and Psevkotmga 

 mucronata, in which AUes grandis and Pinus monticola are often important. 

 This forest is regarded as the climax, and it is also found developing on prairies 

 of the region as they grow more mesophytic. 



