226 CLIMAX FORMATIONS OF NORTH AMERICA. 



Cooper (1908 : 319) has studied the development of alpine vegetation on 

 Long's Peak in Colorado. 



On exposed slopes the dry meadow succession begins vnth lichens, passes 

 through a stage of xerophytic herbs, and culminates in the dry meadow char- 

 acterized by Silene acaulis, Sieversia turbinata, Dryas octopetala, Phhx caespi- 

 tosa, Campanula rotundifolia, and Rydbergia grandiflora. The wet meadow- 

 forest succession may begin with mosses in the wetter places, or with plants of 

 the dry meadows in the rock fields or crevices. The former passes into a 

 sedge-grass stage and the two successions converge into the mature wet meadow 

 characterized by Lycopodium, Carex, Sedum, Kalmia, Gentiana, Swertia, and 

 Elephantella. These are followed by shrubs, commonly Betula glandvlosa, 

 Dasyphorafruticosa, and Salix chlorophylla. These in their turn are succeeded 

 by a forest of Picea engelmannii and Abies lasiocarpa, usually much dwarfed 

 as it approaches the timber-line. 



Schneider (1911 : 289) has considered in some detail the deviations of the 

 rock prisere from the normal sequence in the Pike's Peak region, and has also 

 studied the reactions to some extent: 



The grassland and thicket stages are often much reduced, and may even be 

 entirely omitted. In such cases, the pines invade the gravel-slides directly. 

 On the more favorable north slopes the grass stage often forms a dense sod, 

 which often seems to close the succession, probably in consequence of grazing. 



Watson (1912 : 213) states that the biotic succession in the Sandia Mountains 

 of New Mexico is the following: 



Bare rock first covered with crustose lichens, then foliose lichens, mosses, 

 herbs, oaks, followed in some cases directly by Douglas spruce, and in others 

 by aspen, then spruce, and then as physiographic succession comes in, poplars, 

 pines, and box-elders in the canon, and pine, pinon, and cedar on the slopes, 

 until the ultimate formation of the mesa is reached. 



Weaver (1914 : 273) has traced the succession from prairie to the climax forest 

 in northeastern Washington and adjacent Idaho, and has studied the reaction 

 upon evaporation: 



The bunch-grass rimrock association of the exposed canon banks yields to 

 the characteristic prairie. In more mesophytic areas the latter is replaced by 

 a scrub of Symphoricarpus, Rosa, Prunus, Crataegus, Amelanchier, Opulaster, 

 and Populus tremuloides, which are the forerunners of the Pinus ponderosa 

 woodland. This is usually succeeded by Pseudotsuga, which passes into a 

 subclimax of Pseudotsuga and Larix, often with Abies grandis. The real 

 climax consists of the cedar (Thuja plicata) consociation. 



SUBSERES. 



Bell (1897) has given such a graphic picture of the fires in the great forests 

 of the Northwest and of the resulting subsere that his account is repeated in 

 some detail: 



"An old forest of this region, because of its practically unlimited extent and 

 dense growth, forms a mass of fuel favorable to support a continuous sheet of 

 flame on a grand scale, and yet is sufficiently open to furnish a plentiful supply 

 of air to carry on the conflagration. After the prolonged hot weather and 

 drouth of the summer months, the moisture has become thoroughly dried out 

 of the gWDomy boughs of the standing trees, leaving their great store of resin 

 and turpentine as well as the wood itself ready for burning. The ground cover 

 of mosses and fallen timber is also dry. The fire that may then be started 



