CLIMATIC AND EDAPHIC INDICATORS. 355 



when it is from 10 to 12 years old, the next stand will consist principally, if 

 not wholty, of knobcone pine. The knobcone pine begins producing seed 

 when it is 6 years old and is producing good crops of seed at 10 years, while the 

 white pine and Douglas fir bear only occasional cones at ages under 12 years. 

 Therefore the knobcone pine is the only species which has any seed present to 

 produce a forest stand following the second fire. Instances of such types are 

 the knobcone pine types on the Siskiyou National Forest. " 



Scrub communities are regularly indicators of fire where they are in contact 

 with forest. In fact, sagebrush appears to be a fire subclimax in the pifion- 

 cedar woodland, as well as in the southern portion of the Coastal chaparral. 

 Chaparral, however, is the typical scrub indicator of fire in woodland and 

 forest. This is as true of the subclimax chaparral along the eastern edge of the 

 grassland climax as it is of the Petran and Coastal associations. The most 

 characteristic development of chaparral as a burn indicator is found in the 

 montane forest in California, where the scrub persists as a more or less com- 

 plete forest layer (p. 213; cf. Mitchell, 1919: 39; Foster, 1912: 212). Chaparral 

 owes its importance as a fire indicator to its remarkable ability to form root- 

 sprouts, and hence the form of the dominant shrubs is itself a response to fire. 

 Fire in chaparral leads to a short subsere, in which the herbaceous stages per- 

 sist for only a few years before the new shoots overtop them. Repeated fires 

 may produce a subclimax characterized by Eriodictyum, or by Artemisia, 

 Salvia, and Eriogonum. In the region of its contact with woodland and forest, 

 chaparral is an indicator of forest burns, and consequently is subclimax. 

 This is true in both associations, but is more marked in the Sierran, perhaps 

 because of its greater massiveness. Munns (1919:9) has assumed that all 

 of the latter is a temporary type due to fire, but this certainly seems not to be 

 true of the regions with 12 inches or less of rainfall. This assumption is 

 largely due to a misconception of what constitutes the test of a climax. Both 

 of the tests used, the successful planting of trees and the existence of scattered 

 trees and tree stands, would prove the grassland climax to be a temporary 

 one. The critical processes in the establishment of a forest are seed-pro- 

 duction, dissemination, and ecesis, and artificial planting is powerless to throw 

 light upon the outcome of these. Further studies of the chaparral formation 

 during the past three years have confirmed the view expressed in 1916 (Plant 

 Succession, 180) that it constitutes a real climax, though portions of it are 

 undoubtedly subclimax. This view is supported by the conclusions of Cooper 

 (1919), who has made an intensive study of the California chaparral upon the 

 instrumental and successional basis (plate 88). 



Grazing indicators. — With reference to the forest itself, only those grazing 

 indicators are of importance that indicate overgrazing, and hence actual or 

 potential damage to the reproduction. The presence of the usual overgraz- 

 ing indicators would serve this purpose, but these are usually accompanied by 

 evidences of damage to the seedlings as well. However, while abundant 

 evidence of this nature denotes overgrazing, it is still a question as to just 

 when this becomes critical in the reproduction of the forest. In fact, it is 

 clear that the critical degree of overgrazing depends much upon the nature 

 of the community, time of year, age of the seedlings, and other factors. Much 

 light has been thrown upon the problem by three careful studies in the national 

 forests. 



