202 CLIMAX FORMATIONS OF WESTERN NORTH AMERICA 



Decrease of temperature with altitude. 



Shreve (I. c, 46) has made a thorough study of the climatic relations of the 

 Santa Catalina Mountains, and the three preceding tables for the woodland 

 have been taken from his tables for rainfall (52), evaporation (64), and temper- 

 ature (75). 



SOCIETIES. 



The oak-cedar woodland has few distinctive societies. It is in constant or 

 repeated contact with desert scrub, grassland, chaparral, and montane forest, 

 and holds practically all its subdominants in common with one or more of 

 these. Because of its savannah-like contact with the desert plains, the 

 majority of the societies have been derived from the latter. It is desirable 

 to consider here only those which occur in the partial or complete shade of the 

 woodland as a dominant community. The societies vary with the season and 

 altitude, but a detailed treatment of them is impossible at present. 



Solidago speciosa. 

 Artemisia gnaphalodes. 

 Monarda citriodora. 

 Hymenothrix wrightii. 

 Gaura suffulta. 

 Desmodium batocaule. 

 Sporobolus confusus. 

 Crotolaria lupulina. 



Shade Societies. 

 Gymnolomia multiflora. 

 Haplopappus gracilis. 

 Polygala alba. 

 Comandra umbellata. 

 Hymenopappus mexicanus. 

 Cordylanthus wrightii. 

 Andropogon scoparius. 



Bouteloua racemosa. 

 Muhlenbergia affinis. 

 Rhus radicans. 

 Rhus trilobata mollis. 

 Pteris aquilina. 

 Pellaea wrightiana. 

 Cheilanthes fendleri. 



THE PINE-OAK WOODLAND. 



PINUS-QUERCUS ASSOCIATION. 



Nature and extent. — The first suggestion that the community of Pinus 

 sabiniana and Quercus douglasii, so typical of dry foothill slopes in central 

 California, constituted a third association of the woodland formation was due 

 to its general likeness in appearance and position to the oak-cedar woodland. 

 The probability of this relationship has been greatly increased by the discov- 

 ery that these two characteristic dominants are associated with pifion and 

 cedar where their ranges overlap. This is pointed out by Abrams (1910: 317) : 



" The Upper Sonoran area on the desert slopes of the mountains is commonly 

 called the pifion and juniper belts, the two conifers, Pinus monophylla and 

 Juniperus calif ornica, being the most characteristic species. Several trees and 

 shrubs which belong properly to the Intramontane district penetrate through 

 Tejon Pass and extend in a narrow belt along the western slope of Antelope 

 Valley. The normal flora of the desert slopes is modified in this section by the 

 presence of such species as Pinus sabiniana and Quercus douglasii." 



A further search for groupings of Pinus sabiniana or the associ^ed oaks 

 with pifion or cedar has disclosed the fact that Coville (1893) had noted these 

 repeatedly in the southern Sierra Nevada: 



