THE SAGEBRUSH CLIMAX. 155 



Valley and east of the Cascades, and California east of the Sierra Nevada. 

 Disregarding the interruption due to isolated mountain ranges, this consti- 

 tutes the largest central mass exhibited by any formation west of the prairies 

 and plains. Tongues of sagebrush stretch out from this mass into eastern 

 Montana, central Colorado, northern New Mexico, and Arizona, southern 

 California and Mexico, while climax outposts are found in southeastern 

 and eastern Washington, and even in southernmost British Columbia. These 

 are practically all extra-regional, persisting because of peculiar local con- 

 ditions or because the proper climax has not yet occupied all of its climatic 

 region. 



Subclimax sagebrush. — Much if not all of this marginal portion of the for- 

 mation is subclimax in nature . This seemsto be true also of long stretches which 

 are apparently an intrinsic part of the central mass. This relation is obvious 

 where sagebrush comes in contact with the true woodland climax or with the 

 montane forest, because of the dominating relation of the trees. It is less clear 

 in the case of transitions between sagebrush and chaparral or desert scrub, 

 where the dominants are more nearly of the same size and nature. In such 

 instances, the mixed community not only seems but actually is a fairly per- 

 manent community, of which the real climax relationship can only be deter- 

 mined by prolonged study. 



The longest contact of the sagebrush is with grassland. It meets the bunch- 

 grass prairies in Washington, Oregon, Idaho, Montana, and Utah, the mixed 

 prairies in Montana, Wyoming, and Colorado, and the short-grass plains in 

 western Colorado, northern New Mexico and Arizona, and southeastern 

 Utah. The ability of the sagebrush and grassland to live together is shown 

 not only by the very broad transition between them all along the line of con- 

 tact, but also by the fact that such dominants as Agropyrum glaucum and 

 Stipa comata are found more or less abundantly throughout the climax area 

 of the formation. 



The actual relation between sagebrush and grasses is readily disclosed 

 wherever sagebrush has been cleared and often also where it has been burned. 

 When the short subsere which results ends again in sagebrush after a few years, 

 the area may well be regarded as a part of the sagebrush climax. This can 

 usually be anticipated by the vigor with which the shrubs form root-sprouts, 

 as well as by the failure of the grass dominants to appear in abundance during 

 the first two or three years. If the grasses do develop abundantly during the 

 first few years and especially the first year, so that they dominate the root- 

 sprouts of the shrubs, the area is to be regarded as belonging to the grassland. 

 Examples of this sort have repeatedly been found since 1913 in what appeared 

 to be typical sagebrush areas. Festuca ovina, Agropyrum glaucum, and A. 

 spicatum have frequently been found to replace cleared or burned sagebrush in 

 Oregon. Agropyrum glaucum and Stipa comata have been seen in the same 

 role in many parts of Idaho, northern Utah, and southwestern Wyoming. In 

 addition, the grass dominants have been found killing out the sagebrush as a 

 direct result of competition for water. This is not surprising along the 

 eastern edge in Wyoming where the grasses have a definite climatic advantage, 

 but it is unexpected in Utah and Nevada, where the advantage is reversed. 

 Sagebrush has been seen nearly dead or dying as the result of water com- 

 petition with Agropyrum glaucum, A. spicatum, Bouteloua gracilis, and Stipa 



