THE BROAD-SCLEROPHYLL VEGETATION OF CALIFORNIA. 87 



individuals survived until the foUowiag November. There is 

 thus a yearly crop of annuals, smaller each season because of com- 

 petition with plants of greater stature. The shrub seedlings suffer 

 also in competition with the sprouts, which finally dominate the 

 area. A few of the seedlings survive, however, especially those of 

 Ceanothus, and form an important part of the stand for a number 

 of years. Ceanothi of several species, when present in large numbers, 

 seem to be indicators of recent disturbance — in other words, chaparral 

 with a large proportion of Ceanothus is likely to be a penultimate 

 stage in a secondary succession. 



When the chaparral is utterly destroyed, whatever the cause, 

 the course of development leading to its reestablishment is usually 

 an exceedingly long one. Often a community of a very different 

 stamp takes possession, which, if the disturbing agency frequently 

 repeats its work, may last indefinitely and simulate a true climax. 

 I have already stated my conviction that the grassland of central 

 California is in part a stage in a secondary succession within the region 

 of the chaparral climax, and that certain trees which habitually 

 grow with the grasses, notably Q. douglasii, have a role in the same 

 process. If such grassland be kept moderately free from grazing 

 and fire, a rough, thick growth of shrubs and half-shrubs often occu- 

 pies it. These are Rhus diversiloha, Sphacele calycina, Diplacus 

 glutinosus, Baccharis pilularis; and they may represent a further 

 stage in the reestablishment of the climax. 



In southern California the coastal sagebrush plays an even more 

 important part in the secondary successions than in the primary. 

 Great areas of it cover the mesas and lower foothills, and its spatial 

 relation to the chaparral is usually exactly analogous to that of the 

 grassland of central California. There is the same patchy alternation 

 between the two, with decrease of the half-shrubs and increase of 

 chaparral as one penetrates a mountain mass. No relation to at- 

 mospheric, soil, or slope factors can be made out, and the inevitable 

 conclusion is that it has replaced the chaparral because of the destruc- 

 tion of the latter by repeated fires which, starting in the valleys, the 

 centers of human habitation, have spread varying distances into the 

 foothills. Here again we find the chaparral following the forest into 

 the mountains, itself followed by the coastal sagebrush, fire favoring 

 the more xerophytic community in each case. The most important 

 species in the secondary coastal sagebrush are Eriogonum fascicu- 

 latum, Ramona nivea, R. stachyoides, and Artemisia californica. 

 Often they are mixed, but sometimes one encounters great stretches 

 of a single species almost pure. The last two are characteristic 

 secondary species as far north as Monterey Bay. In the valley of 

 the Carmel River I found a deserted vineyard that was thickly 

 grown up to these two species — excellent evidence of their rdle in 

 secondary development. 



