86 THE BROAD-SCLEROPHYLL VEGETATION OF CALIFORNIA. 



brief sketch must here suffice. The pioneers upon beach and dune are 

 mainly strand-succulents, such as Abronia latifolia, A. maritima, 

 A. urnbellata, Mesembryanthemum cequilaterale, Convolvulus soldanella, 

 and Franseria bipinnatifida. These are followed by a group of 

 half-shrubs, including Eriogonum parvifolium, Lupinus chamissonis, 

 Ericameria ericoides, and Eriophyllum stcechadifolium. In the 

 Monterey region, on an area of very ancient dunes, the succession 

 may be traced farther. Adenostoma and Arctostaphylos pumila follow 

 the half-shrubs and are themselves succeeded by Arctostaphylos vestita 

 and other relatively less xerophytic chaparral species. This commu- 

 nity is displaced by a low forest of Quercus arjrifolia, to which, on 

 the Monterey Peninsula, is added Pinus radiaia. This is the local 

 climax, more mesophytic in type than in the regions adjacent, 

 probably because of more favorable moisture conditions. 



Secondary Successions. 



Two classes of secondary successions may be distinguished — those 

 after occasional burning or clearing (where the basal portions of the 

 shrubs are left to sprout) and those after thorough destruction of 

 the original vegetation, either by the grubbing out of the underground 

 parts or by burning at very frequent intervals. 



In the first case the succession is a short one, bringing a return 

 practically to the original state in a very few years. The composition 

 of the new chaparral is for a time somewhat different from what it 

 was formerly because of the persistence of some of the plants which 

 came in after the fire. The following outline gives the general features 

 of the development as determined by a quadrat study near Palo 

 Alto and observation elsewhere. Most of the species sprout readily 

 from the stump, and the new shoots grow with astonishing rapidity, 

 even in the driest part of the dry season. Six weeks after the Ojai 

 Valley fire of June 1917, sprouts were found which had attained a 

 height of nearly a meter. The sprouts therefore have a tremendous 

 advantage over any seedlings that may start, especially if the fire 

 occurs early in the dry season, since germination can not take place 

 until the rains begin. With the first rains, seeds which have blown in 

 or lain dormant germinate in enormous number and great variety. 

 Among these are many of the shrub species, which gradually decline 

 in number as the years pass. In a permanent quadrat 5 meters 

 square, near Palo Alto, 562 shrub seedlings appeared during the 

 first rainy season. Seven years later the number of survivors (in- 

 cluding some new germinations) was 189. Of the first arrivals, 13 

 per cent were Adenostoma and 62 per cent Ceanothus cuneatus, 

 although the original growth was nearly pure Adenostoma. The 

 greatest number of herbs appeared during the second rainy season. 

 The 2,841 recognizable individuals comprised 28 species, of which all 

 but half a dozen were annuals. Of this large number, only 13 



