forest communities are absent and are replaced by a shrub com- 

 munity. 



The flowering and growth behavior of chaparral shrubs merits 

 some comment. Some shrubs, such as some manzanitas, typically 

 flower in mid-winter (sometimes in December) or very early 

 spring and produce vegetative growth after flowering. At the ter- 

 mination of the vegetative growth, flower buds are produced 

 which remain dormant throughout the succeeding summer and 

 autumn drought, although they burst into flower very quickly in 

 winter. In contrast, some other species (such as Chamise) produce 

 vegetative growth in late winter or early spring and then flower 

 in June. The flower buds of these species are produced at the 

 termination of growth as they are in winter-flowering species, 

 except that there is no bud dormancy; flowering occurs immedi- 

 ately after development of flower buds. One result of this phe- 

 nomenon is that most chaparral shrubs have a similar growing 

 period, but flowering in the community may extend over a period 

 of six months or longer, since various species have different flow- 

 ering periods. The majority of shrubby species in Chaparral flow- 

 er in April, however, when soil moisture conditions are optimal 

 and the air and soil temperatures also are optimal. 



By definition, Chaparral is a plant community in which the 

 dominant shrub species are evergreen. However, most of the 

 chaparral species exhibit a leaf drop of old leaves in early summer, 

 during or at the end of the vegetative growth of new shoots. Be- 

 cause of this timing, the plants retain some leaves the year round. 

 After growth and leaf drop occur, the shrubs become dormant. 

 When the subsequent wet season arrives in late autumn, the chap- 

 arral shrubs are ready to go; they do not have to produce a fresh 

 crop of leaves as do deciduous species. In this respect, at least, 

 chaparral shrubs show an interesting adaptation to the climatic 

 regime under which they exist, an adaptation that enables them 

 to take advantage of the limited period of rainfall. 



Fire and Chaparral 



Chaparral is subject to frequent burning over much of its area 

 of distribution and, indeed, in much of its range it is a subclimax 

 plant community which is maintained because of periodic fires. 



94 



