laceae, Plate 4D), and Golden Corydalis (Corydalis aurea, Fumari- 

 aceae) are common on burned areas, although they may also 

 appear in areas that have been ecologically disturbed by other 

 agencies. The fire annuals listed above persist for many years as 

 seed in Chaparral; indeed, the viability of their seed may last as 

 long as a hundred years or more. In areas that have not been 

 burned for sixty years, study of the soil has revealed the presence 

 of viable seeds of these plant species, most of these seeds pro- 

 duced by the previous generation of plants that grew on the site 

 when it last burned. Seeds of fire annuals are obviously tolerant 

 of the very high soil temperatures that result from chaparral fires. 

 Also, many of these species require a high-temperature shock in 

 order to germinate, and thus have a built-in mechanism which 

 informs the seeds that a fire has occurred. In the autumn after 

 the fire, germination of seeds occurs after the first heavy rains 

 fall; in the subsequent spring, the former chaparral site is covered 

 with thousands of individuals of these fire annuals, the offspring 

 of parents that occupied the site up to a century before. These 

 fire annuals are accompanied by various other annual plant 

 species that are not necessarily typical of burned areas. Some 

 herbaceous perennials also appear in profusion on burned lands. 

 However, all these plants are also accompanied by seedlings of 

 chaparral species and by the rapidly growing shoots of the crown- 

 sprouting shrubs. As a result, within a few years the chaparral 

 shrubs have re-occupied the site and the annuals disappear - until 

 another fire occurs. 



Most chaparral areas that have been studied show a recent his- 

 tory of fire. In areas where Chaparral is not a climax plant com- 

 munity, it is likely to be replaced successionally by one of the 

 various woodland communities present in the vicinity. Seedlings 

 of trees that become established among chaparral shrubs even- 

 tually increase in size and abundance, and the chaparral shrubs 

 correspondingly begin to decline. However, there are areas where 

 Chaparral is maintained because the local soil conditions are un- 

 suitable for the establishment of tree species. In these circum- 

 stances. Chaparral is a climax plant community. 



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