Reproduction of Chaparral Shrubs After Fire: A Comparison of Sprouting and Seeding Strategies

The relative ability of sprouting and nonsprouting chaparral shrubs to recover from fire was studied by examining popula- tion of congeneric pairs of species in burned and adjacent unburned areas. The pairs of species selected, with the nonsprouting species named first, were Arctostaphylos glauca ? A. glandulosa and Ceanothus greg- gll - C. leucodermls. Data were also obtained on certain associated species, particularly Adenostoma fasclculatum. The numbers, sizes and condition of the component species at each of the sites were measured. Both sprouting and nonsprouting species showed vigorous recovery from fire. It seemed likely that the burned stands would eventually reach a state of development comparable to that shown in the preburn stand without any significant shifts in composition Mortality of shrubs resulting from the fire was complete for nonsprouters but varied in sprouting species. In some there was essentially no mortality, while in others, especially Adenostoma, it was rather high. Seedling establish- ment in the shrub species varied markedly and seemed to be correlated with the degree of fire-caused mortality. A profound difference was observed in the life histories of the two nonsprouting shrubs. Whereas Ceanothus greggll produced a very high number of seedlings after fire, Arctostaphylos glauca produced substan- tially fewer. A comparison of the density-size distribution of live and dead stems indicated that C. greggll suffers high mortality early in suc- cession, but A. glauca loses very few individuals even after 90 years without fire. In light of these results a model is proposed which we be- lieve explains the adaptive significance of the obligate-seeding strategy in the southern California chaparral.

[1]  J. Keeley,et al.  Energy Allocation Patterns of a Sprouting and a Nonsprouting Species of Arctostaphylos in the California Chaparral , 1977 .

[2]  V. Grant.  Genetics of Flowering Plants , 1976 .

[3]  J. Keeley.  Longevity of nonsprouting Ceanothus , 1975 .

[4]  H. Biswell.  10 – Effects of Fire on Chaparral , 1974 .

[5]  E. Charnov,et al.  Life-History Consequences of Natural Selection: Cole's Result Revisited , 1973, The American Naturalist.

[6]  P. Raven.  The Evolution of Mediterranean Floras , 1973 .

[7]  D. I. Axelrod.  History of the Mediterranean Ecosystem in California , 1973 .

[8]  R. J. Vogl,et al.  Fire and Manzanita Chaparral in the San Jacinto Mountains, California , 1972 .

[9]  M Dodge,et al.  Forest fuel accumulation--a growing problem. , 1972, Science.

[10]  G. Stebbins.  Adaptive Radiation of Reproductive Characteristics in Angiosperms, II: Seeds and Seedlings , 1971 .

[11]  Ted L. Hanes.  Succession after Fire in the Chaparral of Southern California , 1971 .

[12]  R. Specht.  A comparison of the sclerophyllous vegetation characteristic of mediterranean type climates in france california and southern australia i structure morphology and succession , 1969 .

[13]  N. West.  Rodent‐Influenced Establishment of Ponderosa Pine and Bitterbrush Seedlings in Central Oregon , 1968 .

[14]  Ted L. Hanes,et al.  Postfire Chaparral Succession in Southern California , 1967 .

[15]  George W. Cox,et al.  Laboratory Manual of General Ecology , 1967 .

[16]  G. Williams.  Adaptation and Natural Selection , 2018 .

[17]  Michael T. Ghiselin,et al.  The Economy of Nature and the Evolution of Sex , 1964 .

[18]  Philip V. Wells,et al.  Vegetation in Relation to Geological Substratum and Fire in the San Luis Obispo Quadrangle, California , 1962 .

[19]  J. S. Horton,et al.  Development of Vegetation after Fire in the Chamise Chaparral of Southern California , 1955 .

[20]  H. Lewis,et al.  The Centers of Distribution of the Chaparral and Coastal Sage Associations , 1942 .