Coastal grasslands' . An ecosystem diagram for the coastal grassland is 

 presented in Figure 3-3. The coastal grassland is a fire disclimax community: 

 a subclimax serai stage maintained through time by the regular disruptive 

 forces of fire. Fire is the essential regulating factor that determines com- 

 munity structure and composition. Without fire, forest or brush species invade 

 and soon dominate former prairie areas (Johnston, 1963; Daubenmire, 1968; Bragg 

 and Hulbert, 1976). Supporting this concept are the following observations: 

 both the live oak woodland and coastal grasslands can exist on the same site 

 (Blakey, 1947); with the cessation of fire, grasslands proceed directly to live 

 oak woodland or other woody community types (Blakey, 1947); and once established 

 the woodlands are not replaced by coastal grasslands (Johnson et al., 1974). 

 The timing and frequency of burning is important in determining the influence 

 of fire. 



Fire regulates the community by favoring species exhibiting various adap- 

 tations and strategies for fire survival. Two general adaptive forms include 

 the survival of underground plant parts and fire-resistant fruits or seeds. 

 Also favored are plant forms that can invade a burned area and quickly establish 

 sufficient biomass to ensure a dependable source of water and light (Clements 

 et al., 1929). Herbaceous species are capable of rapid growth and regeneration 

 from protected underground buds. Woody plants have slower regeneration times 

 and greater sensitivity to fire damage. 



A regime of periodic fires selects against woody seedlings by killing or 

 weakening them. Weakened seedlings are unable to effectively compete against 

 the stresses imposed by dominant herbaceous species. Continued fires help main- 

 tain the competitive edge of grasses. 



Fire elimination enables woody seedlings, once established, to suppress 

 grasses by direct shading. Beyond a critical size and density, hardwood vegeta- 

 tion is normally resistant to prairie fires (Blakey, 1947; Box et al., 1967). 

 Established maritime woodlands and small oak mottes are fire-resistant, due to 

 lack of sufficient ground fuel to support a tree-damaging fire (Johnson et al., 

 1974). 



Again, competition for available soil water is the most important biotic 

 regulating factor maintaining community structure. Light again plays a secon- 

 dary role (Clements et al., 1929). Grasslands will dominate sites with edaphic 

 conditions too severe for establishment of maritime woodlands. Such edaphic 

 conditions may be poorly drained sites with excessive soil moisture or coastline 

 margins with high soil salinities. The species composition of these grassland 

 types will vary depending on the soil moisture, soil salinity, and soil struc- 

 ture. 



The community structure and species composition differ from that of the 

 woodlands, but the ecological roles of the various components are similar. 

 The primary producers include the perennial grasses, perennial herbs, and small 

 components of annuals and suppressed brush (each less than one percent of the 

 total composition). Grazing will alter the primary producer structure to favor 

 woody brush, perennial herbs, and annual weeds. Grazing intensity will regulate 



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