18 (60) 



ZONES OF 



VEGETATION 



LAYERING 



Figure 3. The distribution of some common seaweeds within giant kelp forests. Plants 

 in the four zones of vegetation layering include (1) small filamentous species and 

 encrusting coralline algae; (2) bottom canopy plants such as Gel idium , Cal 1 iarthron , 

 and Plocamium ; (3) understory canopy kelps such as Pterygophora , Eisenia , and 

 Laminaria ; and (4) midwater and surface canopy plants such as Egregia , Macrocystis , and 

 Nereocystis . This is a generalized diagram and some species do not co-occur in the 

 same site (modified from Dawson and Foster 1982). 



essentially the result of a "numbers 

 game": How many plants are in an area? 

 How fast do they grow? How long do they 

 live? What is their reproductive output? 

 How many new recruits appear? Plants also 

 respond differently when placed in differ- 

 ent conditions, such as those which occur 

 naturally at different localities, and at 

 different depths within the same locali- 

 ties. These sorts of demographic 

 questions remain to be answered primarily 

 by field-based studies. 



This approach has generally not been 

 followed in giant kelp forest research, 

 and there is a definite bias in the 



literature in studies done j_n situ with 

 Macrocystis . Most field research has been 

 done at a very few sites (near Point Loma, 

 San Diego County; the Palos Verdes area, 

 Los Angeles County; and near Santa 

 Barbara) to resolve questions about 

 habitat loss and restoration. This is due 

 to historic reasons, including the large 

 population centers in southern California, 

 kelp harvesting in the area, the presence 

 of several universities with facilities 

 for marine research, a sudden awareness of 

 environmental problems coincident with the 

 increase in sewer discharges, and the 

 disappearance of large kelp forests on the 

 Palos Verdes Peninsula and near Point 



