NO. 3 DUNKLE : PLANT ECOLOGY, CHANNEL ISLANDS 279 



Larus occidentalism the western gull, nests throughout the whole main 

 western terrace, and the area, as a whole, forms a Suaeda-Lycium-Larus 

 blome. The two nesting sites of Larus on the eastern terrace also sup- 

 ports a vigorous growth of Suaeda. 



The main western terrace ends in an abrupt rocky slope which drops 

 about sixty feet to the smaller western terrace, which extends to the 

 vertical cliffs at the extreme western end of the island. The west facing 

 section of the rocky slope has an Echeveria-0 puntia community with 

 Echeveria albida, Opuntia prolifera, and Tillaea erecta as the most 

 abundant plants. The southern face of this slope drops to low cliffs just 

 back of a narrow beach, and is well covered with Opuntia littoralis, 

 which is very similar to the southern slopes of Anacapa Island. The 

 greater part of this lower western terrace is an A triplex calif ornica 

 community, but near the foot of the rocky slope, where the soil is deeper 

 and the wind not so strong, there is a luxuriant growth of therophytes, 

 geophytes, and chanaephytes. 



Coreopsis association. Coreopsis gigantea is the dominant plant of 

 the island, occurring as individual plants and small colonies in all parts 

 of the island, but the largest and most representative growth occurs on 

 the lower half of the long eastern terrace. This is an area of broad, flat 

 ridges sloping gradually down to the relatively low eastern bluffs. This 

 section of the terrace is traversed by a series of five shallow canyons. 

 A unique schrub community dominated by the grotesque Coreopsis 

 covers all this part of the island, except for the northeast headland, 

 extending, where there is enough soil, almost to the splash zone. Typical 

 associated species are Opuntia littoralis, O. prolifera. Convolvulus oc- 

 cidentalis macrostegius, Lycium californicum, Artemisia californicus in- 

 sularis, and Echinocystis macrocarpa. 



The Coreopsis grows to an average height of four feet on the ridges 

 and up to eight feet in the canyons. Since the branches grow at right 

 angles to the main trunk the Coreopsis shrub forms an intricate tangle 

 which would be almost impossible to penetrate were it not for the 

 extreme brittleness of the plant. A comparatively light touch will break 

 off branches or even the main trunk. This fact might account for its 

 disappearance where extensive grazing has occurred. Only on the eastern 

 island of Anacapa is there a comparable growth of Coreopsis, and there 

 it is being rapidly destroyed by the rabbits infesting that island. In the 

 canyons of Santa Barbara, where the Coreopsis may have an under- 

 growth of O. littoralis and is bound together by long, vigorous lianas 

 of Convolvulus, of the thickness of a fountain pen, or by Echinocystis, 

 the growth does become impenetrable. Coreopsis puts out its feathery 



