no. 3 dunkle : plant ecology, channel islands 261 



The Influence of Man 



The environmental factors of wind, sun, and temperature operate 

 slowly in producing climatic changes and cannot be readily controlled, 

 whereas the activities of man can be. Man has introduced many grazing 

 and browsing animals as well as aggressive plant competitors with the 

 native plants. These agencies have been immensely destructive to the 

 original island vegetation. Few records have been kept of the more direct 

 activities of man. Disastrous fires have occurred on most, if not all, of 

 the islands. Thus Santa Barbara Island was burned over in 1918 to 

 clear the small arable areas for agricultural purposes (Meadows, 1944). 

 Trees have been cut on Santa Rosa, Santa Cruz, San Clemente, and 

 Santa Catalina for fuel, and timber is said to have been used for ship 

 repairs in the early days. Small areas have been under cultivation on 

 Santa Cruz, Santa Barbara, and Santa Catalina. However, the plants 

 and animals introduced by man have been a major factor in changing 

 the aspects of the native vegetation. 



Destructive Grazing and Erosion 



Erosion has assumed dangerous proportions on several of the islands 

 owing to a century or more of destructive overgrazing. The island of 

 San Miguel was used as a sheep ranch prior to 1850 (Ellison, 1937) 

 and has been continuously grazed since, though this has been much 

 restricted in recent years. Santa Rosa was stocked with sheep in 1844 

 and sixty thousand head of sheep were there in 1874 (Ellison, 1937). 

 There were two hundred sheep on Santa Cruz in 1852; in 1855 the 

 sale of wool from the island brought $22,000.00; in 1877 twenty 

 five thousand sheep were killed for tallow, glue, and hides. Sheep were 

 being raised on San Clemente as early as 1877 (Meadows, 1944) and on 

 Santa Catalina in considerable numbers for some years prior to the pur- 

 chase of the island by the Banning brothers in 1892. Sheep were grazed 

 on at least the middle island of Anacapa for several years. Goats have 

 been on some of the islands for even a longer period than sheep, for 

 they were introduced on Santa Catalina in 1827 (Bancroft, 1886), 

 and Farnham (1857) states that San Nicolas, San Clemente, and Santa 

 Barbara islands were densely populated by goats. 



Large areas of both San Nicolas and San Miguel have been rendered 

 completely barren by a combination of wind and water erosion. The 

 presence of too many sheep for the available pasturage has resulted in 

 the killing of grasses, forbs, and shrubs. Wind and rain have thus been 



