ibclogo XVI International Botanical Congess


Abstract Number: 5909
Poster No. = 1001


THE VASCULAR FLORA OF SAN NICOLAS ISLAND, CALIFORNIA.


Steven A. Junak, Santa Barbara Botanic Garden, Santa Barbara, CA 93105


San Nicolas Island, situated 98 km from the mainland, is the most isolated of the 8 California Channel Islands. A total of 272 vascular plant taxa comprise the island=s flora, but only 52@ of these taxa are considered to ber native. The native plants represent 42 families, 93 genera, and 139 taxa. The largest families are Asteracea, Fabaceae, and Poaceae, the largest native geenra include Atriplex, Microseris, Opuntia, and Trifolium. For its size, San Nicolas Island has the most depauperate flora of the 8-island archipelago, presumably due in large part to its isolation and relative lack of ecological diversity when compared to adjacent islands. In addition, profound changes in the composition and distribution of the island's vegetation and flora have occurred since the early 1900s, due to past grazing, habitat disturbance, and the arrival of non-native plants. At least 24 of the island's native plant taxa are considered to be rare by the California Native Plant Society. Seven native taxa, including 2 which may have been restricted to the island, have not been seen for about 100 years and may have been extirpated.


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