Seventeen Palms: A Declining Desert Fan Palm (Washingtonia filifera) Oasis in Anza-Borrego Desert State Park

摘要

A population of Washingtonia filifera at Seventeen Palms in California's Anza-Borrego Desert State Park, was analyzed five times over a period of 104 years. A dramatic shift in structure from juvenile to adult dominance was recorded. With only two tentative recruits to the population since 1984, W. filifera seems likely to be extirpated at Seventeen Palms if existing conditions persist. The near elimination of population recruits is most likely due to diminished spring flow. A decline in precipitation, increase in frequency and duration of drought and crustal displacement from earthquakes are possible factors in the reduction of moisture availability. Rising temperatures contribute to the moisture deficit.