Spread of Exotic Cordgrasses and Hybrids (Spartina sp.) in the Tidal Marshes of San Francisco Bay, California, USA

摘要: Four species of exotic cordgrass (Spartina sp.) occur in the San Francisco estuary addition to California native Spartina foliosa. Our goal was map location and extent all non-native estuary. Hybrids S. alterniflora foliosa are by far most numerous spreading rapidly. Radiating from sites deliberate introduction, hybrids now cover ca. 190 ha, mainly South Central Bay. Estimates rate aerial increase range a constant value an accelerating increase. This could be due proliferation hybrid clones capable rapid expansion having superior seed set siring abilities. The total coverage 195 ha other is slightly less than 1% Bay's tidal mudflats marshes. anglica has not spread beyond its original 1970s introduction site. densiflora over 5 at 3 patens expanded 2 plants 1970 42 one site Suisun floats on tide, giving it potential export this invasion throughout estuary, estuaries outside Golden Gate. We found isolated outer coast north Bay suggesting likelihood for populations others Pacific coast.