A Phytogeographical Classification of the North AmericanPacific Coast Based on Climate, Vegetation and a Floristic Analysis of Vascular Plants

[摘要] This study was designed to explore floristic variation along the Pacific coast from Cook Inlet, Alaska, to the southern tip of Baja California, Mexico. Data corresponding to 965phytosociological relevés (including 686 vascular plants) obtained by sampling 279 coastal siteswere examined. Using an objective classification system (Average Linkage Clustering), floristicdata acquired in fieldwork were related to the macroclimates of the study area. The registered taxawere grouped into phytogeographical elements, giving rise to a phytogeographical classification inwhich eight floristic provinces were distinguished. Floristic differences among provinces werecorrelated with palaeoclimatic and palaeogeographical events. The boreal and temperate provincesshow high percentages of broadly distributed elements, whose origins can be found in theBoreotropical or Arcto-Tertiary geoflora that dominated the Northern Hemisphere during theTertiary. The floristically richest provinces are the three that occupy the Mediterranean zone, sincethese provinces harbour elements of Arcto-Tertiary and Madro-Tertiary geofloras. The flora oftropical Baja California is characterised by a high number of taxa related to Neotropical flora,especially to those showing links with South America.

[学科分类] 植物学