A phytosociological survey of the dune forests of the Pacific Northwest

Abstract

We report on phytosociological survey of the forests dominated by Pinus contorta var. contorta and/or Picea sitchensis that thrive on the Pacific Northwest, between the Strait of Juan de Fuca in Washington and Cape Mendocino in northwestern California. Through tabular and average linkage cluster analyses, 198 relevés taken at 69 sites were classified. Diagnostic tables, climatic, edaphic, and biogeographical data were used to establish floristic affinities among the seven identified associations and to interpret their distributions in psammophilous and zonal gradients, as well as their syntaxonomic position in the Temperate North American class Tsugetea mertensiano-heterophyllae. Four associations are described here for the first time: Arctostaphylo uva-ursi-Pinetum contortae, Carici obnuptae-Pinetum contortae, Morello californicae-Piceetum sitchensis, and Pseudotsugo menziesii-Pinetum contortae.

Keywords:

• Braun-Blanquet approach
• North American forests
• plant association
• sand dune vegetation
• syntaxonomy

Acknowledgments

This study was supported by grants from the Agencia Española de Cooperación Internacional para el Desarrollo (A/024250/09) and Franklin Institute of North American Studies (UAH). The authors thank Ana Burton for help with the English translation.