Vegetationndash;elevation correlation in two dyked marshes of northeastern Vancouver Island: a multivariate analysis

摘要

Vegetation ndash; substratum elevation relationships in the Kokish and Cluxewe tidal marshes on northeastern Vancouver Island were examined using principal components analysis, canonical correlation analysis, and multivariate analysis of variance. Both marshes have similar undyked vegetation with low-elevationCarex lyngbyeidominated stands and higher elevation mixed-grass swards ofFestuca rubra,Deschampsia cespitosa,Hordeum brachyantherum, andAgrostis stolonifera. Dyked areas were less comparable in their vegetation as a result of a variety of disturbances in the past. Elevation showed a stronger connection with Continuous compositional change in undyked than in dyked areas, but less than half of the total vegetation variation was explained. Plant community classifications, based on aerial photographs, accounted for high proportions of the total vegetation variation (87ndash;99) and residual variation (62ndash;97) remaining after the "effect of elevation" had been removed from the vegetation data, using regression analysis. This suggested that the plant communities recognized are distinct units but that factors unrelated to elevation are mainly responsible for their formation.