A multivariate approach to the problem of decline in vigour of Ammophila

Abstract

On stabilized sand dunes where sand deposition has ceased, Ammophila breviligulata Fern, declines in vigour, flowers less prolifically, and often remains vegetative. Many explanations for this decline have been put forward in the past. This study has chosen a comparative multivariate approach to address the problem.For this objective, 59 random 1-m2 quadrats were laid out over a young sand dune system near Port Franks, Ontario, on the southeastern shore of Lake Huron. In each plot six environmental variables (sand deposition, sand flux, number of annual species, number of perennial species, soil temperature, and the depth of the roots) and four plant characters of A. breviligulata (flowering percentage, shoot biomass, vegetative reproduction rate, and shoot density) were recorded. The resulting data matrices were subjected to canonical correlation analysis.The results revealed that, of the environmental variables, both sand deposition and root depth had strong relationships with shoot biomass (positive), flowering (positive), and vegetative reproduction rate (negative). Competition from annuals and perennials appeared a secondary factor in the decline of A. breviligulata. Flowering was rare in high shoot density sites with low levels of sand deposition and in low density sites with greater number of annual species.