Quantification of Polypodium glycyrrhiza epiphyte loads on two common Pacific Northwest deciduous trees in relation to riparian zone proximity

Abstract

The Pacific Northwest is home to temperate rainforests that contain many vascular and non-vascular epiphytes. Non-vascular epiphytes have received the majority of research attention, whereas little research has been conducted on the Pacific Northwest’s most common vascular arboreal epiphyte, Polypodium glycyrrhiza. This study set out to quantify P. glycyrrhiza abundance on Acer macrophyllum and Alnus rubra and investigate how these abundances change with proximity to a riparian zone. It was hypothesized in this research that P. glycyrrhiza would show a preference for growing on A. macrophyllum individuals in comparison to the common hardwood species A. rubra, and that abundances would shift with streambed proximity. P. glycyrrhiza showed greater abundance on A. macrophyllum individuals compared to A. rubra, and on A. macrophyllum, a clear decline in abundance occurred with distance from the streambeds. There was no relationship found between streambed proximity and abundance of P. glycyrrhiza on A. rubra.