LEAF MORPHOLOGICAL AND ANATOMICAL VARIATIONS OF PAPER BIRCH POPULATIONS ALONG ENVIRONMENTAL GRADIENTS ACROSS CANADA

Abstract

Leaf morphology and anatomy have been found to vary considerably among tree species, and leaf characteristics have widely been used for analyzing plant growth and resource use strategies because of their structural adaptation to withstand environments. Considering the changing climate projections, early-successional, broad niched species like paper birch (Betula papyrifera Marsh.) are expected to increase dominance due to a zonal shift of natural vegetation and/or open gaps within the current vegetation zones. Hence, it is important to understand factors such as leaf characteristics that enable these pioneer species to inhabit a wide geographic range and their increasing dominance. Paper birch is a pioneer tree species in North America that inhabits wide climatic and geographic gradients; in addition, the species has developed different leaf morphology and anatomy that have allowed paper birch to adapt to diverse habitats. This study examines how the leaf characteristics of paper birch vary under uniform and stressed environments. The major objectives were (a) to investigate leaf characteristics variations in paper birch populations grown in uniform environmental conditions as in a greenhouse and a common garden; (b) to correlate between leaf characteristics and paper birch’s environment of origins; (c) to investigate leaf characteristic variations in paper birch populations grown under different carbon dioxide concentrations [CO2] and soil water levels to determine the relationship between leaf characteristics and individual or interacting effects of [CO2], water levels and populations; and (d) to analyze the relationship within and between leaf morphology and anatomy of the birch populations.