Among-Tree Variation in Leaf Phenology and Morphology and Its Correlation with Insect Performance in the Mountain Birch

Abstract

We studied variation in leaf morphology and phenology in a population of the mountain birch (Betula pubescens ssp. tortuosa) in northernmost Finland over two summers. We tested tree quality with bioassay using several leaf-eating insect species to study the impact of plant variation on herbivore performance. Leaf size and phenology varied considerably between years. Differences among trees were significant, but undividual trees retained their leaf-character-ranking within and between seasons. Positive correlations between tree height and leaf size and differences in bud growth patterns indicate that the mountain is genetically related to the dwarf birch, B. nana (...)