Indicators of population viability in red spruce, <i>Picea rubens</i>. I. Reproductive traits and fecundity

Abstract

Red spruce (Picea rubens Sarg.) has experienced a substantial decline across most of its range in eastern North America over the past century and probably also in the disjunct Ontario populations where it now occurs only in small isolated stands. Measurements of cone and seed traits from natural populations were used as indicators of the reproductive and genetic status of red spruce across the northern margins of its range in Canada. Cone and seed traits were quantified to provide reproductive benchmarks for assessing and monitoring population viability. Reduced fecundity and seedling height growth were observed in some of the smallest Ontario populations, suggesting some inbreeding depression in both vegetative and reproductive components of fitness. Nevertheless, the reproductive status of these small isolated Ontario populations compared favorably with the much larger, more extensive Maritime populations in Nova Scotia and New Brunswick. Significantly higher proportions of aborted (nonpollinated) seeds...