| The Gulf of St. Lawrence Aster (Symphyotrichum laurentianum (Fern.) Nesom) (Asteraceae) is a rare, halophytic salt marsh plant endemic to Atlantic Canada. Folivory (herbivory by leaf area removal) is known on this species, but its impact on plant fitness has not been further studied. I examine the effect of folivory on Sym. laurentianum, comparing it to impacts of salinity by investigating their effect on seed set and survivorship. My results suggest that folivory is less important that salinity, which had strong, significant effects on fitness. I then examine these results in the context of current knowledge on the effects of herbivores on rare plant populations, reviewing information on 23 rare plants and 38 insect herbivores; my findings suggest that population-level effects of herbivory on rare plants remain poorly understood. I then suggest general approaches to address this issue, and stress the importance of including herbivory in rare plant conservation. |
