Solidago sempervirens (seaside goldenrod).

Solidago sempervirens is a herb native to North America that has been introduced as an ornamental and to combat soil erosion and stabilize dunes. This species is highly tolerant of both saline soils and salt spray and can be found growing in coastal thickets, salt marshes, sand dunes and the banks of estuaries and lakes, but also in grasslands, disturbed sites, forest edges and along roadsides. This species is adapted to grow in a wide range of climates (from tropical to a humid continental and temperate oceanic climates) and produces large amount of wind-dispersed seeds, which are features that may facilitate its spread into new habitats. S. sempervirens also produces allelochemicals that suppress the establishment and growth of other plant species. Currently, it is listed as invasive in the USA, Japan, the Dominican Republic, the Azores and Australia.

Impacts of salinity and simulated herbivory on survival and reproduction of the threatened Gulf of St. Lawrence Aster, Symphyotrichum laurentianum

Halophytic plants may experience joint, and potentially interacting, effects of salinity and herbivory on their survival and reproduction. We investigated the impacts of salinity and (simulated) herbivory on fitness in the Gulf of St. Lawrence Aster ( Symphyotrichum laurentianum (Fernald) Nesom; Asteraceae). In natural populations, this species experiences varying soil salinity and spill-over herbivory from insects associated with neighbouring seaside goldenrod ( Solidago sempervirens L.). We subjected S. laurentianum individuals to three levels of simulated herbivory (0%, 20%, and 40% leaf-area removal) and three levels of salinity (0, 10, and 20 g·L–1) in three runs of a growth-chamber experiment. The effects of salinity and herbivory were always additive. Salinity consistently and strongly reduced survivorship, by as much as 80% at 20 g·L–1 salt, but significantly affected the seed set of survivors in only one run. Herbivory reduced survival significantly in one run (by 42% at 40% leaf-area removal) and reduced seed set of survivors (by 36% at 40% leaf-area removal) in another. While both stresses can have important effects on S. laurentianum fitness, the effects of salinity were more consistently strong than were the effects of herbivory, for both survival and seed set.