Salt tolerance and functional traits of Morella pensylvanica and Vaccinium angustifolium differ between coastal forests and barrens in Nova Scotia

Climate change is increasing storm intensity and sea level rise, exposing coastal ecosystems to higher marine salt loads through sea spray and storm surges. Atlantic coastal habitats such as barrens (heathlands) and forests are dominated by shrubs that play key roles in ecosystem structure and function, yet the salt tolerance and functional responses of many species remain poorly understood. This study examined variation in leaf functional traits and soil chemistry across coastal salinity gradients in Nova Scotia, Canada, focusing on two dominant shrub species, Northern bayberry ( Morella pensylvanica ) and lowbush blueberry ( Vaccinium angustifolium ). Individuals were sampled in forest and rock barren habitats at two distances from the shoreline. We measured traits related to water relations, ion regulation, and nutrient status: stomatal conductance, specific leaf area (SLA), leaf thickness, leaf dry matter content (LDMC), and leaf concentrations of sodium (Na), potassium (K), calcium (Ca), nitrate (NO₃), electrical conductivity (EC), and pH. Soil samples were analyzed for comparable chemical properties. We used multi-factor ANOVA and principal components analysis to assess variation by species, habitat, and distance from the Atlantic Ocean shoreline. Coastal barrens had higher soil salinity than forest sites, and plants in barrens displayed stronger variation in structural and chemical traits. Morella pensylvanica exhibited greater variation in morphological and chemical traits and maintained lower, more stable Na/K ratios, consistent with greater salt tolerance. In contrast, V. angustifolium showed lower stomatal conductance and higher Na/K ratios in exposed sites, suggesting greater sensitivity to salinity. Our findings suggest that coastal salinity gradients and habitat differences influence functional trait variation in these abundant shrub species, and that forest habitats may reduce exposure to marine salt inputs. This research contributes to our understanding of habitat-specific stress responses and may inform coastal conservation efforts by identifying species with greater tolerance to marine salt exposure.