From salmon to salmonberry: The effects of salmon‐derived nutrients on the stomatal density of leaves of the nitriphilic shrub Rubus spectabilis

Nutrients derived from the carcasses of Pacific salmon have been shown to have wide-ranging effects on riparian systems. These include changes in community species composition and an increase in leaf nitrogen concentration, with the latter effect pronounced in the nitriphilic shrub Rubus spectabilis(salmonberry). Experimental work with other species has shown that leaf stomataldensity increases in response to nitrogen fertilization. We predicted that the stomataldensity of salmonberry leaves would vary directly with the density of spawning salmon in salmonberry leaves collected from 16 streams in the vicinity of Bella Bella, on British Columbia’s central coast. We estimated the stomataldensity along each stream, and quantified stream characteristics, including the number of spawning salmon (Oncorhynchus spp.), canopy cover, stem density and soil moisture. We found that salmon have both direct and indirect effects on stomataldensity, the latter mediated by canopy cover and stem density. Salmonberry stomataldensity increased by 1.12 stomata per mm 2 (~0.5%) for every kg of salmon per metreof stream. Over the range of salmon densities observed (1.8–49.0 kg per metreof stream), stomataldensity increased by almost 45 mm − 2 , or more than 20%. These data confirm that the stomataldensity in salmonberry responds positively to the opportunity for greater productivity provided by salmon carcasses. The data provide insight into the physiological and morphological processes supporting nitrogen uptake, which in turn influences plant community composition. A plain languagesummary is available for this article.