Plant response to heterospecific neighbor removal and nutrient addition in a subarctic coastal dune system (northern Québec, Canada)

Abstract

Removal of heterospecific neighbors and addition of nutrients were performed in the field, on a subarctic coastal dune system in northwestern Québec (Canada), to test for the significance of interspecific interactions and nutrient availability on plant performance. Elymus mollis and Lathyrus japonicus, the major species found on the second ridge (approximately 150 years old) of the dune system were studied. Nutrient addition increased the performance of both E. mollis and L. japonicus. However, heterospecific neighbor removal had no significant effect on either species. Most importantly, there were no significant interactions between heterospecific neighbor removal and nutrient addition in any of the analyses of variance performed on the response variables, for either one of the two species. These results suggest that nutrient availability does not influence species interactions in the system, and that limiting abiotic conditions may restrict plant-plant interactions even on somewhat older ridges. Temporal and/or architectural niche segregation between the two species studied may also explain, in part, the absence of biotic interactions.