Field comparison of δ15N values and growth of alder provenances and species

Abstract

Abstract Growth and δ15N values in the leaves of three alder species (Alnus glutinosa, A. cordata, and A. rubra) originating from various locations were examined. Natural 15N abundance was used to screen the N2 fixing capacity of these plants. We compared 4-y-old trees growing on two different soil types at two densities. Our results showed that A. rubra did not grow at a French site (Miribel) and the performance of the other alders was clearly controlled by both the origin and soil properties. In a sandy soil, significant differences in the δ15N values were observed in the different provenances of A. glutinosa without any effect on their growth. Genetic variability among alder genotypes was detectable only in a soil with low fertility at a high tree density. Differences in growth and δ15N values disappeared when the tree density was low or when the soil was fertile. Our results indicate that the difference in adaptation of species and provenances to local climatic and soil conditions must be taken into a...