Intraspecific variation in nitrogen status and photosynthetic capacity within mountain birch populations

Abstract

The relative variation in leaf nitrogen concentration and photosynthetic capacity among individuals and sites are compared for mountain birch populations (Betula pubsecens Ehrh. ssp tortuosa (Ledeb.) Nyman).Leaf nitrogen concentration and photosynthetic capacity showed significant differences among individuals; 35 and 26% of the total sum of squares respectively, was attributable to differences among individuals. Two measures of leaf morphology also showed differences among individuals (35–58% of total variation). The variation attributable to site differences ranged from 13% (leaf shape, P = 0.11) to 36% (leaf N concentration and photosynthetic capacity, P≤0.01). Of the variation in photosynthetic capacity, 51% was related to leaf nitrogen concentration. Possible causes for and consequences of the differences found are discussed.