Adaptive variation in growth, phenology, cold tolerance and nitrogen fixation of red alder (Alnus rubra Bong.)

► Red alder families differ in N nutrition, growth, phenology, and cold tolerance. ► Differences in climate of family origin explain among-family trait variation. ► Phenology and cold hardiness are most tied to family climate of origin. ► A trade-off between growth and cold hardiness exists in red alder. ► Families from cool, moist regions have the highest relative N fixation.