
Growth decline with age in trees is hypothesized to be an effect of carbon limitation. By assessing carbon reserves and isotopes at different ontogenetic stages in the deciduous broadleaf tree Nothofagus pumilio (lenga beech) in two forests in southern Chile,  Piper and Fajardo test this hypothesis and find that carbon reserves do not vary with tree age. The results thus suggest that carbon limitation is not the ultimate mechanism causing the age-related decline in tree growth.