An assessment of the relationship between tree-ring counts and basal girth of high-altitude populations of Eucalyptus pauciflora (Myrtaceae)

Abstract

We investigated the relationship between the number of growth rings (a surrogate for approximate age of stems) and basal girth for Eucalyptus pauciflora (Maiden & Blakely) L.A.S.Johnson & Blaxell. Using basal-girth measurements and growth-ring counts obtained from trees felled on ski slopes at three Victorian alpine ski resorts, as well as seedlings destructively sampled from near the tree line on four summits, we modelled the relationship between growth rings and basal girth by using simple linear and non-linear regression methods. We compared our data to growth-ring–basal-girth data collected from low- and high-altitude E. pauciflora woodland stands in Kosciuszko National Park. The relationship between the number of tree rings and basal girth at Victorian sites was non-linear (growth rings = 3.62 × girth0.63, R2 = 0.96). In general, the Victorian and Kosciuszko datasets were in broad agreement, although caution is required when attempting to estimate the age of trees with >115-cm girth. We suggest that the model we have developed can be combined with dendrological techniques to estimate the age of older trees accurately.