Life-span of leadwood trees

Abstract

Radiocarbon analyses on 16 specimens of the Leadwood tree, Combretum imberbe, showed that they live for several hundred years. The oldest specimen was more than 1000 years old when it died and had an extremely slow radial growth rate of 0.33 mm yr(-1), while a tree in a more favourable moisture position had a growth rate of 2 mm yr(-1) and lived for some 300 years. Although a trunk diameter of 2.2 m was recorded, most trees die before their trunks reach a diameter of much more than 1 m and well before they reach an age of a thousand years. The dead trees can remain upright in the landscape for as much as 80 years, while dead logs survive in the environment for as long. In view of the fluctuations in the radiocarbon level, especially over the five centuries prior to AD1950, it is clear that three or more radial samples from the bole are necessary for determining the life span of slow-growing trees.