Above- and below-ground relationships, with particular reference to fine roots, in a young Eucalyptus globulus (Labill.) stand in southern Tasmania

Allometric relationships are important descriptors of tree form and are often used to scale physiological process measured at the individual tree scale to the stand scale. Despite their importance, there is little information relating above-ground form and function to below-ground form and function. In this paper, we present allometric relationships between above- and below-ground components for young (< 2 years old) Eucalyptus globulus, a globally important plantation tree species, in southern Tasmania, Australia. In particular, we examined relationships that exist between leaf area, above-ground biomass, fine root surface area and fine root biomass using destructive harvesting techniques. Fine roots (< 5 mm) were sampled spatially and temporally using sequential coring and scaled to estimate total fine root biomass and total fine root surface area using a weighting technique. There were strong relationships between leaf area and above-ground biomass with below-ground fine root surface area and biomass. These results are discussed in relation to the functional balance hypothesis for water transport in plants.