Water relations of jarrah ( Eucalyptus marginata) regeneration from the seedling to the mature tree and of stump coppice

Abstract

Water relations of jarrah ( Eucalyptus marginata Donn ex Smith) seedlings, ground coppice (advance growth), saplings, trees and stump coppice (sprouts) were investigated. Plant water status, indicated by shoot water potential and leaf stomatal conductance, improved with increasing size from seedling to the mature tree. Improved water status indicated that root systems were becoming more extensive and accessing a greater soil volume with age. Stump coppice had higher dawn water potentials, stomatal conductances and transpiration rates than other stages. The improved water relations of stump coppice are likely to be a consequence of taking over all or part of the large root system of the parent tree with the benefits of both access to a larger soil volume and a higher root/shoot ratio than in other stages. Ground coppice had higher stomatal conductances than the larger saplings. This may be evidence of higher root/shoot ratios roots in ground coppice (which are subject to recurrent destruction of the crowns of ground coppice by low intensity fires and other agents) than in the taller, less frequently damaged saplings.