Abstract||This thesis examines the effects of species, rainfall and soil type on tree biomass
regressions, as well as the effects of stand dominance and structure on stand biomass
regressions in north-east Australian woodlands. This was achieved by examining tree
characteristics and biomass relationships for a series of woodland monitoring sites
throughout the study area. This study utilised a modified data set from this permanent
monitoring site network to provide structural attributes for trees and communities of
varying composition in the grazed woodlands. These data were supplemented with
environmental data and tree harvest data sets.
Initially, the research reported in this thesis developed allometric and stand biomass
regressions for Callitris glaucophylla communities. This research also demonstrated
that changes in tree-form were not reflected in changes in the environment, nor did
such changes reflect changes in tree biomass regressions for three eucalypt species.
As a result, a common regression provides a robust estimate of total aboveground
biomass of eucalypt trees in the study area. Thus expensive destructive harvesting
can generally be avoided for minor eucalypt species. Finally, this study demonstrated
a successful methodology that described the stand structure of all the grazed
woodland sites based on tree heights. This methodology was developed to allow the
expansion of a single stand regression to estimate stand biomass across the entire
north-east Australian woodlands.
The findings demonstrated in this study, combined with the long-term data from the
permanent monitoring network sites, should enhance the estimation of carbon flux
within eucalypt communities of north-east Australia’s grazed woodlands.