An examination of ground cover for the assessment of ecosystem condition in the silver-leaved ironbark woodlands of the Desert Uplands

The thesis examines the ecosystem condition of silver-leaved ironbark woodlands within a spatial and temporal context. This relatively homogenous ecosystem, which covers over one million hectares within the Desert Uplands bioregion in Central Queensland, provides the ideal environment in which to examine relationships of condition variables across scales from site to landscape. The results establish that links exist between grazing pressures on ground cover and a number of ecosystem condition variables. The remotely sensed Ground Cover Index (GCI) was found to have significant relationships with field measurements. The current ecosystem condition assessment method using the Ground Cover Disturbance Index (derived from the GCI) is assessed and improvements are suggested that allow climatic effects to be accounted for to ensure the index better reflects ecosystem functionality. The GCI, together with field ground cover measurements are explored to assess ecosystem condition with respect to field measurements of avian and plant diversity. The GCI was found to have a significant relationship with perennial grass cover. Perennial grass abundance and richness were found to have significant relationships with ground cover and are recommended as indicators of ecosystem condition. Avian groups as indicators were less effective with both strong positive and negative relationships with ground cover existing within the groups. The bird habitat assemblage group shows promise for further investigation for the assessment of ecosystem condition. Finally, linear mixed effect modelling established the relationship between ground cover and climate and grazing explanatory variables; the effects of each variable were qualified and the predictive power of the model was validated against ground cover measurements.