Groundwater dependent ecosystems in Australia : Case study 2 : riperian vegetation of the Daly River

D. Eamus, T. Hatton, P. G. Cook and C. Colvin CSIRO,

Dry season flows are dominated by groundwater input from limestone aquifers underlying the Daly River catchment. A project was initiated to establish the environmental water requirements of the vegetation of the Daly River. The aims of this study were to describe the climate and topography of the Daly River and its riparian vegetation; to characterise patterns of soil water availability, leaf water potential and water use of dominant tree species; and to determine the relationship among tree water use, species and tree size. Conclusions were that trees were accessing water from layers deeper than 1m and that groundwater contribution to water transpired by trees was highly variable. Some tree species, located close to the river, are obligate groundwater users, while species further from the river are facultative groundwater users. Despite large associated errors the estimate of groundwater use was valuable for resource planning..