Hydrologic inferences from tree-ring studies on the Hawkesbury River, Sydney, Australia

• Autores: Daniel M. Martens
• Localización: Geomorphology, ISSN 0169-555X, Vol. 8, Nº 2, 1993, pág. 147
• Idioma: inglés
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• Resumen

  • Introduced Salix trees in Australian alluvial environments can be used to make a number of hydrologic inferences. Dendrochronological studies along the Hawkesbury River near Windsor suggest that the Salix growth form and annual growth-ring variability are closely associated with the local hydrologic regime. Detailed analyses of 33 trees showed that tree growth is suppressed close to water and increases with height above mean low stage levels because of the decreasing influence of flooding. Alluvial levels contain discrete vegetation patterns and growth characteristics that are not explained by variations in soil and climate. Growth of Salix in thickets on low in-channel benches is flood limited with fitted exponential growth curves having positive or zero slopes. The high in-channel bench contains vegetation influenced by flooding but growing according to classical exponential decay functions. Trees on floodplain levees show full canopy development and the most rapid growth because of fertile soils, the high availability of water, and limited influence of floods overtopping levee tops. Elevation and tree-growth relations are used to develop a relation between growth and flood frequency. This is applicable to catchments of similar size, soil type, and climate. Analyses of tree form and root distribution indicated that dendrochronological techniques may be used to determine the minimum land surface age and rates of accretion around the tree bole in alluvial areas of southeastern Australia.