Using the pressure-bomb to construct pressure-volume curves, a cellular basis of differential drought resistance was found between Callitris columellaris (F. Muell), Eucalyptus melliodora A. Cunn. ex Schauer, and Eucalyptus microcarpa Maiden. Between these three species differences were found in bound water, relative water content and water potential at zero turgor, osmotic potential at full turgor and bulk modulus of elasticity. It is suggested that these parameters showed C. columellaris to be the most, and E. melliodora the least drought resistant of the three species.Preliminary studies also showed that drought hardening may involve an increase in bound water content, dry weight: turgid weight ratio and a decrease in osmotic potential at full turgor and water potential at zero turgor.

The vegetation in the rain shadow areas of the Snowy River region was studied. Five distinct woodland communities were recognised from a numerical classification, a community dominated by C. columellaris at lower altitudes on north and west aspects, three mixed C. columellaris/E. albens communities which are also aspect and altitude dependent, and a higher altitude, cool aspect, E. albens dominated community. Although C. columellaris and E. albens occupy separate niches, they compete strongly. Contrasting dispersal and germination behaviour between the two species may explain the current distribution and structure of these woodlands.

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