The Ecology of the Mallee Outlier of Eucalyptus behriana F. Muell. Near Melton, Victoria

Abstract

An outlier of mallee vegetation occurs south of the Great Dividing Range in Victoria in a rain shadow region (annual rainfall approx. 500 mm) about 50 km west of Melbourne. A Eucalyptus behriana open-scrub with a sparse understorey of chenopods, mosses, lichens and some grasses occurs on solonetz soil on lateritized Tertiary sandy clays and on skeletal soils on Ordovician slates and sandstones. The dryness of the mallee site is probably exacerbated by the smaller rate of water infiltration and greater salinity of the solonetz soil under E. behriana compared with the solodic soil, in the moister area further north, under an open-forest of E. microcarpa.

The multistemmed habit of E. behriana appears to be partly genetically fixed. Hollow lignotuberous rings, filled to a depth of about 15-25 cm with brown, nutrient-rich humus, are common. Pattern analysis of the distribution of stems of E. behriana indicated strong clumping at about 9 m², due to the multistemmed habit, and weaker clumping at about 600 m², which correlated with the size of groups of dense, spindly individuals of E. behriana, resulting from a past phase of gap regeneration.