Low-rainfall species trials in New South Wales Part 1: Survival, growth and form over the first 57 months.

A trial of potentially commercial tree species, planted over 45 sites across the 500-800 mm annual rainfall zone of New South Wales, was assessed for survival and height at ages 10-57 months, and for stem form at 57 months. The sites were located from the North-west Slopes and Plains to the South-west Slopes, covering about six degrees of latitude, and were designated as occurring in North, Central or South region. The plantings overall included nine species, with six of these planted at each individual site. A mixed-model analysis of variance was applied to height and survival data for all ages. Species, age and species region inter action effects were highly significant for both traits, while region was also significant in the case of survival. High survival rates of over 80% were maintained for 57 months across sites by Eucalyptus camaldulensis, E. sideroxylon and Saltgro hybrid eucalypt clones. Survival of Pinus pinaster and Acacia mearnsii declined rapidly within 2-3 y to 17-34% overall. Pinus pinaster survived especially poorly in the North region, possibly due to clay soils at several sites. Frost was considered to have reduced survival of two spotted gum species (Corymbia maculata and C. citriodora subsp. variegata) in the North and Central regions relative to the South. Overall superior species for height included E. camaldulensis, C. maculata, Saltgrow clones and A. mearnsii (4.8-5.5 m at 57 months). Pinus pinaster was much the poorest (overall mean 1.6 m), growing best in the South region. Eucalyptus cladocalyx of southern origin and E. argophloia of northern origin appeared, from limited data, to be equally adapted to the North and South regions. From analyses of the proportions of trees with no forking and with superior stem straightness, species, region and species region effects were significant. Pinus pinaster tended to have the straightest and leastforked stems, while E. cladocalyx, represented by a known poor provenance, was poorest for these traits. The spotted gums also had high proportions of straight trees (75-77%) but had somewhat lower numbers of unforked trees. Proportions of unforked trees were significantly greater in Central compared with other regions; the reason for this is not known.