In the tropics and Southern Hemisphere, plantation forestry of exotic tree species contributes substantially to the international paper and pulp industry. The most widely planted trees are species of Pinus, Eucalyptus and Acacia (Wingfield et al. 2002). In South Africa, Eucalyptus species comprise approximately 39% of the 1 333 562 ha of plantation forestry (FES 2006).Eucalyptus species have been planted in South Africa for more than a century beginning with the planting of E. globulus in the Cape Colony in 1828, which soon stimulated interest in other members of the genus for new introductions (Poynton 1979). More recently, eucalypts have been used extensively for the production of sawtimber and pulp and paper (Swain and Jones 2004), stimulating wide-ranging tree improvement activities in South Africa. New species and provenances are regularly introduced into the country and evaluated for their potential use in the forestry industry .Eucalyptus plantations in South Africa are found over a wide range of different climatic zones, with the humid, warmer temperate and subtropical regions comprising an important part of this area. Traditionally, E. grandis has been the most extensively cultivated hardwood species in these regions because of this species' rapid growth and acceptable wood properties (Poynton 1979). During the last two decades, however, commercial forestry in South Africa has expanded into mid-altitude summer-rainfall sites that are drier and warmer, or drier and colder, than so-called traditional forestry sites. These areas are not suitable for optimum growth of E. grandis and are generally referred to as 'low productivity' sites. The mean annual temperatures (MATs) of less than 18 °C and altitudes above 1 050-1 300 m, depending on latitude, are not suited to the planting of E. grandis (Swain and Gardner 2003a), as this species displays extensive susceptibility to drought-and cold-induced mortality (Darrow 1983). These mid-altitude sites are also not suited to the growth of E. nitens provenances that usually perform well at altitudes greater than 1 350 m, but do not grow well on these lower-altitude sites.Better-performing and better-adapted species and provenances are therefore required for sites too low for Eucalyptus grandis is cultivated extensively in the humid, warmer temperate and subtropical regions in South Africa. With forestry expanding into mid-altitude drier and warmer, or drier and colder, sites the search to identify reasonably well-performing species/provenances for such 'low productivity' sites has extended to summer-rainfall provenances of E. globulus subsp. bicostata, which is closely related to E. globulus, a species known to have superior kraft pulping. Seed from New South Wales, Australia, provenances Narrow Neck Ridge, Nullo Mountain (West) and Nullo Mountain (North) was established in provenance/progeny trials on four sites in South Africa (Windy Gap, Enon, Petrusvlei and Speenkoppies). Eucalyptus globulus and E. globulus subsp. maidenii were the internal controls. Trials were p...