Eucalyptus - part 1: species with forestry potential in the British Isles

The genus Eucalyptus is part of the Myrtaceae family and contains over 700 species with all but two tropical species being endemic to Australia (Brooker, 2000). The wide range of habitats present in Australia has fostered a high degree of genetic variation both between and within species (Florence, 2004). Starting in the mid-19th century, a wide range of Eucalyptus species have been planted in many countries, including Britain, facilitated by improved understanding of the taxonomy of the genus and increasing availability of seed of well-defined origins (Zacharin, 1978). Until the 1950s interest in Eucalyptus in the UK was focussed on their arboricultural potential on estates and in gardens. The performance of 19th century plantings were comprehensively reviewed by Elwes and Henry (1906-13), and again by Martin (1948) and MacDonald et. al. (1957). Trial forestry plots were first established in Ireland in 1909 (Mooney, 1960), although not until the 1950s in the UK (MacDonald et. al., 1957). Plantings made after 1950 were reviewed by Evans (1980). All these plantings generated interest because of the fast growth of many species. They also highlighted that most species are insufficiently hardy to survive for long in Britain, especially in colder inland areas. Nevertheless, a few species have proved to be sufficiently hardy to survive extremely cold winters. Some individuals of a small number of species have proved to be long-lived, and have grown to large dimensions. The oldest specimen still living is probably an Eucalyptus urnigera, recorded as having been planted in 1881 in the grounds of Stonefield Castle, Argyll (TROBI, 2015). The Tree Register of the British Isles (TROBI) database provides a host of other examples, some of which have outstanding form as well as impressive dimensions. In recent years there has been increased interest in using woody biomass for energy, and in alternative species for UK forestry due to the concerns about the impact of climate change (Read et. al., 2009), and due to the risk of growing traditional forestry species because of new pests (Logan et. al., 2003) and diseases (Sturrock et. al., 2011). This has led to renewed interest in the use of certain Eucalyptus species in forestry in Britain. Some very interesting and impressive trial stands have resulted, as well as poorly-established and failed plantings. In this article we review the Eucalyptus species that appear to have potential for forestry in Britain. In the next issue we will evaluate forestry trials and recent plantings in Britain, and prospects for more widespread use of Eucalyptus species (Purse and Leslie, 2016)