Eucalyptus dunnii

Cultivation Details

Eucalyptus dunnii is native to the subtropical climate of eastern Australia, where it is found at elevations from 150 - 800 metres. Summers are hot and wet whilst winters are mainly dry with a dry season of three months. Mean annual rainfall is within the range 1,000 - 1,500mm; mean maximum of the hottest month is 27 - 29°c; mean minimum of the coldest month is 8°c, and frosts are generally few and light^[1]. There is a report, though, that trees in a plantation in Brazil have proven to be surprisingly frost-tolerant, surviving several degrees of frost without damage^[1]. Eucalyptus species generally require a sunny position, succeeding in a wide range of well-drained, circumneutral soils of low to moderate fertility^[2]. The plant develops a lignotuber - this is a woody tuber that starts to develop near the base of seedlings and can become massive in the mature plants of some species. It possesses embedded vegetative buds, allowing the plant to regenerate following crown destruction, for example by fire^[3]. This is one of the fastest growing trees in Australia, possibly the fastest. If papermakers will accept it and if seed supplies can be developed, it should be one of the most popular plantation species for summer-rainfall areas with a rainfall of 1,200mm or more. An additional advantage of the species is its resistance to cold, which has only been tested in the last decade. In tests in the United States it has been found to be one of the most cold-resistant eucalypts. In a recent bout of freezing weather in Brazil which damaged the coffee crop and some eucalypt plantations, this species was not injured^[1]. Eucalyptus species have not adopted a deciduous habit and continue to grow until it is too cold for them to do so. This makes them more susceptible to damage from sudden cold snaps. If temperature fluctuations are more gradual, as in a woodland for example, the plants have the opportunity to stop growing and become dormant, thus making them more cold resistant. A deep mulch around the roots to prevent the soil from freezing also helps the trees to survive cold conditions^[2]. Many members of this genus are remarkably adaptable however, and there can be a dramatic increase in the hardiness of subsequent generations from the seed of survivors growing in temperate zones^[2]. Whilst most Eucalyptus species, grown in small numbers outside their native range, can be an attractive and useful addition to the landscape, certain species (including this one) are more problematic. When grown in monocultures, especially outside their native range, they can become an environmental disaster. They are voracious, especially in their use of water; they are allelopathic, inhibiting the growth of the native flora; they reduce habitats for native fauna; and encourage the worst possible attitudes to land use and conservation^[2].