Eucalyptus occidentalis

Cultivation Details

Eucalyptus occidentalis is native to the Mediterranean climate of southwestern Australia, where it is found at elevations up to 100 metres. Rainfall occurs mainly in the winter months, with a mean annual rainfall within the range 380 - 760mm and a dry season of up to 7 months. The mean maximum temperature of the hottest month is 36 - 38°c; mean minimum temperature of the coldest month is 0 - 2°c, and there are generally around 2 - 20 frosts a year^[1]. When dormant, the plant can survive temperatures down to about -3°c, but young growth is more tender and can be severely damaged at 0°c^[2]. Requires a sunny position, succeeding in a range of heavy to medium-textured soils of low to moderate fertility^[2]. Found mainly on clay soils in the wild^[1]. Some provenances are tolerant of saline soils^{[2, 3]}. Prefers a pH in the range 6.5 - 7.5, tolerating 6 - 8.5^[2]. Established plants are very drought tolerant^[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]. The tree is rather slow-growing, but can reach a height of 5 metres in 3 years^[2]. Wood production potential is 3 - 8 cubic metres per hectare/year^[2]. A valuable eucalypt for planting because of its potential to provide a crop on dry, marginal lands in Mediterranean-type regions^[1]. In Israel it prefers clay soils and has proved to be resistant to heat, prolonged drought, high salinity and calcium carbonate content of the soil. It also stands prolonged flooding, even with saline water^[1]. In Italy, on the other hand, it has proved to be highly susceptible to frost damage. It is of rather poor form but has shown high survival and good adaptation to difficult, compacted clay soils in dry areas of Calabria (winter rainfall 600-700 mm) It coppices well. Although the yields in the first rotation are low (mkt 1.5 to 6.0 cubic metres per hectare/yr at age 12 according to site quality), the plantations also fulfil an important protective function on difficult sites on slopes subject to flooding^[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^[4]. 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^[4].