Flowers, Seed and Propagation
Flowers are white, in clusters of 7–11, generally from December to February, although flowering time depends on locality: summer in the south; autumn in the north-west; and winter-spring in the northeast of Australia. Eucalyptus camaldulensis flowers heavily every two or three years, depending on the season.
Seed collection is best from March to September, although collection times may vary due to regional and seasonal variability. The first seed crop from young trees can occur by age three.Seeds are cuboid or pyramidal, with smooth face 1–1.5 mm long; yellow to brownish yellow, with two seed coats (other red gums have a single dark brown to black seed coat). There are between and 1160 viable seeds/g. Refrigerated seed will keep for several years and no pre-sowing treatment is required. When propagated under warmer conditions, seedlings can reach plantable size in 6–8 weeks, compared to 4 months iculn cooler southern areas. Improvements in root/seedling growth are possible when using nursery containers coated with copper carbonate, particularly when raising seedlings for dryland afforestation.
Silviculture and Management
Eucalyptus camaldulensis can be successfully established with similar preparation and treatments as many other eucalypts, ensuring good weed control prior to planting. Seedlings can be either hand or mechanically planted. To allow machinery to be used, a spacing of 3–5 m between rows is required. When pulpwood production is the principal objective, a spacing of 3 m x 2 m (1667 trees/ha) is often used. Wider spacing of 4 m x 2 m (1250 trees/ha) or 5 m x 2 m (1000 trees/ha) are recommended when larger trees are required. When growing for firewood, direct seeding at 250 g/linear km (approximately 750 g/ha) with rows 4 m apart is an option. Wider spacing between rows facilitates mechanical cultivation for weed control. Sow early to mid spring in the south to maximise soil water availability and to avoid heavy frosts.
Silviculture varies between northern and southern provenances as planting time should coincide with rainfall. Wider spacing and shorter rotation may be considered in warmer regions with weed control remaining critical, especially in early years. Progressive thinning and pruning is required for clearwood production.
All provenances coppice well for five or more rotations; good coppicing may be increased by felling trees outside the dry season with a cleanly cut stump and minimjum bark damage.
Good timber can be achieved in 30 years in well managed plantations and within 10 years for onfarmuse (posts/firewood). Prices received are variable and dependent on local market conditions.
Eucalyptus camaldulensis is not commonly planted for wood production in Australia due to its form and provenance variability. Large variation exists in growth rate and in tolerance to salinity, drought, frost and insect attack. It is therefore very important to select the correct provenance for the purpose and location for which the species is being grown. In the seasonally dry tropics, provenances like ‘Petford’ (QLD) and ‘Katherine’ (Northern Territory) are the most sought after for breeding programs. For southern temperate Australia, the best performing provenances (in terms of survival and growth) for saline and seasonally waterlogged conditions include ‘Lake Albacutya’ and ‘Douglas River’ (VIC) and ‘Silverton’ (NSW). In Western Australian trials, ‘Laura’ (SA) has performed well.
Qualifying Tolerance Information
Moderately salt-tolerant, although there is considerable provenance variation for tolerance to salinity and water logging. Expect reduced growth about ECe 5 dS/m and reduced survival above about ECe10 dS/m. (ECe refers Electrical Conductivity of a saturated soil paste extract).
Tolerates extremes of heat and cold and great variation in rainfall; has a moderate to high drought tolerance. Often occurs naturally along watercourses, so low rainfall in its natural habitat does not always indicate the extent of drought tolerance. It prefers access to a water table or periodic flooding and will withstand long periods of flooding.
Frost tolerance varies with provenance, however very good tolerance, even when young, has been found in some inland provenances; up to 20 frosts a year may be experienced in southern and inland areas.
A recent revision of climatic requirements for establishment of Eucalyptus camaldulensis for farm forestry suggests that a mean annual rainfall of 400-2000mm is needed and that particular care should be taken when planting in lower rainfall environment to ensure that local conditions are suitable and appropriate planting densities are used.
Lynne McMahon Farm Forestry Extension Officer
Brendan George Industry Leader Bioenergy & Private Forestry Industry Development, Agriculture & Forestry
Robyn Hean Natural Resource Economist