Silvertop
Silvertop (Eucalyptus sieberi) is a very fast-growing Eucalyptus preferring 800 mm or more of rainfall annually and well-drained soils with clay content. It is becoming increasingly popular as a durable plantation species.
Table 1: General characteristics for silvertop
Characteristic | Description |
|---|---|
Botanical name | Eucalyptus sieberi |
Growth rate in preferred conditions | Very fast |
Estimated rotation length (yr) in preferred conditions to produce 60cm diameter at breast height | 20–30 |
Preferred annual rainfall (mm/yr) | 800+ |
Minimum rainfall (mm/yr) | 700 |
Preferred elevation (m) ASL | 0–750 |
Preferred landscape position | Foothills and rises |
Preferred soil | Well-drained soils with clay content |
Prohibitive soil | Soils prone to waterlogging |
Poor drainage tolerance | Low to moderate if on slope |
Dry site tolerance | Moderate |
Frost tolerance | Moderate to high |
Pest and disease problems: trees planted on unsuitable sites are more prone to insect and disease issues | Eucalypt sawflies (Perga spp). Very high susceptibility to Phytophthora cinnamomi. |
Table 2: Timber characteristics for silvertop
Characteristic | Description |
|---|---|
Strength: seasoned timber only | SD3: moderate/high |
Durability: in ground | above ground | 3 | 2 |
Drying: green to 12% moisture content | Care needs to be taken when drying silvertop ash, because of its proneness to surface checking on the tangential surface. It is also slow to dry. Shrinkage about 5.7% radial and 10.6% tangential. |
Main commercial products | Timber framing, flooring, decking, cladding, furniture and high-end joinery. Vehicle construction, handles, fence posts, cases and chemical pulp. |
Bushfire resistance: measured by bushfire attack level (BAL) | BAL 12.5, 19 and 29 – all AS 3959 required applications. Regarded as a bushfire-resistant timber as defined by AS 3837. |
Least attractive features | Drying difficulties, Phytophthora cinnamomi susceptibility. Lack of improved seed options. |
Most attractive features | Fast growth. Tolerance to exposure, durability. A preferred pulp species. |
Status as a plantation species | Becoming increasingly popular. Has found a niche on exposed sites and where fast growth is required. |
Note: Timber characteristics and durability are based on Australian Standard: Timber Natural durability ratings (AS 5604–2005). Refer to the Appendix for an explanatory table. Where (?) applied, rating is based on field experience.
Note: Bushfire resistance measurement is based on naturally bushfire resisting timbers, which are those with inherent bushfire-resisting properties. For more information refer to Australian Standard 3959:2018.
Assumptions and notes
- Sites considered for planting contain at least one metre of soil above an impeding layer (e.g., bedrock or layer impenetrable to roots).
- Please note that most (if not all) eucalypts in Gippsland grow best on sheltered sites.
- Overall slow drying time across air and kiln-dried schedules is recommended to minimise drying degrade. This is the best starting point for inexperienced operators.
References
Beadle CL and Brown AG (eds) 2007. Acacia utilisation and management: adding value. RIRDC Publication No. 07/095, Rural Industries Research and Development Corporation, Canberra.
Boland DJ et. al (1992). Forest trees of Australia. CSIRO Australia.
Bootle KR (1983). Wood in Australia – Types, properties and uses. McGraw Hill, Australia
Carnegie AJ (2002). Field guide to common pests and diseases in eucalypt plantations in NSW. Research and Development Division of State Forests, NSW.
Clarke B, McLeod I and Vercoe T (eds) 2009. Trees for farm forestry: 22 promising species. RIRDC Publication No. 09/015. Rural Industries Research and Development Corporation, Canberra.
Mortimer J (2003). A selection of alternative timbers. Taitua Books, NZ.
National Association of Forest Industries (2004). Timber species and properties, revised edition. Timber Manual Datafile P1
Nicholas ID, Gifford HH and Kimberely MO (1997). Siting black walnut. FRI Bulletin no. 188
Phillips C (1996). Insects, diseases and deficiencies associated with eucalypts in South Australia. Primary Industries SA Forests.
Poole B, Waugh G and Yang JL (2017). Potential for growing and processing durable eucalypts in New Zealand. Publication No. SWP-T036. Solid Wood Innovation. Specialty Wood Products Research Partnership.
Reid R (2017). Heartwood. The art and science of growing trees for conservation and profit. Melbourne Books.
Tepper CJ (2002). Plantation eucalypt species for solid wood products – a profile of Eucalyptus muelleriana. Gottstein Fellowship Report for the Gottstein Memorial Trust
Tepper CJ (2008). Site Matching and Establishing Eucalypt Sawlog Species in Southern Australia. In Beadle CL and Brown AG (eds) 2008. Plantation eucalypts for high value timber. RIRDC Publication No. 08/113, Rural Industries Research and Development Corporation, Canberra.