Natural distribution

Swamp Yate ( Eucalyptus occidentalis ), also known as flat-topped yate, is a small to medium tree native to south Western Australia including the Stirling Ranges. It naturally occurs in open grassy woodlands on alluvial flats that are subject to flooding and have clayey, sometimes saline, soils.

Site preference

Swamp yate has been planted widely for firewood and shelter in temperate regions of the world, including Israel , Italy , Morocco , Chile and Mexico . It is suited to areas with an annual rainfall of 350 – 950 mm. It is usually planted on seasonally wet clay plains and depressions or around freshwater and saline lakes, and sometimes on gravelly sandy loams or granite sands.

Swamp Yate grows well in situations that many trees will not tolerate. It can grow on alkaline, saline and waterlogged sites. It also tolerates dry sites, shallow topsoil and dense clay subsoil, and it is resistant to frost.

Description

Form

Swamp Yate grows to a height of 10 – 20 m with a breast height diameter up to 0.5 m. It has a short trunk below a first fork at 1 – 3 m, with many higher forks forming a moderately dense canopy.

Bark

On most of the trunk and large branches the dark grey to black bark is thick, furrowed, rough and flaky. The smaller branches are contrastingly grey-white and smooth-barked.

Leaves

The bluish-green juvenile leaves are large and oval compared with the glossy green adult leaves, which are long and thin.

Flowers, buds and fruit

Pale yellow flowers appear in April – May. Buds form in groups of 7 and have distinctive horn-shaped caps that can be 3 times as long the base. Fruits are bell-shaped with protruding triangular valves.

Uses

Swamp Yate is grown for wood production, shelter, honey production or amenity, or simply as a hardy tree for difficult sites.

The timber of Swamp Yate is not widely used but its potential as a dense, durable hardwood is being recognized as the species grows in popularity for farm forestry on difficult sites.

Current timber uses:

• construction
• fuel/firewood
• posts and poles

Potential timber uses:

• finer sawn timber products
• pulping

Timber characteristics

The timber has light straw to mid-brown colours and hard, straight-grained heartwood. It has an air-dry density of 850 – 900 kg/m³ and a durability rating of Class 1 (high natural durability with an expected service life of 25 years or more).

Management for sawn timber

Swamp Yate has a moderate growth rate but its form is usually poor unless carefully managed. Good management includes close initial stocking and early form-pruning (age 1 – 2 years). Form pruning should be continued until log height is reached. Rigorous thinning of the trees is needed to ensure the remaining trees will have good enough form to produce sawlogs.

Risks and diseases

Swamp Yate is susceptible to Armillaria root disease. It is also susceptible to attack by sawfly larvae, which may cause defoliation and loss of growth, but trees usually recover.

Seed resources

Improved seed

The Australian Low Rainfall Tree Improvement Group (ALRTIG) is producing improved seed for better tree form and growth, and this is becoming available. Improved seed for low rainfall areas is also available from the PIRSA Bundaleer Seed Production Area (SPA), and seed selected for hardiness on saline sites from the PIRSA Redhill SPA.

Somewhat improved seed can be locally gathered by collecting only from vigorous trees of good form (straight trunk with minimal branching).

Natural provenances

Natural provenances of reasonably good growth and form on a variety of sites include Ongerup, Dumbleyung Lake and Grass Patch. Seed is available through the Australian Tree Seed Centre (ATSC) and WA Forest Products Commission (FPC) Seed Technologies.

Provenances to avoid for timber production include Jerdacuttup, Salt River and Gibson.

Seed collection

Collect between October and February. Capsules will release seed upon drying. Seeds are of similar size to the chaff so the potential for seed cleaning is limited. Yield is about 156 – 256 viable seeds per gram. Alternatively, seed can be purchased from nurseries.

References

Bird, P.R., (2000) Farm Forestry in Southern Australia: a focus on clearwood production of specialty timbers, Victoria , Australia : Department of Natural Resources and Environment.

Boland, D.J., Brooker, M.I.H., Chippendale, G.M., Hall, N., Hyland, B.P.M., Johnston , R.D., Kleinig, D.A., Turner, J.D., (1992) Forest Trees of Australia , Melbourne , Australia : CSIRO Publications.

Keane, P.J., Kile, G.A., Podger, F.D., Brown, B.N., (2000) Diseases and Pathogens of Eucalypts, Melbourne , Australia : CSIRO Publishing.

Acknowledgement

This note was originally written by Lesley Cameron and published in January 2003. It was reviewed by Virginia Forrest in May 2008 and Tim Jackson in May 2009.