Excessive soil salinity is a problem that befalls many Australian landscapers, and trying to grow an attractive, healthy stand of trees in particularly saline soils can be a trying endeavour. Large concentrations of salt in your soil can significant damage and stunt unsuitable plant life, as well as provoke changes to soil chemistry that can kill fragile plants and trees. However, living in an area with high soil salinity doesn't mean breaking out the plastic palm trees, as the native Australian ecosystem offers up a range of ornamental trees that are more than hardy enough to deal with salty soils.
Drooping sheoak (Allocasuarina verticillata)
Sheoaks are endemic to Australia, and many sheoak species are well-adapted to growing in highly saline soils. One of the best choices is the drooping sheoak, a small tree with a rounded, drooping crown that provides thick foliage and excellent visual cover. This tree is well suited to planting in salty soils, as its extensive root system and robust cellular structure maximises groundwater absorption while minimising salt damage. As an added bonus, drooping sheoaks harbour colonies of nitrogen-fixing bacteria which add nutrients to poor soils, so a healthy tree can help keep your other plants healthy too.
Red box (Eucalyptus polyanthemos)
Another small native tree, red box is prized for its distinctive green-grey foliage and attractive white blossoms, but also for its tremendous hardiness. Like most other eucalypts, red box is adept at growing well in poor soils, and can deal with high soil salinity, as well as droughts and nutrient-poor soil. They are also very slow growing (although they will grow more quickly if heavily fertilised) making them an excellent choice for urban landscaping where space and low maintenance are at a premium.
Sugar gum (Eucalyptus cladocalyx)
The sugar gum is a large, eye catching tree well suited to larger commercial landscaping projects, where they make excellent windbreaks and sources of shade. The most distinctive aspect of this tree is its bark, which is usually colourfully mottled in shades ranging from grey to brown to bright orange. They also produce attractive, cream-white blossoms in summer. Sugar gums hail from the arid conditions of inland South Australia, and can tolerate very salty soils.
The great advantage of sugar gum trees is that they naturally grow very straight, with branches generally limited to the top half of the tree, resulting in a large tree that can fit in limited growing areas. However, dwarf sugar gums are also available for projects where space is at an absolute premium—these trees have more rounded crowns and crooked trunks, and are suitable for visual screening.