The Tallest Hardwood in the World

The Karri Tree (Eucalyptus Diversicolor) is a native tree unique to the southwest region of Western Australia and belongs to the family Myrtaceae. The name ‘karri’ is the Aboriginal word for the Eucalyptus diversicolour. The tree can grow up to 80m, has smooth pink to silvery-grey bark and a straight trunk with the heartwood of reddish brown. The bark of the karri sheds each year, resulting in a multi-coloured trunk. The leaves are dark green on the upper levels of the tree and gradually became paler on the lower levels. The leaves hang on branches in ‘broccoli’ shaped clusters. The tree produces barrel-shaped fruit. Birds such as the purple crowned lorikeets harvest the pollen and nectar from the white flowers that bloom in the upper areas of the trees by using their brush-like tongues. These birds also assist in pollinating other forest trees. The karri tree grows in belts of rich gravel loam soils and thrives in areas of high winter rainfall. Karri is WA’s tallest tree and one of the tallest hardwood trees in the world. The tree reaches its peak height within a hundred years. The karri belts can be found in the Nannup, Manjimup, Denmark, Margaret River, Albany and Porongurup Range areas of Western Australia’s southwest region.

Karri trees, like jarrah trees, begin their old-growth phase at the ages of 100-150 years and survive to an average of 300 years old. The majority of old-growth karri trees found in Western Australia are less than 200 years old. To sustain these old-growth forests all stages of development must be represented, managed and maintained. Karri forests are best managed by varying rotation ages and varying timber harvesting. The rotation age for karri in Western Australia was set at 100 years but has recently been modified. Fifty percent of all karri forests regenerated after 1990 must be grown to maturity. There are over 55,000 hectares of old-growth karri forests in conservation reserves which are excluded from harvesting

Some of the most famous karri trees in the southwest region are the 60m high Gloucester Tree, the Diamond Tree Lookout and the Bicentennial Tree all located near Pemberton. The Gloucester Tree was used by foresters as a fire watchtower. The Diamond Tree lookout has a cabin built at its peak and was used up until 1974 as a fire lookout.

At William Bay near Denmark, the moving sand dunes are burying living stands of karri forest. The same moving sands are also revealing the upper parts of majestic old karri trees, which were once covered by shifting sand.

Today karri is being marketed worldwide by South African plantation growers. However, plantation supplies are relatively small as some timbers are still considered too immature to cut for timber.

In February 2001, the Western Australian State Government ended logging in all old-growth forests which included the karri forests of the State’s southwest.

Karri has many uses but is generally used for heavy construction but not for dock or harbor structures. Karri is used locally for plywood, furniture and woodchip.