Invasive Species

Many different types of plants have made it to Hawaii, both by natural and by human initiated processes. These plants often succeed dramatically in the benign environment of the Hawaiian Islands. Typically more aggressive than the competing plants that have lived isolated on the islands for centuries, the invading plants often force the native species out of their habitats. Black Wattle trees are a good example of this process.

Black Wattle (Acacia mearnsii) was introduced to Maui from Australia in the late 1800s. Since then it has spread across most of Haleakala and Kula. In the spring its yellow flower can be seen along the roads and in the fields everywhere in Kula. Because of its rapid growth it is classified as a noxious weed in Hawaii. In Kula it grows in pastures, ravines and is invading the different forested areas. Wattle spreads by copious seed production and basal shoots, growing in tight bunches and creating monotypic thickets. The tree grows 20 to 60 feet tall in 7 years, so it can soon take over any available terrain.

Black Wattle wood from Maui has been tested specifically for use in gasification systems and it makes a suitable fuel. Giving economic value to the wattle trees will allow them to be removed from many areas and mitigation measures to be implemented that will resist the plant's return to those areas. Particularly, wattle needs to be removed from the areas surrounding the various forest reserves. Private land owners are also interested in removing the wattle growth from their properties in order to reclaim pasturelands and to reopen land areas for other uses.