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Removal of Invasive Tree Improves Health of American Samoa Forests

Posted by Sherri Eng, Public Affairs Specialist, U.S. Forest Service Pacific Southwest Research Station in Forestry
Apr 27, 2012
Dead Tamaligi trees with recovering native forest in the National Park of American Samoa. Photo credit: Tavita Togia, National Park of American Samoa.

Removal of destructive invasive trees is an ongoing challenge for the U.S. Forest Service. What folks might not realize is that this challenge of protecting native forests extends all the way to the South Pacific. 

Since 2001, there has been an aggressive field campaign to eliminate the Tamaligi tree within the boundaries of the National Park of American Samoa. Samoa’s forests are important to the Pacific Ocean’s Polynesia/Micronesia biodiversity. These islands support some of the most intact native ecosystems of any Pacific Island group.

According to a recent study about the Tamaligi tree -- an invasive and destructive tree found on Tutuila Island, American Samoa -- the eradication of the tree greatly improves the health of the island’s diverse native forests.

A team of scientists from the U.S. Forest Service and the National Park of American Samoa investigated how Tamaligi trees affected the composition, biomass and soil nitrogen in forests within or adjacent to island’s national park. The team sampled forests with Tamaligi, and also forests where Tamaligi had been present, but subsequently removed.

Findings from the study demonstrated the strong influence of Tamaligi on the functioning of American Samoa native forests. The Tamaligi-invaded forests show that this invasion replaces, rather than augments native trees in these forests. However, once Tamaligi trees are controlled, the native trees quickly recover and shade out any future Tamaligi regeneration.

“The effort to eliminate Tamaligi populations from the National Park of American Samoa is a great and inspiring example of successful control of an invasive species,” said Dr. R. Flint Hughes, a U.S. Forest Service scientist who led the study.

Category/Topic: Forestry