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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

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Tree Removal Suffolk County
May 30, 2012

Wow, its hard to believe that the life of another tree can so greatly and dangerously harm its entire ecosystem. But if it is that big of a deal, its obvious that they must go from Samoa. The question is; how do you go about performing a safe, and efficient massive removal?


May 21, 2013

If the USDA recognizes non-native or invasive tree species to be a problem, how does it feel about the potential for genetically modified tree species to effect forest ecology and stability in North America?

Tree Top
Feb 24, 2016

As much as we love to encourage more tree growth, it is also alarming to learn more about invasive trees. Their effects on the entire ecosystem is a call out for immediate action. Happy to know the efforts from USDA. On a small scale effort, it would be great if individual tree owners concentrate on keeping invasive plant species at bay in their own yard.

Competition Tree
May 25, 2016

It's always worrisome to hear about "invasive" trees, but if it's really a problem can't something be done to remove the trees?

Jun 01, 2016

This is useless for my school project