Emma's Column

posted in: March 2001 | 0

Miconia: The Green Cancer Spreads

You know miconia if you’ve been to Tahiti. This plant, Miconia Calvescens, is also known as “velvet tree” and, to the Tahitians, the “green cancer.” On Tahiti, it thickly covers more than 60 percent of the entire island, and more than 70 percent of its previously diverse forests. Miconia is almost perfectly adapted to destroy: it produces millions of seeds each year, grows quickly in almost any forest habitat, and its very large leaves create dark zones of nothingness on the ground floor, crowding out all light.

    In 1937, a botanical garden shipped miconia from its native Central and South America to the doomed island. In five years it matured, growing around a meter a year, and its thousands of small sweet fruits quickly attracted birds and rats that spread its millions of seeds. These seeds, which can sprout in the hardest, dimmest, most nutrient-poor conditions, grew and took over. The close islands of Mo`orea and Raitea have also become infected from tiny miconia seeds carried on the soles of shoes on travelers from Tahiti.

    Click [url=http://ahi.icsd.hawaii.gov/dlnr/Miconia.html]here[/url] to see a picture of Miconia from the DLNR of Hawai`i.

You know miconia if you’ve been to Hawai`i, too. In 1960, a botanical garden shipped it in to these islands. Miconia was deliberately planted on the islands of Hawai`i and Maui, and like Mo`orea and Raitea, O`ahu and Kaua`i have acquired a few infestations.

Still, the two islands that initially planted miconia have the most colonies by far. It is heavily concentrated east of Hilo on the Big Island, spreading all through northern Puna and west from Hilo along the Hamakua coast. There are also small pockets of miconia along the opposite side of the island in Kona. Maui comes in second, with many different contaminated areas on the highway from Hana (where it was first introduced) to Pa`uwela, and a small sighting in Wailuku. O`ahu and Kaua`i still only have a few known outbreaks: in O`ahu’s Manoa Valley, Kane`ohe and Waimanalo, dispersed along a large area, and in Kaua`i’s Nounou Ridge (Sleeping Giant).

Nelson Ho, who is leading the eradication on the Big Island, explained the process of dealing with infested areas: “The easiest way is to pull up the seedlings, but for larger plants [they can grow higher than 30 feet], a herbicide is used. It is called Ortho Brush B-GON.” The herbicide is sprayed in a 2-5 inch band around the circumference of the trunk, and in a few days the tree is dead.

To tackle an infestation, Ho says, “my dedicated crew of four workers [the Big Island Invasive Species Committee] must find the edge of the miconia area, the very last trees. We must kill those plants and then slowly reduce the area. We really need volunteers, though – we are working in an area the size of O`ahu.”

I asked if total eradication – what we need to completely control miconia – is possible with this level of contamination. “What we are trying to do is kill all of the mature trees, but that will take 5 years minimum,” he said. “And, if funding continues, which is provided from the state Legislature and federal and private grants, miconia might be under control in at the very earliest, 10 years. If funding discontinues, we would be in trouble.”

Will miconia be someday cleared from Maui, also? Maui is in more trouble because of the threat of miconia spreading into Haleakala Park, and the fact that the crew doesn’t know where the infested area ends. Knowing how far the miconia has spread and finding the edges is crucial, which is why they urge people to call their hotline to report sightings.

Will miconia spread in O`ahu and Kaua`i? Oahu is in more danger because miconia is scattered over a large area. A few mature trees were recently discovered on Kaua`i, too, so both islands definitely need volunteers. Even if all the trees are killed on those islands, there still is a threat from seeds that remain viable in the soil for more than 8 years, and reintroduction from seeds carried from other islands.

The fact that the seeds can lie dormant in the soil for so long is the major problem for all islands, but especially for O`ahu and Kaua`i where the all the trees could be killed soon. Because of the seeds, crews will still need to be monitoring areas for at least 8 years, “taking a serious commitment”, says Pat Conant, with the U.S. Department of Agriculture. If seeds sprout later in areas that are no longer monitored, they could mature and create a whole new problem. An example of this is a single tree in O`ahu’s Kalihi Valley that seeded a population that the Sierra Club is still trying to eliminate.

A new problem on O`ahu comes from seeds carried by birds from Manoa Valley, where there is a serious infestation, across the Ko`olau mountains to windward Maunawili. This means that miconia scouts have to explore a huge area with helicopters, which might not see miconia concealed under the tree canopy. Kaua`i has that problem also, but since the area of contamination is relatively small, Conant says, “they have a handle on it, and they have found the edges of the infestation.”

Our islands definitely cannot handle this ruinous introduction, so it is urgent that you become involved by reporting sightings and going on eradication missions. You can write to your state representative of senator at the state Legislature urging them to continue funding the vital “Operation Miconia” (address is printed on the bottom if this page) or go to the Volunteer web link maintained by Environment Hawai`i and find a project on your island.

If you decide to help, you’ll probably be going through forested areas, pulling small trees out and spraying red herbicide bands on the trees, which my Jr. Greenpeace club thought was rather fun. Either way, you’ll be saving a lot of future work eradicating these quickly spreading trees, and saving habitat and species, especially if you live in the Big Island and Maui. We don’t want future generations to see only forests of miconia and to know the pristine native forests of the Hawaiian Islands only from books.

— Emma Yuen

Volunteer Web link:
[url=http://www.environment-hawaii.org/volunteer.htm]http://www.environment-hawaii.org/volunteer.htm[/url]

State Legislature
State Capitol 415 S. Beretania St.
Honolulu, HI 96813

— Emma Yuen

Volume 11, Number 9 March 2001

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