Invasive ginger to be eradicated

By CHELSEA JENSEN

Stephens Media

Kahili ginger, a beautiful and fragrant, but prolific ornamental species, has taken root atop Kohala Mountain, slowly destroying the area’s native Hawaiian forest that many rare flora and fauna not only call home, but also require for survival.

Ohia and olapa still provide the forest’s canopy at Puu Pili, however, below the large trees, the forest looks much different than it would have prior to the introduction of nonnative species such as the kahili ginger, Hedychium gardnerianum, said Melora Purell, Kohala Watershed Partnership coordinator.

Native ferns, like hapuu and hoio, mosses and low shrubs like akala, or native Hawaiian raspberry and oha wai, a native flower long thought extinct, once covered the mountain floor, providing not only habitat, but protection from erosion of the area’s soil and watershed, she said.

Today, kahili ginger, some of which is now more than head-high, blankets the mountain, providing little of the protection once supplied by native plants. The invasive plant also blocks sunlight from reaching the ground, inhibiting new native plants from growing.

“The kahili ginger completely displaces everything else in the forest,” Purell said. “In time, the old trees will die and there will be just acres of head-height ginger left.”

According to Purell, there is no place on the 5,480-foot mountain where the ginger has not infiltrated.

“There are places where it’s bad and there are places where we can keep it out by removing it,” she said. “We can’t win the war, but we can win a bunch of battles to get the ginger out.”

The Kohala Mountain Watershed Partnership, with its team of volunteers, interns and “Ginger Ninjas,” is undertaking those battles in an effort to give the native species a chance to re-establishing themselves on Kohala Mountain. Doing so requires hiking the mountain’s muddy slopes and meticulously cutting down the ginger and applying a very mild herbicide, Cimarron, that rots the ginger’s roots, or rhizomes.

“If we tried to dig up all the roots, we’d trash the forest,” Purell explained about why the partnership opts for herbicide. “When the rhizomes rot in place, it seems that the native plants then come in and grow off it.”

The ginger, introduced to Hawaii sometime during the 1920s and 1930s from India, was given the name kahili for its similarity to the Hawaiian feather standards associated with royalty, Purell said. Unlike most forms of ginger, which spread only by rhizome, the kahili ginger also sets seeds that are often carried and dropped by birds, speeding up the species’ spread. It thrives in wet areas like Kohala Mountain’s windward slopes, which receive upward of 160 inches of rain annually.

So far, 12 acres of land at Puu Pili, which is located at about 3,900 feet elevation within the privately owned Kahua Ranch, have been cleared of the ginger. On Tuesday, four applicants for the watershed partnership’s intern program cleared about half an acre of the ginger.

The partnership hopes by the end of the year to remove kahili ginger from nearly 100 acres, Purell said.

The Kohala Watershed Partnership was established in 2003. It was modeled after previous successful watershed partnerships across the state, including one here on Hawaii Island, Purell said. The partnership includes nine private and state landowners. Public lands account for about half of the 70,000 acres included in the agreement.

“That’s 99 percent of the land (on Kohala Mountain) covered,” Purell said.

The partnership’s primary goal, according to its 2007 management plan, is to “show improvements in water and environmental quality … while maintaining the integrity and protecting (the watershed’s) economic, socio-cultural and ecological resources.”

The nonprofit organization operates with a handful of staff on an annual budget of about $800,000 derived from federal and state grants and private contributions, Purell said. This summer the partnership will provide four high school students paid internships, for which it is still raising funds.

Justen Kawamoto, a Waimea resident and soon-to-be senior at Honokaa High School, applied for one of the internship positions because he is an avid hunter who spends a deal of time in Big Island forests. The 17-year-old on Tuesday spent the day slicing down kahili ginger and applying herbicide as part of the application process.

Despite the cold and wet weather, he said he had fun doing the work and believes ridding the land of nonnative ginger will make a difference.

“Being in the forest is relaxing and coming from a hunting experience, it’s good to be able to give back,” he said. “It was a good experience.”

For more information, or to donate to the partnership that is currently working to raise $20,000 for the 2012 summer internship program, visit kohalawatershed.org or email info@kohalawatershed.org.

Email Chelsea Jensen at cjensen@westhawaiitoday.com.