HILO, Hawai'i — A forest management plan that proposes to harvest 1.5 million board feet of koa each year from more than 11,000 acres of privately owned conservation land just north of Hilo is being greeted with skepticism by some Big Island residents.

The proposal, by land owner David S. De Luz and Koa Timber Inc., warns that invasive plant species are rapidly infesting the lands above Paka'ikou and Pepe'ekeo, with strawberry guava posing a particular threat to the native koa and 'ohi'a forest.

De Luz and Koa Timber are proposing to launch a control and eradication program for the nonnative species, and to limit the spread of invasive species that are creeping into higher elevations. The land is about 2.5 miles north of Hilo and three miles upslope from Hawai'i Belt Road.

Under the proposal, cut koa logs would be removed from the forest by helicopter to limit the impact on the environment, flown to a staging area, and then trucked from there to Pepe'ekeo Mill of Hilo Harbor for shipping.

Around the stump of each harvested tree, crews would cut down all strawberry guava trees, treat the guava stumps with herbicide, and also poison nonnative grasses.

The crews would take other steps to encourage koa growth, and would then return three more times over the following two years. If koa seedlings are not appearing on their own, the returning crews would plant trees, according to the report.

David Caccia, a Honoka'a sculptor, said he believes the strawberry guava may overwhelm the young koa anyway, and wants the project planners to test out their strategy on a smaller 100-acre parcel and prove it works before they start cutting koa.

"Basically, what they want to do is go in and cut all the koa down and replant it, and we'll have a native forest when they're through, but I don't think that's going to work," he said. Strawberry guava is so tough, dense and fast-growing that "I'm not sure how you get rid of it, and I don't think they know, either," Caccia said.

"It looks like they just want to go in there, rip out the koa and say 'Oh, gee whiz, it's worse than we thought, goodbye.' That's what I see happening," he said.

Micah Miller, who lives across Honoli'i Gulch from the project site, said he agrees with the strategy of managing the forest and removing the invasive species, and has no quarrel with the plan to harvest koa over the next 10 years.

A survey of the property in the 1970s found exotic species covered only about 5 percent of the land, and most of the property was still "pristine native forest." Now, strawberry guava, or wai-awi, has spread to nearly the entire property, and dominates almost 50 percent of the forest from the 1,600-foot to the 2,800- foot elevation, according to the report.

Wild pigs, which eat the guavas and spread the seeds, are also concentrated in the area.

"We've got gorse coming down and waiawi going up," Miller said. (Gorse, also invasive in Hawai'i, is a spiny evergreen shrub from Europe and Africa.) "It's one thing to leave a native forest alone when there's nothing threatening it. That's good, that's true conservation. But when you've got invasives coming in destroying the forest, it takes some husbandry."

However, Miller said, the state does not have the resources to properly police the project to make sure the owner and managers keep their promises.

The state Department of Land and Natural Resources fined Koa Timber $141,000 in 2004 for illegal logging on 13 acres the company owns in the area, and also ordered the company to produce a plan to restore the area.

The company said its crews accidentally strayed off company-owned agricultural lands and into conservation land, where logging cannot be done without a permit.

(Koa wood retails for $10 to $55 a board foot, depending on quality, according to roylam brechtwoodworking.com, Web site of a Kailua, Kona, koa seller. A board foot is 12 inches square and one inch thick.)

Miller said he and his neighbors had to press the DLNR to pursue that case because state officials said they did not have the staff to investigate the violation. "The DLNR doesn't have the facilities or the manpower to check on those guys. That's my main complaint," he said.

Similar proposals to harvest koa on the property have repeatedly stalled. Koa Timber first announced its plan for harvesting on conservation land in 2000, but withdrew its application for a state permit to prepare an environmental impact statement.

The company submitted the EIS in 2003, but withdrew it the next year to make changes. Then, state officials declared in 2005 that a new EIS was required, and the company withdrew its conservation district use permit application.

Reach Kevin Dayton at kdayton@honoluluadvertiser.com.