Our Environment
Crews try to restore Kaho'olawe plant life
By Jan TenBruggencate
Advertiser Columnist
One of the most difficult challenges in reforestation is replanting when the topsoil is gone.
That's the kind of challenge faced on the hardpan of the uplands of Kaho'olawe, and in such places as fields of mine tailings on the Mainland.
Past generations simply abandoned such areas as deserts that were unworthy of the effort of trying to plant them.
Finding ways to make things grow there has turned into as much art as science.
"Hardpan is hard," meaning difficult, said Paul Higashino, restoration manager with the Kaho'olawe Island Reserve Commission.
One issue is that there are few available nutrients in surface area. Another is that water tends to run off or is evaporated by the sun or wind because the area lacks the shade, roots, soil organisms and other things that lock life-giving moisture in the dirt.
Higashino said restoration crews have supplemented some plantings on the hardpan with a product called DriWater, a gel-like compound that lets the roots get water, but keeps it from evaporating.
"We had a higher survival rate with DriWater" than with similar plants that didn't have it, he said. But once the compound was removed, many of those plants died, too.
The restoration crews are experimenting with bales of hay and boxes of wood chips to snag windblown seeds and provide some vegetative material in which roots can get started. They are looking at using compost, rock dust, packets of fertilizer inside the planting holes and other ideas.
A Montana company, Bitterroot Restoration, has made a niche for itself in getting things to grow in similarly difficult terrain.
They have been hired by coal mining companies, the Environmental Protection Agency, the Marine Corps and the National Park Service to restore native ecosystems.
"The propagation of large numbers of hardy native plant species that can survive on the most difficult sites in the world is the heart of (Bitterroot's) success," the company says on its Web site.
Higashino said Bitterroot is one of the leaders in the business, and he hopes to have one of its experts visit Kaho'olawe to provide information next year.
Meanwhile, the Kaho'olawe Island Reserve Commission restoration folks have developed their own list of the hardiest native grasses and shrubs for that island's environment: 'a'ali'i, 'aweoweo, pili, pa'u o Hi'iaka and kawelu. To science, they are Dodonea viscosa, Chenopodium oahuense, Heteropogon contortus, Jacquemontia sandwicensis and Eragrostis variabilis.
Jan TenBruggencate is The Advertiser's Kaua'i bureau chief and its science and environment writer. Contact him at (808) 245-3074 or e-mail jant@honoluluadvertiser.com.
