From the National Tropical Botanical Garden Digging into the past to find the future Palaeo-ecology meets restoration biology
On both the north and south shores of odds posed by aggressive alien plants and DAVID A. BURNEY Kauai, NTBG has several exciting new animals has been that NTBG staff pay DIRECTOR OF CONSERVATION, restoration projects with ties to palaeo- close attention to ecological history in NATIONAL TROPICAL ecology and archaeobotany. These planning its restorative efforts. Hawaiian BOTANICAL GARDEN include a project along the coast fronting oral traditions, early historical accounts, the Allerton Garden, an area called Lawai and particularly information from archae- cological restoration projects in Kai, which was initiated by grants from ological and palaeo-ecological sites near the Hawaiian lowlands have little the US Fish & Wildlife Service and the the restorations have provided useful Eto go on in terms of intact Natural Resources Conservation Service evidence concerning the site’s potential coastal forest ecosystems to serve as (USDA). In the more inland parts of the for restoration, serving as reference models. Nevertheless, a program of Lawai Valley, NTBG’s McBryde Garden systems or restoration targets for various palaeo-ecological research has led to some has new restoration projects underway projects. unique restoration initiatives by the aimed at protecting rare plant species National Tropical Botanical Garden on adapted to dry upland conditions on the At Makauwahi Cave on Kauai’s spectacu- Kauai. For instance, palaeo-botanical island’s leeward slopes. Initial funding of lar Mahaulepu coast, our research group evidence from a cave site a few miles the project in McBryde was made possi- has excavated more than 200 m3 of sedi- from NTBG’s southshore gardens has ble through NTBG Fellows, a major ment from a sinkhole palaeolake in the given scientists their most detailed support group of the organization. centre of the cave system, yielding a evidence yet for how coastal vegetation NTBG’s Limahuli Garden on the north 10,000-year record of changes in sea level, before humans would have looked. As it shore has restored traditional Polynesian environmental conditions and biota. The turns out, the list of species in coastal dry pondfields and other dramatic landscapes fossil-rich mud of this site has yielded forests was quite long and included many through careful attention to the details of about 45 species of fossil birds, for endangered taxa that are represented in local oral traditions and data from adja- instance, as well as more than a dozen the wild today only by a few individuals cent archaeological sites. types of extinct land snails, and a rich at remote inland sites, or that are extinct record of early Polynesian diet and life- on the island but have survived on a A key link in the process of finding the ways. Most germane to the question of neighbouring island. successful path to restoration against the what types of vegetation grew there in the past and could be targets for future restorations, of course, were abundant well-preserved fossil spores and pollen, seeds and fruits, and even leaves, twigs and whole tree trunks.
This material showed that, for thousands of years before human arrival, the site was surrounded by a woodland dominated by a small-fruited native loulu palm (Pritchardia cf. aylmer-robinsonii) and a wide array of trees and shrubs. This remarkable vegetation included plenty of kou (Cordia subcordata), a species formerly believed by most botanists to have been brought to the islands by Polynesians. Our radiocarbon dating shows clearly that this tree, as well as hala (Pandanus tectorius), were part of the indigenous flora.