Easter Island Environment

Environment of Easter Island

Rapa Nui is a barren island, but this was not always the case. Studies of pollen cores prove that the first Polynesian settlers found an island paradise of lush, subtropical forest6. Within 400 years of colonization, deforestation was well underway5.

700 years after colonization, the forests were gone, every species of land bird was extinct and shellfish were overexploited. Without trees, the inhabitants could no longer make sea faring canoes with which to hunt porpoises, the main staple of their diet.

Without the population lacking sea faring ability, Rapa Nui became a closed system. The inhabitants could not abandon the island and turned to intensive poultry production; rats also became a dietary staple.

Without wood to burn for cooking and heating fires, sugarcane scraps, grass and sedges were used instead, which in turn impoverished the soil. The population crash happened about 200 years later. In 1722, Jacob Roggeveen found barren grassland, a landscape devoid of trees and shrubs. Botanists have since identified only 47 species of plants, two shrubs and two tree types. In recent years, the accidental introduction of the thistle to the island could become a serious problem.

One of the tree types, the toromiro, used to grow in great numbers on Rapa Nui. It is a small leguminous tree with yellow flowers. Its beautiful and resistant wood was used for making, among other things, the famous moai 'kava kava'. Palm trees have been planted over the last 30 years and Easter Island is no longer the barren, treeless island that many texts lead you to believe.

At the time Thor Heyerdahl visited Rapa Nui in 1956, there was apparently but one, very sick, toromiro left. Found by Thor at the base of the Rano Koa crater, he removed a single living branch bearing seed-filled pods and had it delivered to Professor Selling, who in turn took them to the Botanical Garden of Gotebourg.

By 1980, there were two toromiro plants alive in Gotebourg and it was decided to attempt to reintroduce the plant to Rapa Nui. This and a second attempt in 1988 resulted in failure, due to a root nematode that killed all the seedlings.

As of 1995 there are still no well-established toromiros on Rapa Nui and all the samples originate from just one tree. However, all is not lost, in 1994 four European botanic gardens, including the Royal Botanic Gardens in Kew, set up a special Toromiro Management Group to co-operate in the reintroduction project and the enlarging of the dangerously low gene pool of Rapa Nui toromiro.

More on Sophora toromiro

Sophora toromiro once formed part of the natural vegetation of Easter Island. It is now extinct in the wild. A prolonged history of habitat destruction has resulted in the loss of the island's original scrub and forest. The first European navigators noted the Toromiro, recording areas as "covered with a shrubbery of the mimosa ... to the height of 8 or 9 feet." However following the introduction of domestic livestock, those surviving clumps were rapidly destroyed by browsing. The last surviving tree was recorded by Scottsberg in 1917 within the crater Rano Kau. This tree survived until 1962. The only plants that can be confirmed as genuine S. toromiro are descendants from this single founder and survive in cultivation within European and Australian botanic gardens, the National Botanic Garden in Viña del Mar, Chile and private gardens in Chile.

Reference: Toromiro Management Group
Reference: Conservation of the Toromiro Tree: Case Study in the Management of a Plant Extinct in the Wild

Trees, in general, are beginning to return to the landscape. Rana Kao is now covered with trees and Rano Raraku has trees at its base. Although there is a long way to go, you could not say that Easter Island is tree-less. There are other plants that are new introductions which are beginning to find the climate nurturing. The thistle, common in Scotland, is now becoming a nuisance on the island, unfortunately there appears to be little awareness of the severity of an island full of thistles.