Easter Island is an island in the southeastern Pacific Ocean, at the southeasternmost point of the Polynesian Triangle in Oceania.
Easter Island, together with its closest neighbour, the tiny island of Isla Salas y Gómez 415 km farther east, is recognized by ecologists as a distinct ecoregion, the Rapa Nui subtropical broadleaf forests. The original subtropical moist broadleaf forests are now gone, but paleobotanical studies of fossil pollen, tree moulds left by lava flows, and root casts found in local soils indicate that the island was formerly forested, with a range of trees, shrubs, ferns, and grasses. A large extinct palm, Paschalococos disperta, related to the Chilean wine palm, was one of the dominant trees as attested by fossil evidence. Like its Chilean counterpart it probably took close to 100 years to reach adult height. The Polynesian rat, which the original settlers brought with them, played a very important role in the disappearance of the Rapa Nui palm. Although some may believe that rats played a major role in the degradation of the forest, less than 10% of palm nuts show teeth marks from rats. The remains of palm stumps in different places indicate that humans caused the trees to fall because in large areas, the stumps were cut efficiently. In 2018, a New York Times article announced that Easter Island is eroding.
The clearance of the palms to make the settlements led to their extinction almost 350 years ago. The toromiro tree was prehistorically present on Easter Island, but is now extinct in the wild. However, the Royal Botanic Gardens, Kew and the Göteborg Botanical Garden are jointly leading a scientific program to reintroduce the toromiro to Easter Island. With the palm and the toromiro virtually gone, there was considerably less rainfall as a result of less condensation. After the island was used to feed thousands of sheep for almost a century, by the mid-1900s the island was mostly covered in grassland with nga'atu or bulrush in the crater lakes of Rano Raraku and Rano Kau. The presence of these reeds, which are called totora in the Andes, was used to support the argument of a South American origin of the statue builders, but pollen analysis of lake sediments shows these reeds have grown on the island for over 30,000 years. Before the arrival of humans, Easter Island had vast seabird colonies containing probably over 30 resident species, perhaps the world's richest. Such colonies are no longer found on the main island. Fossil evidence indicates six species of land birds, all of which have become extinct. Five introduced species of land bird are known to have breeding populations,
Lack of studies results in poor understanding of the oceanic fauna of Easter Island and waters in its vicinity; however, possibilities of undiscovered breeding grounds for humpback, southern blue and pygmy blue whales including Easter Island and Isla Salas y Gómez have been considered. Potential breeding areas for fin whales have been detected off northeast of the island as well.
Vegetation on the islandSatellite view of Easter Island 2019. The Poike peninsula is on the right.Digital recreation of its ancient landscape, with tropical forest and palm treesHanga Roa seen from Terevaka, the highest point of the islandView of Rano Kau and Pacific Ocean
Satellite view of Easter Island 2019. The Poike peninsula is on the right.
Digital recreation of its ancient landscape, with tropical forest and palm trees
Hanga Roa seen from Terevaka, the highest point of the island
View of Rano Kau and Pacific Ocean
The immunosuppressant drug sirolimus was first discovered in the bacterium Streptomyces hygroscopicus in a soil sample from Easter Island. The drug is also known as rapamycin, after Rapa Nui. It is now being studied for extending longevity in mice.
Trees are sparse, rarely forming natural groves, and it has been argued whether native Easter Islanders deforested the island in the process of erecting their statues, and in providing sustenance for an overconsumption of natural resources from a overcrowded island.
Given the island's southern latitude, the climatic effects of the Little Ice Age may have exacerbated deforestation, although this remains speculative. Many researchers point to the climatic downtrend caused by the Little Ice Age as a contributing factor to resource stress and to the palm tree's disappearance. Experts, however, do not agree on when the island's palms became extinct.
Jared Diamond dismisses past climate change as a dominant cause of the island's deforestation in his book Collapse which assesses the collapse of the ancient Easter Islanders. Influenced by Heyerdahl's romantic interpretation of Easter's history, Diamond insists that the disappearance of the island's trees seems to coincide with a decline of its civilization around the 17th and 18th centuries. He notes that they stopped making statues at that time and started destroying the ahu. But the link is weakened because the Bird Man cult continued to thrive and survived the great impact caused by the arrival of explorers, whalers, sandalwood traders, and slave raiders.
Midden contents show that the main source of protein was tuna and dolphin. With the loss of the trees, there was a sudden drop in the quantities of fish bones found in middens as the islanders lost the means to construct fishing vessels, coinciding with a large increase in bird bones. This was followed by a decrease in the number of bird bones as birds lost their nesting sites or became extinct. A new style of art from this period shows people with exposed ribs and distended bellies, indicative of malnutrition, and it is around this time that many islanders moved to live in fortified caves, and the first signs of warfare and cannibalism appear.
Soil erosion because of lack of trees is apparent in some places. Sediment samples document that up to half of the native plants had become extinct and that the vegetation of the island drastically altered. Polynesians were primarily farmers, not fishermen, and their diet consisted mainly of cultivated staples such as taro root, sweet potato, yams, cassava, and bananas. With no trees to protect them, sea spray led to crop failures exacerbated by a sudden reduction in freshwater flows. There is evidence that the islanders took to planting crops in caves beneath collapsed ceilings and covered the soil with rocks to reduce evaporation. Cannibalism occurred on many Polynesian islands, sometimes in times of plenty as well as famine. Its presence on Easter Island is supported by oral histories.
Benny Peiser noted evidence of self-sufficiency when Europeans first arrived. The island still had smaller trees, mainly toromiro, which became extinct in the wild in the 20th century probably because of slow growth and changes in the island's ecosystem. Cornelis Bouman, Jakob Roggeveen's captain, stated in his logbook, '... of yams, bananas and small coconut palms we saw little and no other trees or crops.' According to Carl Friedrich Behrens, Roggeveen's officer, 'The natives presented palm branches as peace offerings.' According to ethnographer Alfred Mètraux, the most common type of house was called 'hare paenga' because the roof resembled an overturned boat. The foundations of the houses were made of buried basalt slabs with holes for wooden beams to connect with each other throughout the width of the house. These were then covered with a layer of totora reed, followed by a layer of woven sugarcane leaves, and lastly a layer of woven grass.
Peiser claims that these reports indicate that large trees existed at that time, which is perhaps contradicted by the Bouman quote above. Plantations were often located farther inland, next to foothills, inside open-ceiling lava tubes, and in other places protected from the strong salt winds and salt spray affecting areas closer to the coast. It is possible many of the Europeans did not venture inland. The statue quarry, only one kilometre from the coast with an impressive cliff 100 m high, was not explored by Europeans until well into the 19th century.
Easter Island has suffered from heavy soil erosion in recent centuries, perhaps aggravated by agriculture and massive deforestation. This process seems to have been gradual and may have been aggravated by sheep farming throughout most of the 20th century. Jakob Roggeveen reported that Easter Island was exceptionally fertile. 'Fowls are the only animals they keep. They cultivate bananas, sugar cane, and above all sweet potatoes.'