short answer: because they cut all the trees… so basically a over use of resources.

another statue

long answer:

When the first Europeans visited the island in the eighteenth century it was completely treeless apart from a handful of isolated specimens at the bottom of the deepest extinct volcano crater of Rano Kao. However, recent scientific work, involving the analysis of pollen types, has shown that at the time of the initial settlement Easter Island had a dense vegetation cover including extensive woods. As the population slowly increased, trees would have been cut down to provide clearings for agriculture, fuel for heating and cooking, construction material for household goods, pole and thatch houses and canoes for fishing. The most demanding requirement of all was the need to move the large number of enormously heavy statues to ceremonial sites around the island. The only way this could have been done was by large numbers of people guiding and sliding them along a form of flexible tracking made up of tree trunks spread on the ground between the quarry and the ahu. Prodigious quantities of timber would have been required and in increasing amounts as the competition between the clans to erect statues grew: As a result by 1600 the island was almost completely deforested and statue erection was brought to a halt leaving many stranded at the quarry.

The team working on the dig as they unveil the secrets of the heads - excavations recently exposed the torsos of two 7m tall statues

The team working on the dig as they unveil the secrets of the heads – excavations recently exposed the torsos of two 7m tall statues
Read more: http://www.dailymail.co.uk/sciencetech/article-2149846/Hidden-treat-The-Easter-Island-heads-BODIES.html#ixzz2SRnODvrh
Follow us: @MailOnline on Twitter | DailyMail on Facebook

The deforestation of the island was not only the death knell for the elaborate social and ceremonial life it also had other drastic effects on every day life for the population generally. From 1500 the shortage of trees was forcing many people to abandon building houses from timber and live in caves, and when the wood eventually ran out altogether about a century later everyone had to use the only materials left. They resorted to stone shelters dug into the hillsides or flimsy reed huts cut from the vegetation that grew round the edges of the crater lakes. Canoes could no longer be built and only reed boats incapable of long voyages could be made. Fishing was also more difficult because nets had previously been made from the paper mulberry tree (which could also be made into cloth) and that was no longer available. Removal of the tree cover also badly affected the soil of the island, which would have already suffered from a lack of suitable animal manure to replace nutrients taken up by the crops. Increased exposure caused soil erosion and the leaching out of essential nutrients. As a result crop yields declined. The only source of food on the island unaffected by these problems was the chickens. As they became ever more important, they had to be protected from theft and the introduction of stone-built defensive chicken houses can be dated to this phase of the island’s history. It became impossible to support 7,000 people on this diminish ing resource base and numbers fell rapidly

After 1600 Easter Island society went into decline and regressed to ever more primitive conditions. Without trees, and so without canoes, the islanders were trapped in their remote home, unable to escape the consequences of their self-inflicted, environmental collapse. The social and cultural impact of deforestation was equally important. The inability to erect any more statues must have had a devastating effect on the belief systems and social organisation and called into question the foundations on which that complex society had been built. There were increasing conflicts over diminishing resources resulting in a state of almost permanent warfare. Slavery became common and as the amount of protein available fell the population turned to cannibalism. One of the main aims of warfare was to destroy the ahu of opposing clans. A few survived as burial places but most were abandoned. The magnificent stone statues, too massive to destroy, were pulled down. The first Europeans found only a few still standing when they arrived in the eighteenth century and all had been toppled by the 1830s. When they were asked by the visitors how the statues had been moved from the quarry, the primitive islanders could no longer remember what their ancestors had achieved and could only say that the huge figures had `walked‘ across the island. The Europeans, seeing a treeless landscape, could think of no logical explanation either and were equally mystified.

more statues
©Cliff Wassmann

sources: http://www.eco-action.org/dt/eisland.html

what is fascinating about history?

that all the problems we face today… have allready been there, but sometimes forgotten.

Few historical tales of ecological collapse have achieved the cultural resonance of that of Easter Island. In the conventional account, best popularised by Jared Diamond in his 2005 book ‘Collapse’, the islanders brought doom upon themselves by over-exploiting their limited environment, thereby providing a compelling analogy for modern times. Yet recent archaeological work suggests that the eco-collapse hypothesis is almost certainly wrong – and that the truth is far more shocking.

another question: how many of us, will die out, if we ran out of oil?

did you know why indians did not know the concept of „private property“? because nature was a ABUNDANT resource to their lifestyles.

did you know why the dutch settled @ Manhattan, nowadays main island of New York City? Because it was ABUNDANT with natural resources, before it was all covered with concrete.