An alliance of European local authorities, national governments, US film stars, Japanese shops, soft drink companies and Russian foundations have stepped in to prevent oil companies exploiting 900m barrels of crude oil from one of the world's most biologically rich tracts of land.

According to the UN, the "crowdfunding" initiative had last night raised $116m (£75m), enough to temporarily halt the exploitation of the 722 square miles of "core" Amazonian rainforest known as Yasuní national park in Ecuador.

The park, which is home to two tribes of uncontacted Indians, is thought to have more mammal, bird, amphibian and plant species than any other spot on earth. Development of the oilfield, which was planned to take place immediately if the money had not been raised, would have inevitably led to ecological devastation and the eventual release of over 400m tonnes of CO2.

Ecuador agreed to halt plans to mine the oilfield if it could raise 50% of the $7.6bn revenue being lost by not mining the oil. While the world's leading conservation groups pledged nothing, regional governments in France and Belgium offered millions of dollars – with $2m alone from the Belgian region of Wallonia. A New York investment banker donated her annual salary and Bo Derek, Leonardo DiCaprio, Edward Norton and Al Gore all contributed.

The idea of asking people to pay for something not to take place was widely dismissed by national treasuries as holding the world to ransom. The German development minister, Dirk Niebel, said that the principle of paying for the oil not to be exploited "would be setting a precedent with unforeseeable referrals".

However, Germany has now contributed $48m in "technical assistance". The former Italian prime minister Silvio Berlusconi was widely criticised after he wrote off $51m of Ecuador's $10bn external debt as Italy's contribution.

Other governments pledging support were Chile, Colombia, Georgia and Turkey ($100,000 each), Peru ($300,000), Australia ($500,000) and Spain ($1.4m).

Supporters of the scheme argued that it could be a model for change in the way the world pays to protect important places. The money raised is guaranteed to be used only for nature protection and renewable energy projects. Nigeria, Cameroon, Gabon and other countries with oil reserves, have investigated the possibility of setting up similar schemes as an alternative to traditional aid.

The biological richness of Yasuní has astonished scientists. One 6sq km patch of the park was found to have 47 amphibian and reptile species, 550 bird, 200 mammal and more species of bats and insects than anywhere in the western hemisphere. According to Ecuadorean scientists, it would take in the region of 400 years to record Yasuní's 100,000 or more insect and 2,000 fish species.

Of the 63.4% of Ecuadoreans polled last month who knew of the Yasuní initiative, 83.4% supported it.

(By John Vidal, Guardian.co.uk, 30/12/2011)