The stumps of 10 rainforest trees, complete with their roots, have been placed around Trafalgar Square to highlight the issue of deforestation.
Laser beams will mark the height the trees would have reached in the wild in comparison to Nelson's Column.
The legally logged trees will highlight deforestation in countries like their native Ghana which has lost 90% of its rainforest in the past 50 years.
Ghost Forest, by Oxford artist Angela Palmer, will remain there until Friday.
The installation went up at the central London location in the early hours of Monday morning.
The trees used in Ghost Forest come from the Suhuma forest reserve in western Ghana.
The artist went to a logging camp to locate trees for the exhibit.
Ms Palmer said: "The concept is to present a series of rainforest tree stumps as a 'ghost forest' - using the negative space created by the missing trunks as a metaphor for climate change, the absence representing the removal of the world's 'lungs' through continued deforestation."
The project has seven indigenous species - Denya, Dahuma, Danta, Hyedua, Mahogany, Wawa and three varieties of Celtis.
The installation, which highlights the threat of deforestation faced by tropical forests, will be shipped to Thorvaldsens Plads in Copenhagen for the start of the UN Climate Change summit in December.
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