They are immediately recognisable as works by Constable and Van Gogh.

But, on closer inspection there is something missing from these famous paintings: the trees.

An expert in forest mapping has digitally removed the trees from the renowned artworks to highlight the threat of deforestation.

Dr Iain Woodhouse of Edinburgh University's School of Geosciences has cut out the towering elms from Constable's The Haywain and the grey-green foliage from Van Gogh's Olive Trees with Yellow Sky and Sun. He has performed the same trick on the parkland trees in Seurat's Sunday Afternoon on the Island of Grande Jatte.

Dr Woodhouse said: "Trees are a vital global resource, providing fuel, shelter, clean water and food for many species including people, and helping to maintain a healthy atmosphere by harvesting carbon dioxide.

"It is crucial that they do not disappear."

Around 1.4 billion people rely on forests for a major part of their livelihood, Dr Woodhouse says, but an area of woodland the size of a football pitch is destroyed every few seconds.

The altered images are available to view, along with the originals for comparison, at http://forestplanet.wordpress.com.