By Alex Kirby BBC News Online environment correspondent

The bongo needs the shelter of bamboo (Image: M Sanbluch/Unep)

The UN Environment Programme says this would threaten habitats and a key food source for humans and wildlife.

Unep says it would also threaten an export trade in bamboo products, estimated to be worth $2.7bn (�1.52bn).

Unep's warning is derived from a novel analysis which combines data on bamboo distribution and existing forest cover.

The report was produced by the International Network for Bamboo and Rattan (Inbar) and Unep's World Conservation Monitoring Centre (Unep-WCMC). It gives no time-scale for the onset of the threat it identifies, saying it will depend on deforestation rates.

Mass die-off

It says the forest destruction threatening woody bamboo (species with a hollow stem supporting the crown) is caused by human pressure.

About 250 of these species have less than 2,000 sq kms of forest (an area the size of the UK capital, London) still within their ranges. The report says many, including relatives of commercially-grown bamboos, have only tiny amounts of forest left.

Unep says the woody bamboos are of more economic and social importance than the grass-like herbaceous species, which are not included in the study.

Although some bamboo species are very fast-growing - one in Japan grows 1.2 metres (almost four feet) a day - their odd life-cycle does not help them.

Bridging the gap: Bamboo proves its worth in Colombia (Image: Jorg Stamm)

In many species all the individuals flower simultaneously, at intervals of a few years to decades, and then die.

Millions of people eat bamboo shoots, and altogether 2.5 billion trade in it or use it. The value of its use for subsistence and in global domestic trade is put at $4.5bn (�2.5bn) annually.

Bamboo is also used for making paper, furniture and instruments, from flutes and drums to the pan pipes of the Andes.

It is sometimes used in combination with modern materials like reinforced concrete or steel for building houses and bridges. The commercial potential of many wild species remains unknown.

Bamboo is an essential part of the diet of many wild creatures, notably the giant panda, which eats nothing else. There are about 600 pandas left in the wild: more than half the bamboo forests where they live have disappeared in the last 30 years.

Other Asian species which depend on bamboo for food or for shelter include the red panda and the world's second smallest bat, the lesser bamboo bat (Tylonycteris pachypus), which is 3.5 cm (1.4 inches) long.

It roosts between the nodes of mature bamboo and enters the stems through holes made by beetles.

Vital refuge

In Africa the endangered eastern mountain gorillas often need bamboo, which in some months forms up to 90% of their diet: fewer than 700 wild gorillas are thought to survive.

Another endangered species, the mountain bongo (Tragelaphus euryceros ssp. isaaci, a large forest antelope) spends the dry season in the dense bamboo thickets of Kenya's Aberdare mountains.

Several lemurs and frogs depend on Madagascar's bamboo forests, which also shelter the ploughshare tortoise or angonoka (Geochelone yniphora).

Spectacled bears and mountain tapirs are among the Latin American creatures which eat large amounts of bamboo.

The lesser bamboo bat could be left homeless (Image: Alex Borissenko)