THE Sacha Llanganates mountains in eastern Ecuador are permanently shrouded in fog. They have never been mapped from the ground, or seen from the air. Beneath the mountains鈥� forest canopy live undiscovered species of orchids and other plants. They are typical of one of the planet鈥檚 least explored ecosystems: the cloud forests of the tropics.
These pristine forests are now under threat. The first global survey to map cloud forests in any detail has revealed they cover 380,000 square kilometres 鈥� an area smaller than California 鈥� which is 20 per cent less than previous estimates.
And this figure may itself be an overestimate. For the new maps, generated by compiling satellite images of forest cover, only reveal potential rather than confirmed cloud forests. 鈥淭hey are unseen, up in the clouds and largely neglected in comparison to lowland rainforests,鈥� says Philip Bubb, co-author of the survey report, to be launched at the conference of the UN Convention on Biological Diversity now taking place in Kuala Lumpur, Malaysia.
Advertisement
Bubb and his colleagues from the UNEP World Conservation Monitoring Centre in Cambridge, UK, put together satellite images of forest cover in mountain areas, and determined the altitude ranges within which cloud forests appeared to form in each region.
The researchers then assumed that every forest within each range was a cloud forest. But in fact, some forests in these areas will be drier types 鈥渘ot subject to frequent or seasonal cloud cover鈥�, the report warns, and so 鈥渢he maps may therefore over-represent its occurrence鈥�. Cloud forests are also uniquely vulnerable to climate change. Higher temperatures are already raising the cloud base and drying out the forests, which respond by retreating up the mountainside. What happens when they reach the top, asks Bubb?
The survey also reveals that more than half the world鈥檚 surviving cloud forests are in Indonesia and Papua New Guinea, which are virtually unexplored by biologists.