Cloud forests

Posted: 7 May 2008

Cloud forests - a type of rainforest - occur on high mountains in the tropics, generally between 2,000 and 3,500 metres, and experience very different environmental conditions. As one ascends in elevation, the hot steamy lowlands are left behind and several distinct vegetation zones occur, including lower montane forest, cloud forest or upper montane forest, and even an alpine zone if the mountain is high enough.

Cloud forest, Mexico. Photo P. Bubb
Cloud forest, Mexico. Photo P. Bubb
Cloud forest, Mexico. Cloud forest is a rare type of forest, making up only 2.5% of the total areas of the world's tropical forests© P. Bubb

The height of the trees is much lower, and in fact, the trees usually appear crooked and stunted, due to exposure to wind, sun, and cold. Cloud forests are so named because they are often shrouded in mist and fog. The high moisture level and cool year-round temperatures foster plant communities rich in mosses, ferns, and epiphytes, a habitat that scientists are beginning to study and catalog with increasing interest.

Vital resource

The Earth’s cloud forests are vital and unique habitats for thousands of rare and endangered species and suppliers of year-round water supplies for farmers, rural communities and many rapidly growing cities, are under increasing threat from factors including agriculture, road-building and climate change.

The first comprehensive survey of these rare, romantic and fragile worlds, indicate that cloud forests are rarer than thought, with the true area 20% less than the previous estimate of half a million square kilometres. New figures show that cloud forests cover an area of just under 400,000 square kilometres, or less than 2.5 per cent of the globe’s tropical rain forests.

One surprising finding is that, contrary to previous estimates, the majority of these moist humid forests are found in Asia rather than Latin America.

Indeed, the report, Cloud Forest Agenda, estimates that 60 per cent of cloud forests are found in Asia with around 25 per cent in Latin America and 15 per cent in Africa.

Area of potential cloud forest and tropical mountain forest by continental region. UNEP-WCMC
Area of potential cloud forest and tropical mountain forest by continental region. UNEP-WCMC
Figure 1 - Area of potential cloud forest and tropical mountain forest by continental region© UNEP-WCMC

The findings underline the vital need for improved monitoring and conservation measures in Asia, including regeneration of damaged and degraded cloud forests. Priority countries may include Indonesia and Papua New Guinea which have been found to hold considerable amounts of cloud forest.

The report makes it clear that conserving and restoring cloud forests is not a only a matter of aesthetics or a love of nature, but one of crucial economic importance for millions of people in the developing world.

Water supplies

The ability of cloud forests to strip and retain moisture from cloud and fogs is key to abundant, clean and predictable water supplies in many areas, especially during dry seasons. The cloud forests of La Tigra National Park in Honduras provide over 40 per cent of the water for the 850,000 people living in the capital, Tegucigalpa.

Other cities where cloud forests supply significant amounts of water include Quito, Ecuador, Mexico City and Dar Es Salaam. All the water used by the Tanzanian capital in the dry season for drinking and powering hydroelectricity originates in the cloud forests of the Uluguru Mountains.

The forests of Mount Kenya guarantee the dry-season river flows to the semi-arid lowlands with the headwaters of the River Tana supplying water to over five million people. River systems in the Mount Kenya area also supply other urban centres, Kenya’s blossoming international exports of flowers, as well as wildlife and tourist centres.

Climate Change

A unique feature of these forests is that they can capture moisture through condensation from the clouds, which also makes these habitats very sensitive to climate change. If temperatures rise one degree in the lowland this equates to two degrees in the mountain and can result in the clouds lifting and the cloud forest drying out.

Biodiversity

The unique conditions found in cloud forests make them ideal breeding grounds for special species often found nowhere else in the world. Species found there include the endangered spectacled bear, the mountain gorillas of Africa and the Resplendent Quetzal, a colorful bird which is the national symbol of Guatemala.

The huge concentration of unique, endemic species is underscored by the Andean cloud forests. In Peru, over 30 per cent of the 272 species of endemic mammals, birds and frogs are found in cloud forests.

Aethantus mutissi flower, Columbia. A cloud forest laurel tree which is pollinated by the sword-billed hummingbird. Photo W. Ferwerda
Aethantus mutissi flower, Columbia. A cloud forest laurel tree which is pollinated by the sword-billed hummingbird. Photo W. Ferwerda
Aethantus mutissi flower, Columbia. A cloud forest laurel tree which is pollinated by the sword-billed hummingbird© W. Ferwerda
Even tiny pockets of cloud forest can harbour an extraordinary variety of life forms. For example, the Centinella Ridge in Western Ecuador has about 90 endemic plant species in a forest area of just 20 square kilometres.

New species are often being discovered in cloud forests. In the 1990s the Jocotoco Antipitta, a bird, was found in about 5,000 hectares of Ecuadorian cloud forest, as was the Scarlet-banded Barbet. It was discovered in cloud forest near the headwaters of the Rio Cushabatay, Peru.

A new genus of the cow family and two new species of barking deer were discovered in the Annamite cloud forests of Laos and Vietnam as recently as 1996.

Crop improvements

Cloud forests are the natural habitats of the wild relatives of important crops and therefore important gene pools for crop improvements.

Recent studies have found wild living relatives of papaya, the tomato, tree tomato, passion fruit, avocado, beans, blackberry, cucumber, potato and peppers in cloud forests.

Threatened forests

The report identifies nearly a dozen major threats to cloud forests including clearance for farming and grazing land and habitat fragmentation.

In Africa, 10 out of 15 countries questioned said poaching and hunting of animals such as great apes was a key threat. Fires were also highlighted as a key problem in African countries.

Seven out of ten Asian countries, including Indonesia, Malaysia and the Philippines, mentioned timber extraction and logging as an issue, with seven African and four Asian nations citing collection for fuelwood and charcoal production as a possible threat.

Road construction was cited as a threat in six Latin American countries. Studies in Puerto Rico indicate that cloud forest soils can take up to 300 years to recover from such construction. Road and tourists developments, including golf courses, are threatening forests in Southeast Asia, in Malaysia’s Genting and Cameron Highlands and Sabah’s Mount Kinabalu.

Cloud forest cleared for pasture, Columbia. Photo W. Ferwerda
Cloud forest cleared for pasture, Columbia. Photo W. Ferwerda
Cloud forest cleared for pasture, Columbia. Extensive cattle-ranching has continued to expand, at the cost of both Andean forests and arable agriculture© W. Ferwerda

Clearance of cloud forests for either illegal opium or coca leaf is reported in Colombia, Bolivia, Peru and Venezuela. Indeed, loss of habitat has been a particular problem for the spectacled bear in the Andes. Deforestation has affected migration routes and there have been conflicts with farmers where bears have been eating new crops. Wildlife corridors in cloud forests are essential if man and bear are to co-exist.

Introduction of alien species can also be an issue. Cloud forests in Jamaica are threatened by an introduced Australian tree, and feral pigs in Hawaiian cloud forests have led to plant and bird extinctions.

Conservation opportunities

Eco tourists, Monteverde, Costa Rica.  Photo: P. Bubb
Eco tourists, Monteverde, Costa Rica. Photo: P. Bubb
Eco tourists, Monteverde, Costa Rica. People are attracted by the beauty of the cloud forests, the mountain environment and the rare birds. © P. Bubb

Some countries are now implementing innovative schemes to save cloud forests. Costa Rica, for example, under its 1996 Forest Law, pays landowners who conserve or re-establish forests. Hydro-electric companies also pay up to US$40 a hectare a year to landowners with cloud forests in recognition of their role in maintaining water supplies.

Cloud forest tourism can also be a valuable source of income for local people and thus a reason to conserve these habitats. The report cites schemes in Africa, including trips to see the mountain gorillas in the cloud forests of the Democratic Republic of the Congo, and others schemes in Asia and Latin America.

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