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Cloud Forests Fading in the Mist, Their Treasures Little Known

They are nature's "water towers," providing billions of gallons of fresh, clean, filtered water. They are home to thousands of indigenous peoples, and storehouses of biodiversity, at least 80 percent of which has not yet been catalogued.

Research biologist

Mario Percy Nuñez Vargas, a research biologist in Cuzco, Peru estimates cloud forests are disappearing at such a rate that they will be gone within ten years. He is pictured with Masdevallia veitchiana, an orchid species endemic to the Andes cloud forest.
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Photograph by David Braun/NGS


Yet in as little as ten years' time, biologists warn, the world's cloud forests—evergreen mountain forests that are almost permanently shrouded in mist and clouds—may be all but gone.

They are being cleared for cattle grazing and coca plantations. Logged to provide fuel for heating and cooking. Paved over and developed to make way for transportation and telecommunications networks. They are being damaged and dried out by air pollutants and global warming.

Now, cloud forests are rising to the top of the world's scientific and conservation agenda. But will scientists learn enough about these important ecosystems to be able to convince the world to conserve them before they are gone forever?

Percy Nuñez, a research biologist in Cuzco, Peru, who studies cloud forests, estimates they are disappearing at a such a rate that the "the cloud forest will all be gone in the next ten years."

"We don't know about our resources—80 to 90 percent of the cloud forests are a mystery to us all," Nuñez said.

Yet scientists have barely begun assessing the wide range of species that clod forests harbor, he noted. "We don't have biologists working in cloud forests. We are not training young scientists to do the work," he said.

Now, he added, "we are working with NASA, using satellite images to get some idea of what's there before it is gone. There aren't any field guides available."

Essential Irrigation

Cloud forests are broadly defined as forests that are frequently covered in clouds or mist. They are found in tropical and subtropical mountainous regions of the world, where cooler temperatures on mountain slopes cause clouds to form.

In Central and South America, cloud forest stretches from Panama to northern Argentina. "It's the belt between the jungle and the highlands and, as such, is narrow and delicate. It is also known as the 'eyebrow of the jungle,' " Nuñez explained.

On continental landscapes, cloud forests are found at 5,000 to 10,000 feet (1,500 and 3,000 meters) above sea level. They often occur at much lower heights—as low as 1,600 feet (500 meters)—on oceanic islands, such as in the Caribbean and Hawaii. The trees in cloud forests are generally 50 to 65 feet tall (15.2 to 18.3 meters) at lower elevations, much shorter and mossier at higher elevations.

The trees perform a crucial hydrological function. They strip water from windblown fog and clouds, aiding the healthy functioning of surrounding ecosystems.

"One of the key things is they are important for capturing water from clouds, which provides water downstream to industry, towns, and regions," said Phillip Bubb, director of the Tropical Montane Cloud Forest Initiative.

Based in the United Kingdom, the program was launched in 1999 by a host of conservation organizations that include the United Nations Environment Program, the World Conservation Union, and the World Wide Fund for Nature. The groups are working collectively to raise awareness and promote conservation of cloud forests.

The importance of cloud forests to the year-round provision of fresh water cannot be overestimated, said Bubb. Many mountainside trees filter the water that feeds the headwaters of river systems. Cloud forests, however, capture water that would otherwise never fall to the ground as rain.

The extra water from this cloud-stripping effect amounts to 20 percent of ordinary rainfall. In mossy forests that are particularly exposed to the elements, the extra water-trapping capacity can be as much as 60 percent.

The cloud forest in La Tigra National Park in Honduras, for example, supplies 40 percent of the water consumed by the 850,000 residents of Tegucigalpa. In Tanzania, the cloud forests of the Udzungwa mountains provide water needed to operate the hydroelectric dams that supply power to Dar es Salaam.

Storehouses of Diverse Species

The provision of abundant, fresh water ought to be reason enough to conserve cloud forests. But these forests are also important because they are rich in biological diversity.

Nuñez, an ethnobiologist specializing in the plants of southern Peru, estimates that he has collected 30,000 to 40,000 plants, most of which have gone to museums for closer examination.

That amount only begins to scratch the surface. "In a small area the size of Machu Picchu, we can find the same plant diversity as on the whole continent of Europe," he said.

"So far we have described only 20 percent of the species—plants and animals—that live in this almost vertical landscape," he added.

Much of the biodiversity found in cloud forests is endemic—it can be found nowhere else. For example, most of the shrubs, orchids, and insect-eating plants found on the Cerro de la Neblina in Venezuela are unique to the mountain's summit.

"Cloud forests are habitat pockets," said Bubb. "There are different species found on each [mountain] range."

Scientists say a cloud forest's water-tapping ability can be restored by measures such as replanting.

"But restoration of the intricate mix of life-forms—of the authenticity, and of the complexity of the ecological interactions that maintain a healthy ecosystem—is simply beyond our capability," the scientific coalition notes in its publication titled Decision Time For Cloud Forests.

Bubb said the group has stepped-up efforts to raise public awareness of the need to conserve cloud forests and obtain funding for conservation strategies, such as establishing private reserves and national parks.

Meanwhile, scientists such as Nuñez are dedicated to documenting the diverse life of cloud forests and the traditional way of life of people who inhabit them, before the forests are gone.

He is aware that time is running out: "It is so easy doing research, but we have just 3 percent of the forest left."

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Forests in the Mist

Tropical montane cloud forests are high on the list of the world's most threatened ecosystems. It's widely believed that most of the remaining ones are only fragments of their original extent.

About 90 percent of mountain forests are thought to have disappeared from the northern Andes, in South America, while much attention is given to the plight of Amazonian tropical rain forests below them.

"Immediate action is required to achieve the conservation of remaining cloud forests before any more of these rare and valuable habitats are lost for good," says the Tropical Montane Cloud Forest Initiative, launched in 1999 by organizations including the United Nations, the World Wide Fund for Nature, and IUCN/The World Conservation Union.

Tropical cloud forests are found on mountains in the tropics, in areas that receive 20 to 400 inches (500 to 10,000 millimeters) of rain a year. For large, inland mountain systems, cloud forests can be found at altitudes from 6,500 to 11,500 feet (2,000 to 3,500 meters). In exceptionally humid equatorial conditions, a cloud forest zone may develop on small and steep island mountains at elevations as low as 500 meters (1,600 feet).

The persistent clouds affect the vegetation by reducing sunlight, wetting tree canopies, and suppressing evapotranspiration.

Leaves and branches draw cloud moisture, which drips to the ground and adds water to the hydrological system. Cloud forests protect watersheds by maintaining ground cover, minimizing soil erosion, and providing a regular and controlled supply of water to communities downstream.

Cloud forest soil is wet and often waterlogged, with humus and peat that make it highly organic. The forests have a profusion of epiphytes, including lichens and filmy ferns. They are exceptionally important habitats for endemic and other threatened species of flora and fauna, including many important tree species and plants such as tree ferns (Cyatheaceae) and orchids (Orchidaceae). More than a thousand species of orchids have been found in the cloud forests of Peru alone.

Most of the species in cloud forests are believed to be still unknown to science.

Many cloud forests serve as refuges for endangered species, which are being marginalized by the transformation and destruction of ecosystems at lower elevations. Large numbers of bird species and mammals, such as the spectacled bear (Tremarctos ornatus) and howler monkeys (Alouatta spp.), are dependent on cloud forest habitat for their survival.

The Tropical Montane Cloud Forest Initiative has identified 605 cloud forests in 41 countries. Most are in Latin America, especially Venezuela, Mexico, Ecuador, and Colombia.

If managed sustainably, cloud forests can provide a wide range of valuable products and services to people in the surrounding area: fuel wood, timber, and food and medicine. Cloud forests are also important for watershed protection and climate regulation.

Despite their importance, cloud forests are under pressure from threats that include human population growth and conversion of forest land for grazing and agriculture. In many areas, the extraction of wood for fuel and nonwood products has reached unsustainable levels, causing irreversible damage to the forest habitat. Hunting, tourism and recreation, road building, mining, and geothermal development schemes further add to the pressure.

Source: Tropical Montane Cloud Forest Initiative

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Use this National Geographic News article in your classroom with the Xpeditions lesson plan: Why Preserve Biodiversity?