Cloud forests

DEFINITION: Forests on moist tropical mountain slopes covered by tree-level clouds.

Cloud forests are rich in biodiversity and act as important sources of water conservation. These valuable forest ecosystems are strongly threatened by human activity, particularly by deforestation, unsustainable agricultural use, and overharvesting of plants and animals.

Cloud forests cover humid tropical mountain slopes ranging from Central and South America to Africa, South and Southeast Asia, Papua New Guinea, and Pacific islands such as Hawaii. They are created when moist air meets mountain barriers and forms clouds covering the treetops. Because of prevailing wind directions, cloud forests generally cover eastern mountain slopes. They typically are found on mountains that range between 1,200 and 2,500 meters high (4,000 to 8,200 feet), but some cloud forests can be found on peaks as low as 300 meters (1,000 feet) on Pacific islands and as high as 3,500 meters (11,500 feet) in the Andes of South America and the Ruwenzori range of Uganda.

The higher the cloud forest, the smaller the trees tend to be, and the thicker and more gnarled are their stems and branches. The leaves of the trees are generally tough and small. The trees host a great variety of epiphytes (other plants that grow on them), such as bromeliads, lichens, orchids, mosses, and ferns. The soils are very moist and rich in organic material, as they contain much humus and peat.

Cloud forests function as unique watersheds. The leaves on the top branches of the trees catch the moisture of the clouds driven there by the wind and let it drip to the forest floor. This process, scientifically called occult precipitation and popularly known as cloud stripping, accounts for doubling rainfall in dry seasons and still increasing it by about 10 percent in wet seasons when compared to areas outside the cloud forests. Cloud forests also act as water reservoirs, preventing runoff during rain and supplying a steady flow of water in dry times.

Cloud forests have come under severe threat from human activity. According to a publication by Yale News, there are tropical cloud forests in sixty countries, but they account for under 1 percent of land on Earth. By the early 2020s, the publication reported, about 8 percent of some forests had been lost to logging and farming. This threatened the survival of about two thousand species of plants and animals that live only in these forests. In addition to this, unsustainable harvesting of plants such as rare orchids and ferns, and the trapping and hunting of amphibians, birds, and mammals unique to the cloud forests, threaten to destroy these ecosystems and lead to species extinction.

Initially, cloud forests enjoyed some natural protection because of their inaccessibility and the poor quality of their soil and timber for human use. As farmers, loggers, and ranchers over-exploited the tropical forests below cloud forests, they shifted their attentions upward into the cloud forests. The most severe threats to cloud forests are deforestation for cropland and tree cutting for fuel wood. In addition, in the Andes, the use of cloud forests for the planting of illegal crops such as coca (from which cocaine is derived) remained another threat. Even tourism and recreation can threaten cloud forests if these are undertaken in an ecologically unsound manner.

By the twenty-first century, environmentalists, policymakers, and the public had grown increasingly aware that cloud forests need to be protected from degradation by humanity. The successful management of sustainable use of these forests continued to depend on the participation of the forests’ Indigenous populations and on the creation of both economic incentives and legal sanctions supporting the forests’ protection.

Bibliography

Gradstein, S. Robbert, et al., editors. The Tropical Mountain Forest: Patterns and Processes in a Biodiversity Hotspot. Universitätsverlag Göttingen, 2008.

Haber, William. An Introduction to Cloud Forest Trees. 2nd ed., Mountain Gem, 2000.

Hathaway, Bill. "Despite Protection, Dramatic Losses of Cloud Forest Ecosystems and Species." Yale News, 29 Apr. 2021, news.yale.edu/2021/04/29/despite-protection-dramatic-losses-cloud-forest-ecosystems-and-species. Accessed 15 Sept. 2025.

Peters, Michelle. "A Walk in Costa Rica's Monteverde Cloud Forest." Natural Habitat Adventures, 22 May 2022, www.nathab.com/blog/costa-ricas-monteverde-cloud-forest/. Accessed 15 Sept. 2025.

Scatena, F. N., and L. S. Hamilton. Tropical Montane Cloud Forests: Science for Conservation and Management. Cambridge UP, 2010.

“Tropical Cloud Forests Are Shrinking.” E. O. Wilson Biodiversity Foundation, 21 June 2021, eowilsonfoundation.org/news-posts/tropical-cloud-forests-are-shrinking/. Accessed 15 Sept. 2025.