What Is A Cloud Forest?

Looking down from Phuyupatamarca on the Inca Trail, into a cloud forest where a silver river winds through the lush green jungle and clouds.

Cloud Forests (montane rainforests) refer to the vegetation of tropical mountainous regions where there is heavy rainfall and persistent condensation resulting from the cooling of the moisture being pushed upwards by the mountains. They are usually characterized by a persistent, frequent and seasonal low-lying layer of mist and cloud cover usually at the canopy level. Cloud forests are rare since the exceptional conditions that create these forests are only found in tropical areas with tall mountains.

Contents:

Location Of Cloud Forests

Cloud forest distribution map
Map showing the distribution of the world's cloud forests.

Due to their unique characteristics, cloud forests are usually found along the sides of the mountains at elevations of between 3000 and 10000 feet but as low as 1650 feet in the Tropics between coordinates 23°N and 23°S. Only 1% of the global woodlands are considered as cloud forests following a decline from 11% in the 1970s due to interferences by human activities and global warming. Areas where these forests form include southern Mexico, Africa, Southeast Asia, Madagascar, Central America, the Caribbean, New Guinea and South America. The World Conservation Monitoring Centre has identified 736 cloud forests distributed in 59 countries. Of these 327 have been classified as protected areas since 2002.

Factors Needed For The Growth Of Cloud Forests

The presence of cloud forests is dependent on the local climatic conditions which are influenced by distance to the sea, the exposition, elevation from the sea level, and latitude coordinates. Beyond these natural conditions, there are small bands of elevations in which the atmospheric conditions are suitable for the formation of cloud forests. These conditions are characterized by persistent fog at the vegetation level resulting in the reduction of direct sunlight hence evapotranspiration takes place. Although not universally accepted as true cloud forests, temperate cloud forests can occur at such elevations in temperate regions.

The Hydrological Cycle

La Fortuna Falls
Tourists and locals visiting the La Fortuna waterfall. This scenic waterfall is located in the cloud forest of Tenorio Volcano National Park in Costa Rica. Editorial credit: Nick Fox / Shutterstock.com

The layer of clouds and mist occurring in cloud forests form through the evaporation of water forming warm air masses. The air mass is carried upwards by the wind currents until it strikes the sides of the mountain and are deflected upwards due to the naturally sloping land. As the air masses rise towards the mountains, they begin to cool. The moisture in the air masses condenses and begins to cool forming clouds and mist. Forests that exist within these unique conditions tend to be different form forests in lower elevations

Characteristics Of Cloud Forests

Ecuadorian cloud forest
Inside the Ecudorian cloud forest.

Cloud forests form an ecosystem characterized by dense forests and shorter trees, coupled with increased stem density and a lower diversity of woody plants. The trees here are generally shorter and their leaves become thicker, harder, and smaller as the altitude increases.

The diffuse light, high humidity, and crooked tree trunks with twisting branches provide a conducive environment for the growth of epiphytic plants. The most famous of the epiphytes include orchids which adorn the tress with flowers of every shape color, and size, lichens, ferns, bromeliads, and bryophytes. The tree crowns intercept the wind driven cloud moisture, which drops in the form of fog. Fog drips usually occur when water droplets cling to the needle-shaped leaves and accumulate to large drops that drop to the ground, thus contributing to the hydrological cycle.

Orchids photographed during a walk in the cloud forest in Ecuador.

As natural water towers, cloud forests provide fresh and clean water to billions of people around the continents where they are found. By taking up the mist that forms above their canopies, they release this moisture gradually into small creeks that feed streams and the rivers. Even though rains are highly seasonal, these misty covers feed the tropical waterways. During heavy storms, the forest topography prevents the occurrence of mudslides that would cause extensive destruction of the ecosystem.

A river flowing through the lush green vegetation of Monteverde's cloud forest in Costa Rica.

Soil acidity in cloud forests is high due to the high-water content present in the soil, reduced sunlight, and slow rate of decomposition and mineralization. A layer of humus and mulch usually forms in the upper layer of the soil to control runoff during high precipitation. Annual rainfall within the cloud forest regions ranges from 500 to 10,000 mm/year and the mean temperatures averaging 46- and 68-degrees Fahrenheit.

Difference Between Cloud Forests And Rainforests

Oftentimes, the definition of cloud forests can be ambiguous with most countries adopting the terms Afromontane and upper montane rain forests to refer to these ecosystems. As such there is a confusion between rainforests and cloud forests. The two are different ecosystems where rainforests refer to tropical forests with an annual rainfall of 100 inches with trees forming a canopy. Cloud forests are a type of rainforests but with altitudes higher than 3000 feet and characterized by an overwhelming number of epiphytes among the large trees. The distinguishing characteristics are the elevations at which each ecosystem thrives and the cloud over found in the cloud forests.

Flora And Fauna Of Cloud Forests 

Shy high altitude Andean colorful Plate-billed Mountain Toucan perched on mossy branch among bromeliad flowers in typical environment of cloud forest.

Cloud forests are rich biodiversity areas rich in flora and fauna that in some cases are unique to these ecosystems.  In the south of Venezuela, the forests accommodate shrubs orchids, and insectivorous plants that are restricted to this mountain. The canopies provide a home to epiphytic plants including bromeliads, aroids, and ferns. Some of the epiphytic plants begin their lives a seed deposited on top of other trees in the canopy and grow to become full-sized trees.

The abundance of flowering plants in the upper reaches of these ecosystems provide a habitat with a wide range of fruits, nesting sites for birds, hollow tree cavities where large larger mammals breed, and water pockets that act as breeding grounds for tadpoles. Begonias and herbaceous plants many grow to exceptionally large size where there are clearings.

Baird's Tapir in cloud forest of Costa Rica.

These forests are home to over 270 species of frogs, birds and mammals. The Spectacled Bear is one of the mammals that is found in cloud forests. There are large flocks of gaudily-decorates tanagers that flit across the slopes in search fruits. The hummingbird, ochre-fronted antpitta, and the rare long-whiskered owlet are present in these ecosystems and are classified as threatened species. They also harbor the endangered yellow tailed wooly monkey and the long--imbed salamander that preys upon shredding invertebrates hence maintaining the forest's carbon cycle.

Central American agouti in Monteverde Cloud Forest Reserve, Costa Rica.

The Geoffrey’s Spider monkey, considered as the third most intelligent nonhuman primate, is endemic to cloud forests. This species has an incredible mental capacity that allows it to recognize and remember the different fruits in the forests and their exact locations. Jaguars are also widely spread in the Central American cloud forest undergrowth and usually hunt the spider monkeys. Generally, a mutualistic relationship exists among the fauna and flora of cloud forests hence forming a rich tapestry of life that continues to diversify over the years.

Threats To Cloud Forests

Deforestation in the mountains of Colombia.

Cloud forests represent a rare and fragile ecosystem that is under threat in many parts of the world. In the 1970s, the extent of cloud forests is believed to have been approximately 50 million hectares. Exponential population growth, poverty, and uncontrolled land use over the decades are attributed to the decline of these ecosystems. Based on a research conducted by the Global Forest Survey in 1990, it is approximated that 1.1% of the tropical and highland cloud forests are lost each year. In countries like Colombia, one of the countries with extensive covers of rain forests have lost close to 80% of these ecosystems to deforestation to pave way for human settlements, logging, and infrastructural developments.

Logging in the Malaysian montane forests leading to wanton deforestation of the region.

Another major threat to the existence of cloud forests is the impact of climate change. Since they are heavily reliant on local climates, the current global climate change which has affected the water tables is likely to lower the amount of evaporation required for the formation of the clouds. As a result of the destruction of the ozone layer, increased temperatures inhibit the condensation of water evaporate forms the mist and fog over the canopies. It is estimated that in the next 70 years, the extent of environmentally suitable areas for the formation of cloud forests in countries like Mexico will be completely lost.

Linked to the reduced cloud cover, the hydrological cycle will change leading to the drying out of the system. This will result to wilting and loss of epiphytes, which are heavily dependent on humidity. Vertebrates’ dominant to this region will become extinct due to increased drought and loss their natural habitats. Hurricanes are likely to increase thus damaging the tropical montane cloud forests, loss of biodiversity, altitude shifts and a complete loss of the cloud cover in some regions.

Conservation Efforts

A tourist hiking in the cloud forest in Monteverdo, Costa Rica.

Under the UN Environmental Program World Conservation Monitoring Centre, 327 cloud forests have been classified as protected areas to help protect and conserve these ecosystems. The Andean cloud forests in particular are a top priority for biodiversity conservation due to the endemic plant and animal species found within their ecosystems.

Due to the unique conditions under which these forests thrive, it is difficult to replicate them in artificial habitats. It is expensive to maintain high temperatures and high humidity without attracting algae and fungi. However, botanical gardens in Singapore and San Francisco have tried to imitate the natural conditions of cloud forests hence promoting growth of plants including ferns orchids, and clubmosses. 

Share

More in Environment