Cloud forests are unique tropical or subtropical forests characterized by persistent low-level cloud cover, often at the canopy height. These distinct rainforest ecosystems are defined by specific atmospheric conditions that create a perpetually misty and humid environment. This constant moisture shapes the entire forest, from the types of plants that flourish to the animals that call it home.
The Misty Environment
The defining feature of a cloud forest is its constant immersion in mist and fog, which occurs when moisture-laden air currents are pushed upwards by mountains, cooling and condensing into clouds at specific altitudes. This phenomenon, often called “horizontal precipitation” or “fog drip,” allows vegetation to capture water directly from the air, even when it is not raining. Water droplets condense on leaves and branches, then drip to the forest floor, contributing significantly to the forest’s water supply. This atmospheric moisture leads to high humidity (often exceeding 90%) and cooler temperatures compared to lowland rainforests, typically ranging from 8°C to 20°C. The high water content in the soil, coupled with reduced sunlight due to the persistent cloud cover, results in acidic soil conditions and slower decomposition rates.
Life Adapted to the Clouds
The consistently humid and cool conditions within cloud forests foster a distinct array of plant and animal life. Trees in these environments are often shorter and more gnarled than their lowland counterparts, with dense, compact crowns and smaller, thicker leaves. Epiphytes, plants that grow on other plants, are abundant and diverse, covering tree trunks and branches in thick layers. These include mosses, lichens, ferns, bromeliads, and orchids, which absorb water and nutrients directly from the humid air. The presence of these epiphytes also increases the forest’s ability to intercept cloud moisture and contribute to the hydrological cycle.
The unique microhabitats created by the dense epiphyte growth support a variety of animal species. Cloud forests are home to numerous endemic species, found nowhere else on Earth. For instance, more than a third of Peru’s endemic birds, mammals, and frogs inhabit cloud forests. The spectacled bear, the only bear species in South America, is one such mammal found in these misty ecosystems. The high humidity also benefits amphibians, which thrive in the moist conditions.
Where Cloud Forests Thrive
Cloud forests are geographically restricted, typically found in tropical and subtropical mountainous regions at elevations. While altitude can vary, they generally occur between 1,000 and 2,500 meters (3,000 to 8,000 feet) above sea level. These forests are not common globally, making up only about 1% of the world’s woodlands.
Prominent regions with cloud forests include Central and South America, particularly the Andes Mountains, Costa Rica, and parts of Mexico. They are also found in Southeast Asia, East Africa, and parts of the Caribbean and New Guinea. The presence of cloud forests depends on factors such as proximity to the sea, exposure to moisture-laden winds, and elevation ranges where clouds consistently form at the canopy level.
Why Cloud Forests Matter
Cloud forests play a significant role in regional and global ecosystems, primarily due to their water regulation function. Often called “water towers,” they capture atmospheric moisture and release it slowly into rivers and streams. This process provides a consistent water supply to lowland communities and cities, even during dry periods. For example, the cloud forest of La Tigra National Park in Honduras supplies 40% of the water for Tegucigalpa, its capital city.
Beyond water provision, these forests are important centers of biodiversity, harboring a high concentration of unique species. Although they may not always have the highest species richness compared to lowland rainforests, their high levels of endemism make them irreplaceable habitats. The diverse life within cloud forests contributes to the overall stability of regional climates and ecosystems.