What Is the Importance of a Cloud Forest?
An important feature of cloud forests is the tree crowns can intercept the wind-driven cloud moisture, part of which drips to the ground. This fog drip occurs when water droplets from the fog adhere to the needles or leaves of trees or other objects, coalesce into larger drops and then drop to the ground.
It can be an important contribution to the hydrologic cycle. Due to the high water content of the soil, the reduced solar radiation and the low rates of decomposition and mineralization, the soil acidity is very high, with more humus and peat often forming the upper soil layer.
Cloud forests support a wide variety of species of trees, plants, and animals. For this reason, scientists are studying them in more depth than they have in the past. Threats from climate change and deforestation has led many conservationists to focus on cloud forests to prevent their decline.
In 2004, an estimated one-third of all cloud forests on the planet were protected at that time. Because of the cloud-stripping strategy, the effective rainfall can be doubled in dry seasons and increase the wet season rainfall by about 10%. Experiments of Costin and Wimbush (1961) showed that the tree canopies of non-cloud forests intercept and evaporate 20 percent more of the precipitation than cloud forests, which means a loss to the land component of the hydrological cycle.
Tropical montane cloud forests are not as species-rich as tropical lowland forests, but they provide the habitats for many species found nowhere else. For example, the Cerro de la Neblina, a cloud-covered mountain in the south of Venezuela, accommodates many shrubs, orchids, and insectivorous plants which are restricted to this mountain only.
The endemism in animals is also very high. In Peru, more than one-third of the 270 endemic birds, mammals, and frogs are found in cloud forests. One of the best-known cloud forest mammals is the mountain gorilla. Many of those endemic animals have important functions, such as seed dispersal and forest dynamics in these ecosystems.
In 1970, the original extent of cloud forests on the Earth was around 50 million hectares. Population growth, poverty and uncontrolled land use have contributed to the loss of cloud forests. The 1990 Global Forest Survey found that 1.1% of Tropical Mountain and highland forests were lost each year, which was higher than in any other tropical forests.
In Colombia, one of the countries with the largest area of cloud forests, only 10-20% of the initial cloud forest covers remain. Significant areas have been converted to plantations, or for use in agriculture and pasture. Significant crops in montane forest zones include tea and coffee, and the logging of unique species causes changes to the forest structure.
A cloud forest, also called a fog forest, is a generally tropical or subtropical, evergreen, montane, moist forest characterized by a persistent, frequent or seasonal low-level cloud cover, usually at the canopy level, formally described in the International Cloud Atlas (2017) as silvagenitus. Cloud forests often exhibit an abundance of mosses covering the ground and vegetation, in which case they are also referred to as mossy forests. Mossy forests usually develop on the saddles of mountains, where moisture introduced by settling clouds is more effectively retained.
Annual rainfall can range from 500 to 10,000 mm/year and mean temperature between 8 and 20 °C. While cloud forest today is the most widely used term, in some regions, these ecosystems or special types of cloud forests are called mossy forest, elfin forest, montane thicket, and dwarf cloud forest.
Important areas of cloud forest are in Central and South America, East and Central Africa, Indonesia, Malaysia, the Philippines, Papua-New Guinea, and in the Caribbean. Although far from being universally accepted as true cloud forests, several forests in temperate regions have strong similarities with tropical cloud forests. The term is further confused by occasional reference to cloud forests in tropical countries as “temperate” due to the cooler climate associated with these misty forests.
In comparison with lower tropical moist forests, cloud forests show a reduced tree stature combined with increased stem density and generally the lower diversity of woody plants. Trees in these regions are generally shorter and more heavily stemmed than in lower-altitude forests in the same regions, often with gnarled trunks and branches, forming dense, compact crowns.
Their leaves become smaller, thicker and harder with increasing altitude. The high moisture promotes the development of a high biomass and biodiversity of epiphyte, particularly bryophytes, lichens, ferns (including filmy ferns), bromeliads and orchids. The number of endemic plants can be very high.