cloud forests - time
Philip Bubb is an Adviser with
the United Nations Environment Programme's
World Conservation Monitoring Centre
Mark Aldrich is a Forest Officer with
the Forests for Life programme of the World
Wide Fund for Nature (WWF).
Jeff Sayer is Senior Associate of the WWF
and World Conservation Union (IUCN)
Commission on Ecosystem Management.
A threat to the cloud forest: on the slopes of the volcanoes Santa Isabel and El Ruíz just outside Los Nevados National Park in Colombia (altitude approximately 2 500 m), trees have been cleared for cattle raising and agriculture
- W. FERWERDA
Cloud forests, defined as forests whose ecology and physiology are tied to their direct contact with clouds, occur on mountain slopes and ridges that are frequently bathed in clouds and mist. They are found in over 60 countries and on many tropical islands. The trees are often dwarf and twisted and covered with an abundance of epiphytic mosses, orchids and ferns. Tree ferns and primitive gymnosperms such as the Podocarpacae are common. The most significant feature of cloud forests is their role in capturing the water that condenses on the vegetation. Although the claims for the hydrological benefits of forested catchments are often exaggerated, there is considerable evidence that cloud forests really do increase supplies of water (Bruijnzeel, 2000; Bruijnzeel and Hamilton, 2000). The regular and year-round supply of clean water from cloud forests is a vital resource for many upland communities and lowland cities.
Cloud forests occur in over 60 countries, but because they are rarely distinguished as a forest type it is difficult to determine their total area. It is certainly small: cloud forests are a portion of the 1.6 percent of the world's closed forests that are tropical moist mountain forests between 1 500 and 3 500 m, which cover 539 263 km2 (Kapos et al., 2000).
One of the characteristics of cloud forests is that they have exceptional numbers of endemic species. For example, in Mexico, cloud forests cover less than 1 percent of the country but contain about 12 percent of the country's plant species with 30 percent of these endemic to Mexico (Rzedowski, 1996). In western Ecuador a single cloud forest ridge was found to contain about 90 plant species apparently endemic to a forest area of only 20 km2 (Gentry, 1992). The mountain gorilla in the Virunga volcanoes in Rwanda and Zaire and the brilliantly coloured bird known as the resplendent quetzal (Pharomachrus mocinno) in Central America are endemic to cloud forests and are major tourist attractions. Cloud forests harbour wild relatives of papaya, tomato, avocado, Phaseolus beans, cucumber, potato and peppers. The Cascarilla tree (Cinchona succirubra), from which the anti-malarial drug quinine was extracted, is native to the cloud forests of Ecuador.
Cloud forests tend to be naturally dispersed in fragments on mountain tops and are very susceptible to further fragmentation by deforestation and road building. They are principally threatened by clearance for farming and cattle raising. The cultivation of temperate-zone vegetables, fruits and flowers for export is a growing threat. Cloud forests appear to be especially susceptible to climate change, with evidence that warming may cause a lifting of the cloud base above the altitude of the forest (Foster, 2001). The consequent drying-out of the forest has been linked to the extinction of the golden toad and other amphibians, and to declining stream flows in the Monteverde cloud forest in Costa Rica (Pounds, Fogden and Campbell, 1999). Nevertheless, cloud forests have often been overlooked in conservation plans.
Cloud forests are ideal sites for testing mechanisms for payment for the environmental service of clean water, which flows from the forest year-round. In Latin America a number of projects are testing schemes in which users of water from cloud forests are taxed to pay for conservation programmes. Cloud forests in several parts of Latin America support profitable private tourist ventures. However, in Africa and Asia the value of cloud forests has largely gone unrecognized.
As a contribution to the International Year of Mountains, the United Nations Environment Programme's World Conservation Monitoring Centre (UNEP-WCMC), the World Wide Fund for Nature (WWF), the World Conservation Union (IUCN) and the United Nations Educational, Scientific and Cultural Organization (UNESCO) International Hydrological Programme are collaborating in a Tropical Montane Cloud Forest Initiative. Its objective is to increase recognition and resources for cloud forest conservation around the world, with an emphasis on their role in providing freshwater. A global database of cloud forest sites is being developed and networks of cloud forest conservation specialists are being established. The Commission on Ecosystem Management of IUCN is planning further studies of the unique hydrological and biodiversity values of cloud forests, with special attention to the threats posed by climate change. For further information consult the Web site of UNEP-WCMC (www.unep-wcmc.org/forest/cloudforest/english/homepage.htm) or contact Philip Bubb (firstname.lastname@example.org) or Mark Aldrich (email@example.com).
Bruijnzeel, L.A. 2000. Hydrology of tropical montane cloud forests: a re-evaluation. In J. S. Gladwell, ed. Proceedings of the Second International Colloquium on Hydrology of the Humid Tropics. Panama City, Panama, CATHALAC.
Bruijnzeel, S. & Hamilton, L.S. 2000. Decision time for cloud forests. IHP Humid Tropics Programme Series No.13. Paris, France, United Nations Educational, Scientific and Cultural Organization (UNESCO).
Foster, P. 2001. The potential negative impacts of global climate change on tropical montane cloud forests. Earth Science Reviews, 55(1-2): 73-106.
Gentry, A.H. 1992. Diversity and floristic composition of Andean forests of Peru and adjacent countries: implications for their conservation. Memorias del Museo de Historia Natural, UNMSM, 21: 11-29.
Kapos, V., Rhind, J., Edwards, M., Price, M.F. & Ravilious, C. 2000. Developing a map of the world's mountain forests. In M.F. Price and N. Butt, eds. Forests in sustainable mountain development - a state of knowledge report for 2000, p. 4-9. IUFRO Research Series No. 5. Oxford, UK, CAB International.
Pounds, J.A., Fogden, M.P.L. & Campbell, J.H. 1999. Biological response to climate change on a tropical mountain. Nature, 398: 611-615.
Rzedowski, J. 1996. Análisis preliminar de la flora vascular de los bosques mesófilos de montaña de México. Acta Botanica Mexicana, 35: 25-44.