|Cloud Forests in the Humid Tropics: A Bibliographic Review (UNU, 1987, 81 pages)|
Cloud forests have always been a fascinating topic for scientists of various disciplines such as geographers, climatologists, meteorologists, forest ecologists, botanists, zoologists, hydrologists, and conservationists in general. One cannot help but be impressed upon entering these forests, a pastiche of the mysterious and the enigmatic, with their abundance of epiphytes, especially mosses, bromeliads and orchids, the presence of peculiar insects, reptiles, mammals, and birds such as the magnificent quetzal.
This scientific and multidisciplinary topic attracted the attention of the United Nations University (UNU), of Tokyo, which commissioned CATIE's bioclimatologist, Thomas Stadtmuller, to undertake a study on the subject. It would review the state of the art as a basis for generating new scientific effort, especially that which could be carried out as part of a worldwide network.
However, interest reaches beyond pure science. Cloud forests contribute additional water through what is known as "horizontal precipitation" which adds from 7% to as much as 158% of rainfall, as indicated in table 2 of this publication. In addition to the significant increase in precipitation, there are other regulatory effects, particularly regarding maintenance of the habitat of endangered species and possibilities of using this water for commercial ends.
Reading this document one is made aware that there are many kinds of cloud forests, occurring at elevations of less than 500 and up to 3,900 metres above sea level.
It is a tragedy that these cloud forests are disappearing as part of a worldwide conversion of tropical forests to other uses: it is estimated that only 500,000 square kilometres remain in the humid tropics.
After studying the location, ecology, composition, structure, and important climatic and hydrological aspects of tropical cloud forests, the author makes important conclusions and recommendations. Above all, he points out the gaps in our knowledge, such as the lack of quantification of horizontal precipitation over large areas, the role of epiphytes, effects on plant physiology, and local and regional hydrology. This last point is especially critical, since it influences water supplies vital to downstream areas.
It is eloquently argued that certain cloud forests should be totally protected while for others partial protection should suffice. This task falls less upon the scientist than the decision-maker, be he or she at the national or international level, with sufficient time, money, and multidisciplinary back-up to succeed.
Drawing from more than two hundred references, this present work summarizes the state of existing knowledge while at the same time highlighting what remains to be learned. It is hoped that this document will prove of great utility to those working or considering working on the subject of cloud forests, as well as to decision-makers. It should not only foster progress in different scientific fields of study, but above all be used to facilitate concrete actions and decisions which will ensure that this unique treasure remains to be benefitted from and enjoyed by future generations, preserving one of the many mechanisms that govern our biosphere.
Gerardo Budowski, Ph.D.
Head, Department of Renewable
Turrialba, March 5,1986
"At these elevations between 2,500 and 3,500 metres above sea level, the traveller finds himself constantly surrounded by a dense fog. This precipitation (or this mysterious formation of water?) that could be the result of a strong electrical tension, gives the vegetation a verdent colour which is continously renewed."
Alexander von Humboldt in 1807 about high mountain vegetation in Colombia and Ecuador.