The ecological geography of cloud forest in Panama

"The physiography, climate, and major vegetational regions of Panama are discussed, with particular reference to factors that influence the distribution and nature of cloud forest. Difficulties were encountered in applying the Holdridge classification of life zones or world plant formations to the natural regions of Panama, and it is concluded that other systems are at least easier to use in the field. The extensive cuipo forests (Cavanillesia plantanifolia association) of eastern Panama are thought to be largely the result of edaphic factors associated with the nearly base-level terrain, rather than being primarily the result of climatic control as suggested in recent life zone maps. Cloud forest is thought of as a habitat or community-type in a very broad sense, but the term will not be useful for all purposes and usually needs to be qualified. A cloud forest is any montane forest that owes its character primarily to the atmospheric conditions associated with frequent, enshrouding clouds, even though such forests may be quite diverse by floristic and some physiognomic criteria. The vegetation tends to be conspicuously lusher than in adjacent zones of little or no cloud formation and usually there is a profuse growth of epiphytes. Known cloud forests in Panama are mountaintop and ridge phenomena and do not give way to higher vegetational zones; exceptions probably occur on the unexplored Cerro Santiago, and possibly on the north face of Volcán de Chiriquí, the two highest mountains in Panama. Grassy savannas above a reputed cloud forest in the Azuero Peninsula probably were caused by the activity of man. Cloud forest first occurs on mountains at the unusually low elevation of 750 meters in eastern Panama and at 2200 meters on higher mountains in western Panama. These forests may be confined almost to the crest of a ridge or extend as much as 300 meters in elevation down the side of a mountain and, in the latter case, there may be distinct subzones, including elfin woodland. Panamanian cloud forests are briefly described and pictured herein, and are discussed in various generalities that probably apply to cloud forests in other places. Some ecological implications of the various topics are illustrated by a few selected plant and animal examples. Cloud forests that border on significantly drier zones (e.g. evergreen seasonal forest on steep slopes) provide at least partial genetic isolation for organisms having high moisture requirements, as is suggested by populations of certain Panmanian frogs. Cloud forests that border on zones equally as wet (i.e., montane rain forest) are perhaps of less ecological and evolutionary importance"--P. 49-50.