Manual de Plantas de Costa Rica | The physical environment 79 
Strand vegetation (Ipomoea pes-caprae, 
Hippomane mancinella, Bromelia pinguin) 
communities. G6mez P. (1986) listed Agave (Agavaceae), Dioscorea (Dioscoreaceae), 
and the fern genera Anemia (Schizaeaceae) and Notholaena (Pteridaceae) as limestone 
“indicators” in Costa Rica, and Bursera (Burseraceae) and Melocactus (Cactaceae) as 
indicative of serpentine. He characterized aluminum-rich soils by the predominance (at 
low elevations) of Melastomataceae, Rubiaceae, and many ferns, or (at higher eleva- 
tions) of Quercus (Fagaceae) and Comarostaphylis (Ericaceae). Savannas with iron- 
rich soil ostensibly support Evolvulus (Convolvulaceae) and Polygalaceae, those with 
aluminum-rich soil Burmannia capitata (Burmanniaceae). 
See Holdridge et al. (1971) for detailed soil data on 46 sites scattered throughout 
Costa Rica, together with characterizations of vegetation. 
Climate and weather 
Climate is the sum of weather conditions for a particular region (Coen, 1983). Gener- 
ally speaking, the weather in tropical regions is much less variable, at any given site, 
than at higher latitudes (Coen, 1983). For example, in Costa Rica, at ca. 10°N latitude, 
the average temperature of the warmest month does not exceed the average tempera- 
ture of the coolest month by more than 5°C at a given site (Coen, 1983). However, be- 
cause Costa Rica is a relatively narrow isthmus and topographically complex, it ex- 
hibits great climatic variation, often over short distances. As pointed out by Gomez P. 
(1986), one of the driest sites in the country (El Guarco) is just 18 km removed from 
one of the wettest sites (Tapanti), in Cartago Province. 
Average maximum monthly temperatures at sea level in Costa Rica are ca. 32.6°C 
on the Pacific side and ca. 29.9°C on the cloudier Caribbean side (Coen, 1983). Ac- 
