CiiAP. Ill] TROPICAL WOODLAND AND GRASSLAND 



177 



and also in moist depressions in the ground, in the same way as in the 

 canipos. 



Only general facts arc known regarding the climate of the llanos ; 

 accurate meteorological data are wanting. Yet, from the available material, 

 the climate may be described as one hostile to tvoodland. The year is 

 divided into a quite rainless dry season of five months, which is con- 

 temporaneous with our winter and early spring, and into a rainy season, 

 which begins at the end of April. In the climate of the llanos it is 

 the dry season tliat is hostile to ivoodlaiid, for during the greater part of 

 its duration the dry easterly trade-wind blows almost continuousl)-, and 

 usually with extreme intensity, and is associated with great heat and 

 excessive dr)-ness of the air. 



A li'indy dry season is unfavourable to woodland, whereas it does no 

 harm to the thoroughly dried up prairie, whose existence is maintained 

 only in the subterranean parts of its plants, except when the season is 

 immoderatel)- prolonged. Such abnormally long periods of drought are 

 not rare, but they are far more fatal to woodland than to grassland. 



In the llanos, according to Humboldt, // rains continuously during the 

 rainy season. This directly favours the prairie, whose existence, as we 

 know, depends more on very frequent showers than on heavy ones during 

 the vegetative season. 



The following extracts from Hann's ' Klimatologie ' give the character- 

 istics of the climate of the llanos : — 



' " The clearness of the air from December until February is incomparable. The sky 

 s continuously cloudless, and the presence of a single cloud is a phenomenon that 

 engages the attention of all the inhabitants. The wind blows strongly from the east 

 uid north-east" (Humboldt). 



C. Sachs stayed at Calabozo (9°N., 150 ni. above sea-level) in the dry season (Dec. 

 :S76 until Feb. 1877). He found a morning temperature of 22-25° C. before sunrise, 

 ind 34-35° between i and 2 p.m. In February, the mean temperature between i and 

 : p.m. is 35-9°, and the relative humidity 30%, and sometimes only 16%. The east 

 rade-wind blows constantly from sunrise until noon. Complete drought prevails 

 or five months, during which there is no dew. In April the rainj' season begins, 

 ind the land that has been parched into a desert becomes clothed once more with 

 lense vegetation ' (pp. 365-6). 



The small western islands of the West Indian archipelago are occupied 

 ly woodland, which is favoured by the great humidity of the air. The 

 voodland is composed sometimes of rain-forest, as in Dominica, sometimes 

 f thorn-forest, as in St. Kitts, according as the rainfall is greater or less 

 han about 150 cm. 



I am personally acquainted with the vegetation of the two islands, regarding the 

 ainfall of which data are given below. The rainfall in Dominica, as I know from 

 xperience, is considerably heavier in the mountains, where the high-forest shows 



