GOLD COAST REPORT ON FORESTS. 165 



that from all other sources, the sea included. In fact, it is prob- 

 able that a high proportion of the total rain precipitated on the 

 surface of the earth consists of the condensed vapour transpired 

 by plants. The vapour may not always be condensed in the 

 actual vicinity of the forests from which it is transpired, but it is 

 in all probabilit3' condensed somewhere else, and that place has to 

 thank the forests for their contribution to its rainfall. 



In this connection a very interesting article in the October 

 number (1908) of the '' Indian Forester" should be consulted. 



Kumasi is a good example of a locality in which a compara- 

 tively poor rainfall (52'77 inches) is associated u-itli tin' presence 

 of extensive evergreen forests and a high relative humidity of 

 86'27 per cent. 



There is but little doubt that here the high relative humidity, 

 and the copious water supply which this ensures, are directly 

 attributable to the existence of these immense forests. An 

 annual rainfall of only 52 inches would, in the absence of such 

 forests, be totally inadequate in a tropical region like that of 

 the Gold Coast to support the type of vegetation that actually 

 does exist round Kumasi. The exposed soil (in the absence of 

 the forests) would be rapidly deprived of its moisture during the 

 Harmattau season, and this would re-act on the vegetation, and 

 the latter would then acquire a more or less xerophilous habit. 



For practical purposes it is immaterial to enquire whether in 

 the first instance the humidity of the air favoured the growth 

 of the forests or the growth of the forests produced the humidity. 

 Humidity cannot be voluntarily influenced by any means known 

 to man, except by afforestation and deforestation; for the effects 

 of irrigation are negligible in comparison with the effects 

 brought about by forests, so far, at least, as the humidity of the 

 atmosphere is concerned. 



Forests, once they have been started, whatever their origin, 

 to a large extent mould their own destinies, and gradually 

 change the climatic and other factors of the adjacent lands in a 

 manner suitable for the further spread of such vegetation, pro- 

 vided, of course, that they are not interfered with by man. 



No one who has actually experienced the change brought 

 about in his sensations, when stepping from the cool and grateful 

 shade of a tropical forest into the fierce diy heat of an adjacent 

 treeless plain, can fail to realise what the existence of such a 

 forest means to the locality, and can ever entertain any doubts 

 afterwards as to its beneficial action on the soil and climate. 



The Soil. 



The most prevalent soil of the country is a red sandy loam, 

 coloured by the presence in it of ferric oxide. The amount of 

 sand in the clay varies in different localities, but has no marked 

 effect on the vegetation within the maritime forest zone and the 

 heavy rainfall associated with it. Outcrops of laterite are also 

 frequently met with in the same region, but the edaphic in- 

 fluences due to such changes in the soil are completely ovor- 



