GOLD COAST. REPORT ON FORESTS. 11 



done in two instances close to Aburi, where, according to the 

 natives, an abundant supply of water was formerly available. 

 Concurrently with this diminution of the moisture held in sus- 

 pension by the soil, the character of the vegetation alters, 

 plants characteristic of drier regions gradually occupy the land 

 and replace those typical of the evergreen hill forests, and 

 slowly but surely the whole aspect of vegetation changes. Once 

 the forests become dry and deciduous they are more than ever 

 exposed to damage from, forest fires, and any clearings made in 

 them for farming purposes are eventually occupied by various 

 species of grasses. When this stage is reached it may be said 

 that the end of forest vegetation is close at hand. 



1 uder existing agricultural practice there is nothing what- 

 ever to stop the gradual spread of the arid country into the 

 very heart of the forest region and that is what will undoubtedly 

 take place unless efficient barriers against its spread are created. 

 Such barriers are even now available, provided that the forests 

 occupying the hill ranges which border the arid plains are 

 strictly protected against farming and against forest fires. The 

 protected area should include the catchment basins on the left 

 banks of the upper reaches of the Densu and Birrim Rivers. 

 Behind this barrier and under its protection the cultivation of 

 such plants as cocoa, cola, &c., W'hich require a moist climate, 

 can 'be carried on in safety, as they will no longer be exposed to 

 the direct action of the arid regions. 



As matters now stand there is every indication that the cocoa 

 plantations on the hills facing the plain are doomed to destruc- 

 tion at an early date. The vegetation here is already altering in 

 character from the evergreen to the deciduous type, and the 

 change is so pronounced that the Acting Director of Agriculture 

 estimates the life of a cocoa tree at not more than six or seven 

 years in this locality. What is more important, however, is the 

 fact that the damage is not likely to end here. The process of 

 substitution will progress till the very heart of the forest country 

 is involved. Such changes will jeopardise the palm-oil industry 

 as well as bring 'about a general reduction in the fertility of the 

 soil. 



The changes described above have been retarded to a certain 

 extent 011 the main Aburi range by the fact that this range is of 

 sufficient altitude (1,600 feet) to condense the water vapour held 

 in suspension by the moist sea breezes when the latter strike it 

 and are forced up the slopes facing the sea. 



This condensation is very marked at night and gives rise to 

 the dense, dripping mists that are such a noticeable feature of 

 the Aburi Hills even at the driest season of the year. Such 

 night mists are very favourable to plant growth, especially in 

 the tropics ; they must have an appreciable effect in delaying the 

 progress of the usual changes that follow the destruction of 

 forests in hot climates. Nevertheless, beneficial as they are, 

 they can never compensate for so decided a diminution of the 

 rainfall as has apparently taken place at Aburi during the last 

 eight years. 



The rainfall records of this station for the sixteen years 1892 

 to 1907 show that the average rainfall for the first period of 



