486 WEST AFRICAN FORESTS AND FORESTRY 
go so far as to put a “ Ju-ju”’ on the land, which is in effect a notice 
to say that the land is of no use for a farm. However, this is usually 
forgotten in a generation, so that the same thing may happen again, 
only that insufficient time has elapsed for a proper forest to be grown, 
as the cutting of the original forest may have so altered the climatic 
factors of the locality that not only different species of trees but also 
grasses have come in, and choked nearly all the self-sown forest- 
tree seedlings. The main beneficial effects of the forest may be 
summarized as follows : 
1. The rainfall of the locality is increased, according to the figures 
of the Indian rainfall stations. This may amount to as much as 
16 to 28 per cent. increase on the annual rainfall. 
Afforestation on the Russian steppes has shown that more rain 
now falls on the planted area than in former years. 
In Western Canada it is generally said that its climate is altering, 
and a general increase of rain has been noticeable since plantations 
have been made on thousands of farms and what forests there were 
originally have been rigorously protected from annual fires. 
2. The rainfall both above and in the ground is more regularly 
distributed. 
First of all, nearly 23 per cent. of the rain which falls on the trees 
in a forest is re-evaporated into the air and does not reach the ground 
at all. This in itself increases the humidity of the atmosphere, tends 
to form clouds, and thus induces further rainfall. The clouds tend 
to protect the plants from excessive sun at what may be a critical 
period in the growing season. The extra humidity of the atmosphere 
does not necessitate the plants transpiring so much moisture as they 
would otherwise have to do, to keep them in growing condition. 
Compared to that in the open, only 22 per cent. of the amount of 
evaporation takes place in the forest, added to the fact that it occurs 
under the canopy of the trees, thus creating the more humid atmo- 
sphere which is so suitable, for instance, for the growth of cocoa and 
other such crops. In other words, we can take one hundred parts 
as the amount evaporated in the open, of which not a quarter is 
evaporated in the forest. Again, as we have seen, twice as much 
of the rainfall soaks into the ground in the forest as in the open, and 
owing to the tree-roots and general covering of the soil the water 
can only flow away gradually. On the other hand, in the open, if the 
ground is at all sloping, more than half of the rain which falls to the 
ground runs away immediately, or lies on the land, flooding it and 
making planting impossible. 
The trees then act as a rainfall distributer and also as a rainfall 
regulator. The roots of the trees act like a sponge, absorbing a great 
deal of the rainwater besides preventing it from running away. It 
has been calculated that it takes nearly six months for the rainfall 
