54 SYLVICULTURE IN THE TROPICS 



PT. I 



to similar circumstances, and it becomes necessary for 

 the forester to study his own forest flora, and not to 

 try to introduce into such localities such species as 

 are unable to struggle against stagnant humidity of 

 the soil. 



We have already seen that the effect of some winds 

 in the Tropics is to bring rain to the country, and that 

 this is particularly the case with trade-winds which 

 herald the break of the rainy season, and during the 

 whole of that season bring a more or less constant 

 supply of moisture-laden clouds to drench the parched 

 country. Except near the equator, where the rainy 

 season is more regularly distributed throughout the 

 year, there are at other times of the year dry winds, 

 which have the opposite effect, for they increase 

 evaporation without bringing any adequate rain to 

 replace what is taken away. During that time, there- 

 fore, only such trees as are provided with the means 

 to resist such transpiration can survive. The most 

 common method of resisting the drying influence of 

 the air is leaf-shedding, and it is for this reason that 

 forests will be leafless during the hot weather, that is, 

 during the rainless period, and not through the winter 

 as in temperate and arctic zones, where it is the frost 

 which has. a desiccating influence. 



The mechanical effect of the wind on trees is felt 

 especially in exposed places, as on a sea-shore, where 

 the tree vegetation may often be seen to be stunted and 

 cut away slanting upwards from the water's edge, the 

 hinder ranks of trees gradually increasing in height 

 behind the shelter of those bearing the first impact of 

 the winds. Solitary trees in such localities are frequently 

 seen bent down with their crowns almost parallel with 

 the ground. On exposed mountain ridges twisted crowns 

 and the twisted fibre of the timber will constantly testify 

 to the action of the wind. As the violence of the wind is 

 much greater at some distance above the ground than 

 near the surface, tall trees are more liable to have 

 twisted fibre than short ones, or at least they will grow 



