PREVALENT WINDS. 529 



Corsican variety of Pinus Laricio, the cluster or maritime pine, 

 and of broadleaved species, sycamore, Norway maple and white 

 poplar are very resistant. Oak suffers somewhat from saline 

 spray, beech still more, and the spruce most of all. 



(b) Age of Trees. Seedlings and little plants, especially in 

 sowings and plantations, and young coppice-shoots suffer 

 most severely from cutting winds, until the ground is com- 

 pletely covered by their interlacing branches. Coppice suffers 

 more than high forest, especially when the rotation is short, 

 and high forest suffers the less, the closer is the leaf-canopy. 



(c) Locality. The most exposed localities are coast forests, 

 cultivated plains with hedgerow trees, ridges and tops of 

 mountains and hills, valleys running east and west, easterly 

 aspects unprotected by higher hills, unsheltered plateaux, etc. 



The amount of soil-desiccation by wind varies with the 

 nature of the soil and wind. The faster the wind blows, the 

 more moisture is removed from the soil. The damper the 

 soil, the more water it loses, but deep soils suffer much less 

 than shallow soils. Soil covered with low vegetation loses 

 the most water, that covered with dead leaves and humus 

 least. Bare soil is intermediate. Dry winds, under other- 

 wise similar conditions, remove more water than moist winds, 

 and warm winds more than cold winds. Wind also reduces 

 the quantity of carbon dioxide in the air contained in the soil, 

 and reduces the soil-temperature, the greater the velocity of 

 the wind, and the greater the angle at which it meets the 

 surface of the ground. Late spring and early summer are 

 the most dangerous seasons. 



2. Protective Rules. 



The chief rules consist in the maintenance of a good leaf- 

 canopy, especially in localities exposed to prevailing winds. 

 Along sea-coasts, therefore, and in high mountainous regions 

 and other exposed places, natural regeneration, selection 

 fellings and the formation of protective belts are advisable. 



Wherever clear-cuttings are preferable, after a consideration 

 of all local conditions, the following special rules should also 

 be observed : 



(a) After leaving a protective belt as far as the destructive 



F.P. M M 



