462 EEAKINO OF IHK ESTABLISHED CROP. 



■will be worked out and regenerated first, so that the nurse crop 

 will always be ready when the times comes for exploiting the de- 

 licate species. Other measures for preventing frost or minimising 

 its effects are draining and piercing the forest with properly 

 directed cleared lines, which create a continuous draught and 

 thereby prevent cold air from collecting and standing in the 

 hollows. 



Excessive insolation. — Excessive insolation injures, firstly, by 

 drying up the soil, and next, by causing over-transpiration or even 

 stopping all vital processes. The first danger is prevented by main- 

 taining a sufficient number of parent or nurse trees until the com- 

 ponent individuals of the young crop have so nearly met crowns 

 everywhere and closed over the ground as to shade the soil effect- 

 ively. The same measure will also prevent the second and third 

 dangers, but in extreme cases it may be advisable not to remove all 

 the nurses until the young crop has reached the sapling stage and 

 has quite closed over the ground. In any case the degree and du- 

 ration of the protection required here ife much less than in the case 

 <if frost. 



Winds. — We have several times before this seen that extreme 

 temperatures hurt most when air is in motion and that the injuri- 

 ous effect of hot or cold or dry winds is in proportion to their 

 velocity. Hence when dangerous winds prevail, as they do in most 

 parts oi India, the only practical way of diminishing their harm- 

 fulness to young forest growth covering a large area is to check 

 their velocity-. This may be done either by interposing a screen 

 of trees, or by means of trees sprinkled all over the area, as in 

 stored coppice and in regeneration by seed under cover. In the 

 former case, the screen has to bear the full briint of the wind and 

 must, therefore, be broad, tall and dense enough,-and be composed, 

 if possible, of trees that are in leaf all the year round or at least 

 during the season when shelter is required. In regeneration under 

 cover, a sufficiently wide belt of the original crop on the wind- 

 struck edge should be preserved in the condition of an after-felhng 

 until the young crop behind is able to take care of itself ; and if it 

 is not full enough, the young growth under it should be supple- 

 mented and filled up with large transplants of some fast-growing 

 hardy species. In th« reboisement of large blanks the necessary 

 screen should be raised in advance. In every -case, the annual 

 coupes should march against the wind and be as narrow as practi- 

 cable. On hillsides a permanent fringe of forest, worked as con- 

 servatively as possible by jardinage, should be maintained along 



