4 PROTECTION OF WOODLANDS. 



lations, frost, heat, or the damage the crops are liable to suffer 

 from insects or weeds. And as the laying down of the principles 

 of management, the approval of the working plan, and the revision 

 of the results attained, are the duty of the head of the depart- 

 ment or of the responsible agent, it may well be said that this 

 branch of Forestry is one that concerns all the establishment, 

 and that in this sense all the establishment is classifiable as 

 protective. 



4. Headings under which the consideration of Protection of 

 Woodlands falls. 



It is convenient to classify the dangers threatening woodlands 

 into three groups, according to the nature of the causes of the 

 impending damage. Thus, we speak of dangers or damage : 



i. From inorganic causes or agencies. 



ii. From organic agencies. 



iii. From human agency or the actions of men. 



In considering these sources of danger more closely, we find that 

 the dangers or damage may be due to the following more detailed 

 causes : 



i. Inorganic agencies: 



1. Low or high temperature frost or heat. 



2. Atmospheric precipitations rain, snow, hoar-frost, ice, 



hail. 



3. Violent aerial currents wind and storms. 



4. Lightning. 



5. Unfavourable conditions of soil wetness, shifting sand. 



6. Diseases of trees, in so far as these are not occasioned 



by fungoid parasites. 



To these might also be added the destructive results of fires, so 

 far as they can be caused by lightning or the spontaneous com- 

 bustion of fermenting vegetable matter. As, however, fires arise 

 with few exceptions (through lightning) from human negligence, 

 wantonness, or malice, it appears more expedient to classify them 

 under section iiL below. 



ii. Organic agencies, comprising damage done either by plants 

 or animals. 



iii. Human agencies, or the actions of men either in regard to 

 interference with the proprietary rights, or with reference to the 

 purloining of, or damage to, forest growth. 



