CHAPTER VIII 



CONDITIONS AFFECTING THE PLANTING OF WATER 

 CATCHMENT AREAS 



In considering the advisability of afforesting a water catch- 

 ment area, the principal points to be ascertained are the 

 acreage and situation of the land that will prove suitable 

 for planting and the species that ought to be employed. 

 Before drawing up any scheme a preliminary survey of the 

 ground is necessary, careful attention being paid to the 

 different factors that influence the growth of trees. In 

 other words, the altitude, shelter from wind or exposure, 

 the nature and depth of the soil, and the existing vegetation 

 must be ascertained for each of the different sections into 

 which the area can be conveniently divided. It is very 

 seldom that the whole of a watershed can be covered with 

 trees. Plantations will not succeed at a high elevation 

 or in exposed situations, or where the ground is covered 

 with solid rock or with deep wet peat. It is generally 

 admitted that the larger the block to be planted, the more 

 economical will be the initial cost of fencing and planting, 

 and the expense of care and management in after years. 

 This argument need not be pushed to extremes in the case 

 of municipally owned land, where commercial profit is not 

 the sole consideration. On catchment areas where exten- 

 sive schemes of afforestation seem impracticable, it will be 

 advantageous to plant belts of trees or narrow plantations 

 around the reservoirs and above the streams leading into 

 them, and by this means diminish the risk of contamination 

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