INTRODUCTORY REMARKS. 



The sylviculturist's work does not end with the creation and 

 establishment of a forest crop; ill order that the crop in question, 

 shall fulfil in the most complete manner the object of its existence, 

 it must be constantly treated in the way that will conduce most 

 effectively to the realisation of that object. 



On page 109 we have already, summarily enumerated the 

 three distinct purposes, one of which at least every forest is called 

 upon, in the economy of man and nature, to fulfil. In the 

 immediately following pages we will confine ourselves to the case 

 of forests grown solely for the market, omitting all reference to 

 that of forests maintained for the landscape and only incidentally 

 dealing with that of forests, the role of which is to afford protec- 

 tion. 



The productiveness of a crop will obviously depend on five sets 

 of circumstances, viz., (1) the amount of protection afforded, (2) 

 the climate, (3) the soil, (4) the constituents of the crop, and (5) 

 the way in which it is made or allowed to grow up. All five sets 

 of circumstances necessarily act and react on each other, and no 

 one of them can be considered without involving a consideration 

 of, or reference to, the rest. 



In respect of protection we will concern ousrselves in this Ma- 

 nual only with the prevention and suppression of fire in forests, as 

 the other branches of the subject fall under the special heads of 

 Law, Police, Administration, Zoology and Botany. 



The influence of climate on the growth of forests has been 

 pretty fully considered in Part I at pp. 26, 53-61, 86 and 89, 

 and the extent to which climatic influences may be qualified by 

 cover is explained at p. 9. Regarding the modifying action of 

 forests on climate it is enough to say here, without devoting ;i, 

 special chapter to it, that it consists in the moderation of extremes 

 of temperature and therefore in the narrowing of the daily and 

 annual range, in the raising of the mean in cold and its lowering 

 in hot localities, in increasing and maintaining atmospheric mois- 

 ture and hence in increasing and prolonging dew-deposition and, 

 in most cases, also rainfall, in tempering winds and diminishing 

 their velocity, and, as a consequence of all this, in the prevention 

 of sudden or wide fluctuations. This modifying action of forests 

 will obviously be effective in proportion to their height, density and 

 evergreen nature. 



