WOODLOTi FORESTRY. 21 



much sunlight causes a rapid disintegration of the litter and 

 often fosters a weed growth that makes a heavy draft upon 

 the soil moisture. Fire destroys the litter, which by decay passes 

 into humus, and impoverishes the soil. 



Moisture. — The amount of moisture required by the different 

 forest trees varies greatly, and, though most trees will live in 

 any except the extremes of dryness and wet, a knowledge of 

 the preferences or requirements of each will aid one in deter- 

 mining whether or not a given tree is in a congenial situation. 

 Black spruce and larch are at home in wet swamps; rock oak 

 on stony hills ; white oak, black oak and walnut on well drained 

 lower slopes and lowlands. In nature, if a tree germinates out 

 of its range, it dies and no one is concerned about it. In forestry, 

 however, it is important to know how much moisture a given 

 tree needs in order that mistakes may be avoided. 



Litter and Undergrowth. — The litter and undergrowth protect 

 the humus and gradually add to it. They form a light covering 

 for the soil and help to maintain a condition of moisture con- 

 ducing to the decomposition of dead vegetation. They also 

 form a shelter for game. The litter and undergrowth are as much 

 parts of the forest as the trees themselves, and as such should 

 never be destroyed either by fire or by cutting. 



THEORY OF THINNINGS. 



The object of thinning a forest is to reduce the wasteful com- 

 petition by which nature 'brings the trees to maturity. While 

 they are small, many trees can find sustenance on a given area; 

 as they grow older, and each requires more room, the number 

 must be diminished. From the standpoint of the forest, a thin- 

 ning should be made whenever the individual trees begin to crowd 

 one another. From the standpoint of the owner, thinning must 

 be deferred until the trees are large enough at least to return the 

 cost of their removal. As a matter of fact, very few of our 

 forests seriously need thinning before they are twenty years of 

 age, a time at which, if advantageously located, they will usually 



