270 THE FORESTS OF CANADA. 



states which are naturally adapted to the growth of timber, 

 such as New York and New England, the old forests have 

 been long since cut down, and will probably never have a 

 chance of springing up again, as these states are the 

 most thickly populated parts of the Union. Then again 

 that immense region lying between the Mississippi and the 

 Rocky Mountains is positively treeless, except along the 

 margins of a few of the streams. Two things are neces- 

 sary to the growth of forest trees, viz. a certain degree of 

 summer heat and plenty of moisture. The latter condition 

 they cannot get in the western states, where the evaporation 

 is more than double the rainfall. Given a certain degree 

 of summer heat, say from 60 to 70, with plenty of mois- 

 ture, and the most valuable timber trees will grow to per- 

 fection, and will stand almost any degree of winter cold. 

 In Canada the melting snow nourishes the roots, while the 

 hot sunshine playing on the foliage draws up the stems 

 straight and branchless to a great height. In the pine 

 forests it is not unusual to see trees 6 feet in diameter at 

 the butt, and straight as an arrow, growing to the height 

 of 100 feet without limb or fork. 



Nature's rotation of crops in the forest is an interesting 

 study. Where a deciduous forest has been cut down or 

 destroyed by fire, spruce and fir trees rapidly spring up. 

 Where a pine forest has been destroyed by fire, blue- 

 berries and raspberries grow in immense profusion for the 

 two or three subsequent seasons ; then cherry, white 

 birch, maple, and popple (American poplar) commence 

 to make their appearance, shoot up with surprising rapi- 

 dity, and soon a forest of deciduous trees occupies the site 

 of the ancient pine forests of the country, relics of which 



