FORESTRY. 131 



With the so called shaded seed-bed the remaining trees are allowed to 

 touch each other with the extremities of their branches or they may be 

 separated from three to nine feet or even more, according to the soil, situ- 

 ation, climate or variety. 



In the course of a few years the plants will have grown so much that 

 they will need more light which is essential to their growth; thinning out 

 is not done all at once, but at different periods and with regard to the 

 development of the growth of young wood. The thinning is generally done 

 in winter during deep snows and mild weather, as it thus protects the 

 plants better; in thinning the last wood is removed after the plant has 

 become strong enough to dispense with protection. 



The time of cultivation varies from 10 to 20 years, according to circum- 

 stances. 



All thinning out which is undertaken at the different times should be, 

 as already mentioned, in winter with deep snows and mild weather. The 

 wide spreading limbs should first have their large limbs removed and the 

 ground should also be cleared of all branches, leaves, etc. 



The trees should be felled in the direction in which they would do the 

 least harm and several trees should never be felled in the same direction 

 so as to fall upon each other. 



The further care which the forest should yet receive is the warding off 

 of harm, as Are, grazing of cattle and insects. 



Through fire the greatest destruction has taken place; millions of acres 

 of the best pine forests have been ruined by this element. Our greatest 

 attention should therefore be directed to prevent this as much as possi- 

 ble, and should a forest Are break out we should try with all our power to 

 master it, before its dimensions become too great. 



The cause of forest fires is generally the negligence or malignancy of 

 man, seldom lightning; the loss caused is more or less, according to the 

 growth of the trees and the intensity of the fire. The fire may also do 

 great damage in the clearings by heatingthe surface soil to so great an 

 extent as to burn the humus therein contained. As long as it remains 

 here it is called undergrowth ;fire, also if it attacks the wood growth; 

 here it may run along the foot of the trunks and burn the attached 

 moss and lichens; by great intensity alsothe bark — and if the last is not 

 well protected by a very thick bark against the effects of the heat the 

 burnt part will die off, and if very large the whole tree will sicken and 

 may eventually die. Generally the greatest loss is on the windward side 

 and affects the larger trunks less. The tall, young, slender trees and the 

 younger growth are generally hurt so much as to kill them. In younger 

 plantings in which some of the branches of the trees reach to the ground 

 the heat of the undergrowth Are first dries the needles and then immedi- 

 ately sets them on fire, which spreads to the rest of the planting and is 

 then called a ''forest fire" and if the intensity is great and the woods 

 thick it not only devours the leaves but also the branches and trunks. 



The danger of a fire differs greatly, according to the time of the year, 

 the growth, the thickness of the forest and the variety of timber. 



The most dangerous time is the dry time in spring and late summer, 

 while after long rains and in winter hardly any danger is to be feared. 



Where the ground is covered with dry grass, moss, etc., the danger is 

 very great, especially on south slopes and hot sands. 



