THINNING. 



117 



lower brandies too far. To counteract tins tendency, 

 and to throw the strength of the tree into the main stem, 

 the terminal bnd or shoot of the lower branches is to be 

 pinched off. Cedars and other spreading firs, treated in 

 this way, may be made to assume an upright form. 



Thinning. — ^Thinrdng is an operation nearly as neces- 

 sary as pruning, and in fir plantations perhaps the more 

 necessary of the two. As young woods are generally 

 planted more densely than is needful for their permanent 

 condition, in order that the young trees may produce a 

 shelter for each other, and a corresponding warmth in 

 the climate, the period selected for thinning the young 

 plantations should vary with the progress of the trees, 

 as that again will vary with the soil and climate in 

 which they grow. Some plantations may receive a par- 

 tial thinning by the time they have been seven or eight 

 years planted ; others in more exposed places may not 

 require the same sort of thinning till they are double 

 that age. 



In the process of thinmng it should be distinctly kept 

 in mind that the trees which are removed were originally 

 planted to shelter and draw up the trees which are to 

 remain, and that only those are to be cleared away from 

 time to time which are doing injmy to those designed 

 to be permanent. ^\Tien this principle is made to regu- 

 late the work, there is little danger that thinning will be 

 carried to an injurious excess. Nothing is more preju- 

 dicial than excessive thinmng. The bark of those trees 

 which have been well sheltered by close planting is less 

 dense and more sensitive to cold than that of trees ex- 

 posed to all weathers, and their roots are much fewer 

 and have a slighter hold of the ground. It is evident, 

 therefore, that the trees left standing in over-thinned 



