28 BULLETIN 139, U. S. DEPARTMENT OF AGRICULTURE. 



the stand. After that, they should be repeated every 7 or 10 years. 

 In practice, however, this can rarely be carried out, because of the 

 present lack of market for small saplings and the prohibitive cost of 

 logging scattered trees. Thinnings in young pine stands should not 

 be heavy or the height growth will be impaired. The trees will not 

 prune so well, and the soil will not be sufficiently shaded toward the 

 end of the rotation to prevent weeds from getting a foothold and 

 endangering reproduction. Heavy thinnings, moreover, are likely 

 to result in windfall, as was well illustrated in the case of the thinned 

 stand of Norway and white pine on the Grand Marais Lighthouse 

 Reservation a few years ago. The winds off Lake Superior are very 

 heavy at times. Many of the trees left standing on the lighthouse 

 reservation lean badly and appear to have their roots loosened. In 

 this case the thinning was probably deferred too long and then made 

 too heavy. 



IMPROVEMENT CUTTINGS. 



In mature and overmature stands where, as in the case of parks, 

 the aim is not so much to secure young growth as to maintain the 

 present stand, loss would be avoided if systematic improvement 

 cuttings are made at intervals of from 15 to 25 years. The Norway 

 pine trees removed should be those with straggling and light-green 

 foliage, stag-headed, or clearly so overmature that they will not 

 survive until the next cutting. It would be better even to cut a 

 few healthy trees in clumps, in order to increase the amount to be 

 logged per acre, than not to cut at all. When an overmature forest 

 is cut systematically, it is possible to clear up the occasional wind- 

 falls, which are bound to occur in old age. 



MANNER OF CUTTING. 



In any partial cut of the stand the trees to be removed should 

 be marked beforehand, in order to insure that the thinning will be 

 carried out as planned. The method usually followed is to blaze or 

 stamp the roots and bole of the trees to be cut. Close utilization 

 of the material marked is even more important. The owner should 

 see to it that stumps are cut low (from 12 to 16 inches, depending 

 on the size of the timber), the tops utilized to the full merchantable 

 limit (in the Lake States usually 6 inches), and that logs partially 

 defective are removed, even if they contain only from 20 to 25 per 

 cent of merchantable material. It is, of course, necessary to use 

 great care not to damage reproduction which is to form the second 

 crop. Roads, skidding trails, skidways, and the cutting of seed 

 trees should be designed with this in view. 



