THE INFLUENXE OF THINNING 31 



opment of the fruiting bodies, and the result is a crop of small, inferior 

 sporophores, which in most cases die out in the course of from i to 4 

 years. 



Similar observations on the amount and state of injuries were made 

 for grand fir as for hemlock. In the case of grand fir much root ex- 

 posure was recorded and a large amount of injuries, including many 

 broken tops, was observed. Several of the broken tops were caused by 

 the weight of an enormous cone production, which was in progress at 

 the time the field data were taken (1915). Many of the tree-tops were 

 bent over with the additional weight, and the addition of moisture or 

 the force of the wind was in many instances sufficient to break the stem. 



the; vaeue of thinning as affecting echinodontium tinctorium 



IN western hemlock and GRAND FIR 



It is deemed unnecessary here to enter into a lengthy discussion of 

 the effects produced by thinning, from a forester's point of view. The 

 process of thinning has long been practiced in foreign forestry opera- 

 tions and enters vitally into the forestry policies of this country, where 

 it is better known as one of the systems of forest management under 

 the name of selection cuttings. Some of the recent literature dealing 

 in part directly with the influence and effect of thinning is interesting. 

 Mason," in a discussion of the light requirements of lodgepole pine, 

 gives some interesting points in connection with thinning. A release 

 from a suppressed condition by means of thinning was found to result 

 in a very marked increase in growth, amounting in one example cited 

 to an increased growth of 772 per cent in the last 12 years of growth 

 over the preceding 12 years. Tables are also included in the work, 

 showing the marked increase in the periodical annual diameter growth 

 due to the influence of thinning. 



]\Iattoon*^ gives some very interesting and striking examples of the 

 effects of thinning caused by three different agencies — ice storms, tor- 

 nado, and by logging operations. All three agencies resulted in thin- 

 ning the stand, and the stimulation in growth was very marked, the 

 trees formerly suppressed growing relatively much faster. 



]\Iore recently Roth,'^ working with firs and birches, traces the effects 

 produced in the year rings by the influence of three intermittent thin- 



" j\Iason. D. T. : The Life Histon- of Lodgepole Pine in the Rocky Mountains. 

 1915. U. S. Dept. Agr. Bui. No. 154. pp. 1-35. 



*M,attoon, W. R. : Life History of Shortleaf Pine. 1915. L'^. S. Dept. Agr. 

 Bui. No. 244, pp. 32-34- 



' Roth. Julius : Beitriige zur Lichtungsfrage. Iti Forstwissenschaftliches Cen- 

 tralblatt. Jan., 1916, pp. 43-48. 



