Periodical Literature. 461 



cover and to secure the clearing of the dominant, the living inter- 

 mediate or underwood is left undisturbed. The opening up of the 

 upper crown level must be gradual; rapidity and time of return 

 depends on soil, age, condition of stand ; in younger stands not 

 less than in five year periods. 



To secure clean boles the opening up should not begin until 

 thirty or forty to fifty feet of clear bole have been secured by 

 dense position which may be in fifty to seventy-five years. Prun- 

 ing to secure this is a doubtful measure, but pruning in the inter- 

 mediate to help the development of a superior tree, when its re- 

 moval would open up too much, is commended. 



Form development and correction of composition form the con- 

 cern in the young period, until the superiority of the select is 

 readily visible and the elite can then be favored. The general rule 

 then is to take out stems which interfere with the crown devel- 

 opment of a more valuable neighbor. In a mixture of oak and 

 beech in Bramwald an average distance of twenty-five feet for 

 the elite, say sixty to eighty trees to the acre, providing for losses, 

 appeared a desirable number. These are marked with a white 

 mark on two sides, this mainly to help the eye and train the per- 

 sonnel in this new way of marking for thinning. 



Die Hochdurchforstung im Laubwalde. Forstwissenschaftliches Cen- 

 tralblatt. September-October, 1909. Pp. 461-474. 



In an article of over 100 pages, Dr. Heck 

 Results publishes the results of fourteen years' prac- 



of tice with this new method of thinning, 



Thinning called by him Freie Durchforstung (free 



in the thinning) to denote that it is independent of 



Dominant. any schematic prescriptions or rules. The 



results are given in a long series of tabula- 

 tions, in which all growth conditions are given in detail measure- 

 ments from year to year. Side by side, in the same stand of beech, 

 thinnings after the old and the new method were made and com- 

 pared in every detail. The article discusses at length every phase 

 of the subject. Of the conclusions the following may be of more 

 general interest. Stem classes, made after Kraft's classification, 

 change soon after they are made ; only one-half to two-thirds of 

 the trees remain in the same class for a decade, the rest, with the 

 exception of a few which advance, falls into a lower class. After 



