7;:2 JOURNAL OF FORESTRY 



quality of site may be of importance chiefly because the total perimeter 

 per acre is greater on the better sites. 



Miinch estimates that the average merchantable pine has a d. b. h. 

 of 40 cm. (circumference, 126 cm.), and that two-thirds of the cir- 

 cumference (84 cm.) can be worked. The average season lasts 4 

 months, or 122 days, making possible 60 "turns" at two-day intervals. 

 At I gram per centimeter per "turn," the yield would be 5.0 kg. per 

 tree per season, and with only 40 "turns" it would be 3.4 kgs. On the 

 best sites the trees average 50 cm. d. b. h., which according to a similar 

 computation should yield, with from 30 to 60 "turns" per year, 3 to 6 

 kilograms of resin. The average hectare with 250 trees should then 

 yield between 750 and 1,500 kilograms of resin per season. 



Furthermore, the average production of wood in merchantable pine 

 stands is 4 cubic meters per hectare, which represents a dry weight of 

 about 1,600 kg. To produce 1.500 kg. of resin would probably prevent 

 any growth of wood. It is likely, then, that from 3 to 4 kg. of resin 

 per tree is about all that can be obtained without bleeding the timber to 

 death. This yield is considerably less than that of maritime pine in 

 Germany, which occasionally reaches 3 to 4 grams per centimeter per 

 "turn." 



The great variation in yields actually obtained in Germany is stated 

 to be due rather to the method used than to the productivity of the 

 trees. Scarcity of labor prevented cutting at two-day intervals, and 

 because of the abundance of large trees the tendency was to cut many 

 lightly rather than a few up to their capacity. The season was too 

 short for the "adze" method, with little yield before July; with the 

 "groove" method, cutting downward from the original wound early in 

 the season and upward later on, there was a good flow early in May. 

 The flask and boring method of Wislicenus also yields an early flow. 



It is stated that by the "groove" method an unskilled worker can 

 easily make 470 meters of cut per ten-hour day (with an average yield 

 of 47 kg.) as compared with the best records of 144 meters for skilled 

 workers with the adze. 



He concludes that operators neither in Germany nor in Austria, 

 whence the adze method was introduced to Germany, have ever gotten 

 as large yields of resin as they might. They must both increase the 

 number and breadth of the cuts and utilize the groove (or "streak") 

 method, introduced from America, with the modification that the cut- 

 ting should proceed downward during the early part of the season. 



Dr. Kienitz notes that Scotch pine yields less resin than black (Aus- 

 trian), maritime, longleaf, or several other pines, while its wood is 



