Periodical Literature 557 



soil in which oak does not thrive into a mixed timber forest. 

 For instance, how many pines must be introduced into the beech 

 basis, to secure the normal volume growth of a pine stand and 

 what is the reduction in the beech? 



The difficulty in this case of finding sufficiently large areas of 

 the mixture of pine and beech in sufficiently similar proportion 

 was overcome by securing data from a number of small areas, 

 too small for generalization (1/16 to 1/8 of an acre), and adding 

 them. Difficulties were also introduced by the thinness of the 

 bark of beech compared with pine (to the disadvantage of the 

 latter in measurements) ; again the question of age differences, 

 the question of what is to be considered as main and side stand, 

 of site classification raised doubts. 



In attacking this last problem, the sample plots were taken as 

 containing a certain number of pines per hectare in num- 

 ber classes, and the data of measurement, averaged for such 

 number classes, comprised besides actual stem number of the 

 two species, their basal area and average diameter, the height for 

 the two species being averaged for the whole stand, aged 62 

 years for beech, 56 years for pine, remeasured 9 years later. By 

 multiplying basal area with average diameter of the pines, it was 

 thought a value measure could be established for comparative 

 purposes, the pine increasing in value as the diameters. 



A table shows the record and a graphic illustration assists in 

 seeing the relationships, the most interesting of which is found 

 in the change of stem numbers as well as basal areas in the dif- 

 ferent stem number groups. In the groups with a small num- 

 ber, up to 400, the basal areas had increased in spite of some de- 

 crease of numbers, but in those above 500 it had decreased, i.e., 

 the loss of stems had not been made up by increment. The value 

 measure products showed that an admixture of about half the 

 normal stem number of the yield table is sufficient to attain the 

 normal yield table figures and with a larger number essentially 

 exceeds the table figures, up to 40 and 50 per cent. 



In the beech a very considerable decrease in numbers took 

 place, as well as of basal area. The following silvicultural con- 

 clusions are drawn : If a sufficiently large number of pines is 

 assured, the pine-beech mixture is desirable. This is also visible 

 in the efifect of the beech admixture in clearing the pine boles. 

 Mixtures, which in their value increment fall below a certain 



