558 Forestry Quarterly 



measure, are to be replaced, because they cannot utilize the site 

 sufficiently. 



It is evident that the yield tables for pure stands have no 

 application in mixed stands, since the combination works differ- 

 ently from the single components. 



Another inquiry had reference to a spruce-fir-beech mixture to 

 answer the questions : How does the mixture influence volume 

 and quality? How much coniferous wood is necessary to obviate 

 the loss of increment and value of the beech? 



While interesting, this part is not so pertinent as the second 

 part, in which he gives specific directions how to proceed with the 

 mensuration of mixed stands. This part is full of suggestions for 

 men engaged in forest investigation and, if space allowed, might 

 well be translated in full. Only the salient points, however, can 

 be given here. 



Wappes feels that, in order to get real data on mixed stands, 

 everybody must help. It will not do to leave it to the experiment 

 stations, since the task is too large and the need for the data too 

 pressing. He favors the establishment of a great number of 

 permanent sample plots. 



Determination of the age of mixed stands is difficult, espe- 

 cially as they are usually uneven-aged as well as mixed. Usually, 

 it is not necessary to determine a formal stand-age, the age of 

 the chief species may suffice, but even this may be difficult. The 

 felling of mean sample trees is not always feasible. It would 

 be desirable to have an increment borer which would reach to 

 the center of trees 30-40 cm (12-16 inches) in diameter. 



Comparisons of the yield of mixed stands with the yield of 

 pure stands should be based on local measurements of sample 

 plots, not on the yield of pure stands as given in yield tables. 

 The sample plots are to be made permanent. Ordinary calipers 

 are to be used. If possible, the trees are to be numbered ; the 

 point of calipering must be marked. 



Determination of the increment is especially difficult in uneven- 

 aged, mixed stands. The use of an increment borer and Press- 

 or's formula is suggested. Complete stem analyses are cumber- 

 some for getting the volume now and X years ago, and so deter- 

 mining the increment. The best way, Wappes says, is by repeated 

 measurements of the same sample plot (see Forestry Quar- 

 terly, Vol. XIII, pp. 60-63). 



