384 Forestry Quarterly 



in addition the great variation in root formation and the very 

 variable root activity is considered, these findings may be a con- 

 tribution to the scientific justification of the mixed forest." The 

 long period of vegetation for our forest trees, middle of May to 

 middle of September, is a principal reason for their frugality. 



The method of analysis is described and the detail results on 

 alder and elm laid down in many tables. 



Here, as in other plants, four more or less definitely distinguish- 

 able periods may be observed, namely : 



1. The period from rest in the spring until the partial forma- 

 tion of new organs, during which reserve materials are exten- 

 sively withdrawn from root, stem and needles. Respiration also 

 causes loss of organic substance ; 



2. The period of lengthening and development of new organs 

 under increasing assimilation and absorption of nutrients; 



3. The principal period of vegetation, when absorption and as- 

 similation culminate ; 



4. The time until the end of vegetation with a gradual de- 

 crease of the two processes, the broadleaf trees and larch, con- 

 trary to evergreens, showing a tendency to store nitrogen and 

 phosphoric acid. 



A distinction between nutrient requirement and fertilizer re- 

 (|uirement, made by Wagner, namely, the requirement on the con- 

 dition from the soil and the amounts of nutrients found by 

 analysis in the plant, is as yet not possible. 



Zur Ausnutzung des chemischen Standsortfaktors durch Waldpflanzen. Forst- 

 wissenschaftliches Centralblatt, November, December, 1914, pp. 549-578, 

 610-621. 



As a result of measurements at 13 

 Forest double stations for 20 years, the data of 



Influence which are tabulated. Dr. Schubert states 



on that in the early winter the snow cover in 



Snoiv the forest is lighter than in the open or 



of the same depth, while in the spring the 

 forest preserves usually a deeper cover. In coniferous woods 

 the snow cover is even in midwinter lighter than in the open, 

 but in the spring it somewhat impedes the melting and evapora- 

 tion, and is relatively deeper. In spruce forest the decrease of the 



