No. 4, February, 1922] FORESTRY 251 



east coast of north Sleswick in a broad-leaf forest composed chiefly of beech. The terrain 

 was rolling and the soil a fresh, slightly sandy loam. In both areas the spruce has changed 

 the soil, through the influence of a mossy covering, especially Polijirichum, into a decided 

 hard pan in G5-70 years. This effect was most pronounced in the center of the spruce stand 

 and disappeared under the surrounding beech. According to the author it is caused by the 

 formation of raw humus under the heavy spruce cover and the leaching of the soil by humic 

 acid. The present tendency to convert poorly reproducing beech stands into spruce should 

 therefore be critically considered. — /. Roeser. 



1661. Schubert, Jon. Ertrag eines Normalwaldes. [Yield of a normal forest.] Zeitschr. 



Forst- u. Jagdw. 51: 200-265. Fig. 1-2. 1919. — The author discusses forest, soil, and total 



net yields in normal stands of Norway spruce, on the basis of yield tables by Schwappach. 



Representing the net forest revenue (r) as a function of the rotation (u), and a slight increase 



in period of rotation as Am and the corresponding change of r as Ar, the net forest revenue 



At* 

 reaches its highest value when — equals zero, which is with a rotation of 113 years. The 



author concludes that the rotation Uh yielding the greatest soil revenue is expressed by the 



formula = -^-—, where N represents the normal supply. At the following rates of interest, 



AiV 100 



1, 1.5, 2.0, 2.5, 3.0, 3.5, and 4.0 per cent, the rotation is respectively 92, 81, 74, 69, 65, 61, and 

 58 years. The total net revenue culminates in a higher rotation than the soil net revenue. — 

 The average increase in lumber prices in the Prussian state forests during the period 1833- 

 1912 approached 1.5 per cent annually. — J. Roeser. 



1662. Schwappach. Neuere Untersuchungen iiber dem Wachstumsgang der Schwar- 

 zerlen-Bestande. [Investigations of growth rate of black alder [Alnus glutinosa Gaert.] stands.] 

 Zeitschr. Forst- u. Jagdw. 51: 184-190. 1919. — A comparison of results of investigations in 

 1918 with results of a single observation in 1902 shows: (1) The total increment of black 

 alder stands is only a little higher in 1918, and the difference occurs in the period following 

 the 40th year; (2) 40-^5 per cent, instead of 30 per cent, of the total increment is removed in 

 thinning; (3) the current annual increment and the average annual increment attain a maxi- 

 mum in comparatively late years, the former at approximately 45, the latter at 70 years. In 

 general, coppice can no longer be considered suited to black alder. A normal yield table for 

 black alder is included. — /. Roeser. 



1663. Seelen, von. Der Wald als Bruder des Feldes. [The forest as brother of the farm.] 

 Zeitschr. Forst- u. Jagdw. 51: 308-315. 1919. — This article is a humorous rebuttal of forester 

 Mertens' opinion that certain forest rights-of-users (Waldgrundgerechtigkeiten) should be 

 discontinued. Mertens would place the collection of dry, fallen wood under a permit system, 

 but Seelen argues that this would result in petty trespass. The former also favors the estab- 

 lishment of permanent forest pastures in preference to the use of forests for grazing; but even 

 if only \ of Germany's cattle were grazed in such pastures, approximately 2,000,000 hectares 

 of the best forest soil would have to be set aside, which would be a great economic mistake. 

 Although the results of rights of pannage (Mastnutzung) have not been successful, this 

 practice should be given a thorough test. — /. Roeser. 



16C4. Severin, G. Un insecte nuisible au chene. [An insect injurious to oak.] Bull. 

 Soc. Centrale Forest. Belgique 23: 270-279. Fig. 1-11. 1920.— A'en«es quercus (L.) CKLL 

 or K. reniformis (Fourcr.) Sign, was found to be the insect causing damage to woods in the 

 Meuse and Sambre valley. The life history of the insect is given. A bibliography is added. — 

 W. C. Lowderviilk. 



1665. Severin, G. Un insecte nuisible au chene. [An insect injurious to oak.] Bull. 

 Soc. Centrale Forest. Belgique 23: 314-323. Fig. 12-21. 1920.— The life histories of Coc- 

 cinidae are continued and an account of Lecanium and Kertnes quercus is included. — W. C. 

 Lowderviilk. 



