PERIODICAL LITERATURE. 



In Charge : 



Botanical Journals R. T. Fisher 



Foreign Journals B. E. Fernow, R. Zon, F. Dunlap 



Propagandist Journals H. P. BakER 



Trade Jour7ials F. Roth and J. F. Bond 



FOREST BOTANY AND ZOOLOGY. 



Dr. Cieslar, who published an extensive 



Light study on the influence of different degrees 



Relatioyis of light on soil conditions and on volume 



production, based on entirely novel and 



scientific methods, (briefed in vol. Ill, p. 167) rehearses the 



contents of his monograph and enlarges further on the role 



which light plays in the forest, and develops in most interesting 



manner a wealth of new knowledge. 



Calling attention to the difference in composition of the soil 

 cover in an open field and in the forest and to the gradual 

 change and transformation which takes place as a young planta- 

 tion grows up and closes its crowns, and as well in opposite 

 sense when in old age the crowns thin out and the crown cover 

 is broken, he concludes that first and last this phenomenon is a 

 result of changes in light conditions directly or indirectly. 



What are the changes in the soil when the crown cover of a 

 dense forest is opened up and larger amounts of light are ad- 

 mitted to the soil ? Not only the soil cover but the substance of 

 the soil itself is changed. The first effect of a thinning is to ac- 

 celerate the humification of the foliage and litter on the ground, 

 for larger amounts of air, /. <?., oxygen, are admitted. At the 

 same time the temperature of the air and soil is raised, as proved 

 by Hoppe, favoring this humification. This investigator also 

 showed that the humidity of the .soil in the more open stand is 

 in the average greater than under the denser cover, which also 

 favors humification. Finally, however, an absorption of the 

 humus takes place and the humus contents of the soil decrease, 

 for while in the fully stocked areas the humus contents were 

 found by Hoppe to be 2.09 to 2.14 per cent., in the thinned 

 areas these figures were reduced to 1.70 to 1.74 percent, in a 



