Periodical Literature. 185 



soil moisture and light supply must work together for best suc- 

 cess. 



In this connection it should not be forgotten that with decreas- 

 ing light intensity the amount of transpiration is also depressed, 

 hence with small amount of light the plant cannot utilize a full 

 supply of moisture, i. e. a smaller supply produced the same re- 

 sult as a more ample one. On the other hand an excess of light 

 supply may produce weedgrowth on the soil, which would rob 

 the surface soil in a greater degree than the roots of the mother 

 trees. 



The author then concludes, that not only a difference in light 

 requirements distinguishes the species, but a relation between 

 light supply and volume production, the tolerant species within 

 certain limits of light supply suffering less loss of increment from 

 a lack of light than the intolerant. An optimum of volume pro- 

 duction can be secured only when the two factors, light and moist- 

 ure, are at an optimum. An increase of production by providing 

 the most favorable soil moisture conditions can be secured only if 

 the light supply is above the minimum light requirement of the 

 species ; hence soil as well as crown conditions must be considered 

 in natural regeneration. 



In stands of tolerant species, since only top light and hardly 

 any side light is secured by an opening of the crown cover, this 

 must be made larger for the same light effect. 



For nursery work it should be noted that the best results are 

 attained not by shading (except where frost danger exists) but 

 by covering with moss between the rows weighted with lath. 



Licht- und Schattenholzarten Lichtgenuss und Bodenfeuchtigkeit. Cen- 

 tralblatt f. d. g. Forstwesen, January, 1909, pp. 4-22. 



A well illustrated study of the influence of 



Ecology forest use on soil conditions on the lime- 



of stone rocks of the island of Gotland, one 



Calcareous of Sweden's possessions, is of general in- 



Soils. terest. 



The whole island is a limestone forma- 

 tion, but of varying character, giving rise to three types of soil 

 and corresponding plant formations, namely, naked rocks, rocks 

 with drained diluvial soil, rocks with undrained diluvial soil. 

 On the naked rocks a decidedly calcophil flora of xerophilous 



