Periodical Literahire 139 



years rese?its by a loss of ijicreyneiit 271 the lower shaft all priming 

 7vhich takes more than 07ie or two of the lower poorly-foliaged 

 whorls. 



The same experience was had with the Austrian Pine, and 

 the proportionahty of increment and crown density may be 

 merely due to the relatively poor development of the latter. 



The relations between light intensity and lower vegetation 

 and its influence on soil and regeneration can be discussed only 

 with reference to concrete conditions and botanical survey, 

 which determines the different species and their relative number 

 under different light conditions and soils. 



A number of tables enumerating the plants are given, in 

 which the dominant species are noted by heavy type. The gen- 

 eral law is readily visible that with the same tree species and 

 soil, the number of species in the soil flora, as well as of in- 

 dividuals grows with the greater degree of light. In one series 

 of beech areas the species numbers were 9, 15, 29, 41 ; in 

 another series 17, 25, 79. In pine areas the numbers were 10, 

 15, 14, 16, the difference being much less than in beech. 



In the beech stands no dense cover, only single individuals 

 develop in the thinned areas until the thinning goes to 65 per 

 cent, of the cross-section area, when, in a few years a dense soil 

 cover of herbs and shrubs results, and when thinned to 50 per 

 cent, a luxurious dense mat of vegetation covers the ground. In 

 these concrete conditions, therefore, from the standpoint of soil 

 preservation the removal of one-third of the full stand or more, or 

 when more than 40 per cent, of the light was admitted, becomes 

 critical. The increment per cent, appeared highest where the 

 thinning had taken but one-fifth of the cross-section area, which 

 may, however, have been only an accident. 



It should be possible to secure, at least for the principal types 

 and sites, such data regarding light intensity as maj- be utilized 

 in practical silviculture. 



The progress of gradual chatige in the soil vegetatio?i with in- 

 creasing light intensity may be traced as proceeding in the same 

 sense in which the species vary from the less-severeh' to the se- 

 verely-thinned areas. The first members of the plant society 

 under the dense shade will be the true humus plants, Neottia 

 and Monotropa ; then, as in opening up the minimum of light 

 requirement for each species is reached, it appears, and vanishes 

 when this minimum is again lost, for just as in the arborescent veg- 



