FoHKsruv. 45 



^'ardons. water S''i"(iens. rock gardens, etc., are described and the kinds of wild 

 flowers used in planting them noted. Tables are given showing the connnon 

 name, season of bloom, color, etc., of a large number of annuals iind peremiials 

 which may be used in making wild-Hower gardens. 



FORESTRY. 



Exotic forest and park trees for Europe, II. Mayr ( FrriiidJiiiKlisclic Wald- 

 1111(1 I'arkhiiiinic fiir Ihtroim. Berlin: Paul I'urcij, IDlUu pi). \ III + li.Li. jtJx. 20, 

 /ifl-'i. 2'>S). — The trees described in this work are those grown i)rimarily in North 

 Amcrici. n(ii-llicrn .Mexico. .Iiipaii. Korea, ,Sii)eria, and noi'thern ("liina. For- 

 estry conditions in these countries are described, based upon the author's per- 

 senal otiservations, and the forest zones in the different countines outlined and 

 compared with those of Europe. The cultural recjuirements and the uses of the 

 various exotic trees dealt with are given with an account of their botany and 

 correct nomenclatiu'e. General rules fen- the culture of exotic trees in Europe 

 .•ire given with plans for their culture in i)arks and fore.sts. 



Principles involved in determining forest types, R. Zon {Proc. Soc. Amcr. 

 Porcslcrs. I (I'.iiiii). \(). .i, 1)1). nn-isii). — This is a general paper on the subject 

 in which it is held that a study of the life habits of forest trees and the estab- 

 lishment of forest tyi)es nmst go h;ind in hand. Yield and volume tables should 

 lie made separate for each type. If sylviculture is to be placed on a safe basis 

 each forest should be divided into permanent, natural forest types, or types of 

 s'tuation with forest growth corresponding to them in a manner similar to that 

 of mapping soil types. It is held that when the laws of development and growth 

 have been established for a forest ^)e it will hold good for the same forest 

 type everywhere, thus giving to sylvicultural deductions the character of 

 scientitic truths of a wide application. 



The role of light in forests, A. Giesler (Cciitbl. Qusam. Forstir., 32 {1906), 

 A'o.s. 2. pi>. Ji'.)-l.i: 3, PI). U1-J22. d(jins. .)). — Results and many of the details are 

 given of extensive investigations to deteruune the effect of light on the crown 

 and stem develojiment of forest trees thinned to different degrees, and the cor- 

 responding tloral devel()[)ment of the forest floor. 



It appears that the crowns even of strongly lighted forests hold back a large 

 portion of the chemical light ra.vs. lu the case of Austrian black pine this was 

 found to be (*>0 j)er cent, tir forest SO ])er cent, and i"ed beech 90 per cent. The 

 luunerous small trees ef lightly thinned forests do not retain propoi'tionally as 

 many of tlie chemical light rays as less numerous but more thickl.v leaved 

 crowns of tile larger trees found in more heavily thinned forests. Moderately 

 thinned and heavily thinned forest trees contain practically two and four 

 times as extensive a leaf area respectivel.v as thinly forested trees. 



A linnt was found in the case of red beech, over which the mass production 

 was no longer ])roi>:irtional with the increase in crown growth. I'hotometric 

 studies with this tree favor thinning in the dominant condition, but not in the 

 dominated. 



When onl.v 40 jier cent of the chemical light rays reach the soil, the flora 

 develops to such an extent as to hinder natural regeneration. In thickly 

 closed stands of light-dein.inding trees the abundance, vigor, and number of 

 species of plants on the forest floor were incomparably smaller than in a stand 

 of tolerant trees, a fact of importance in the natural regen(>ration of such 

 woods. I'erenni.-ils made \\\\ SO to !»('. per cent of the flora species of forest 

 tloors. 



Practical suggestions for the Massachusetts tree lalanter, R. ('. IIawley 



