FORESTRY. 1043 



The relation of the Southern Appalachian Mountains to inland water 

 navigation, M. O. Leighton and A. H. Horton (U. 8. Dept. Agr., Forest Serv. 

 Circ. t.'/S, PI). 38). — In this circular the results are given of a study made under 

 the direction of the United States Geological Survey of most of the navigable 

 rivers of the southern Appalachian region. The effect of establishing a system 

 of reservoirs and the preserviition of the forest cover upon the navigability and 

 general value of these streams is also discussed. The rivers under considera- 

 tion are divided into two general systems, those which discharge along the 

 Atlantic coast and those which discharge into the Ohio. Topograi)hic surveys 

 were made in the various river basins and selections were made of suitable 

 sites for reservoirs. The selected sites, together with the facts concerning 

 them, are presented in tabular form and in most cases further data are given 

 showing the estimated influence of these reservoirs in increasing the stage of 

 the river to various heights. 



As a result of this investigation the conclusion is reached that the proper 

 improvement of many rivers may be practically and thoi-oughly accomplished 

 only by the use of storage reservoirs and the retention of tlie forest cover. The 

 importance of preserving the forests for the prevention of flood damage, preser- 

 vation of timber resources and water i)ower is also brought out. 



The light requirement of forest trees and the methods of measuring' light, 

 E. Zf.derbauer {Separate from Centhl. Gemm. Forstw., 33 (1907), No. 8-9, pp. 

 6, fifi. /). — A description is given of the author's investigations along this line, 

 together with the methods employed in determining the quality and quantity 

 of light absorbed. 



As a result of the present investigation, which included the examination of a 

 large number of tree species, the author finds that trees exert a selective and 

 variable absorption on the sunlight. Red rays appear to be absorbed by all 

 species as well as blue and violet, while the indigo and orange rays appear to 

 be strongly absorbed by such species as the flr, spruce, and beech. Red rays 

 are absorbed to the maximum degree and gi'een to the minimum, while blue 

 and violet are absorbed to a somewhat less degree than red. 



The author is of the opinion that the method of measuring light by the use 

 of silver chlorid paper is unsatisfactory, since the paper affects only the 

 chemical rays. Reference is made to the work of numerous investigators on 

 this sul).iect. 



The forest formations of Boulder County, Colorado, R. T. Young {Bot. Gaz., 

 ..'t'l {1 901), No. ,7, pp. 321-352, figs. 12). — In this paper, in addition to a brief 

 account of methods employed and a short description of the physical features 

 of the region studied, consideration is given to the following points: Com])osi- 

 tion of the forests with reference to the controlling and most conmion secondary 

 sjtecies and the relation between them, physical character of the habitat with 

 reference to water content of the soil, tenqterature of air and soil, humidity, 

 light, i>ressure (altitude), slope, and exposure, and the past and itresent extent 

 of the forests and their i»resent movement, including deforestation and refor- 

 estation. The work here discussed is based ui)on the author's investigations 

 made in the sunnners of 1(»02 to lOO!'*, inclusive. It is hoped that it will ju-ove 

 of value in throwing light on. the determination of the physical conditions under 

 which the forests exist. 



Forestry and agriculture, F. ScirusTKR (Jahrh. Natiirir., 22 {190(i-l). pp. 

 23.'j-2o0). — Tins chajiter reviews iirogress diuMng llt('(»-7 in relation to the influ- 

 ence of forests on the ground water, moor culture, the effect (tf ai)plications of 

 straw on yield of crops, foreign forest and park trees for Europe, okra, a new 

 vegetable, potato toi)S as a feeding stutf. and the influence of previous croitping 

 on the yield of potatoes, the germination of pine seeds, the use of connnercial 



