316 



FOKE^TRY INVESTIGATIONS U. S. DEPARTMENT OF AGRICULTURE. 



SANITARY INFLUENCE. 



(1) The claimed Influence of greater purity of the air due to greater oxygen and ozone pro- 

 duction does not seem to be significant. (P. 171, Bui. 7.) 



(2) The protection against sun and wind and consequent absence of extreme conditions may 

 be considered favorable. (P. 171, Bui. 7.) 



(3) The soiL conditions of the forest are unfavorable to the production and existence of patho- 

 genic microbes, especially those of the cholera and yellow fever, and the comparative absence of 

 wind and dust, in which such microbes are carried into the air, may be considered as the principal 

 claim for the hygienic significance of the forest. (P. 172, Bui. 7.) 



We may summarize that the position of the forest as a climatic factor is still uncertain, at 

 least as to its practical and quantitative importance, but that its relation to water and soil condi- 

 tions is well established. As a climatic factor, it would appear that the forest of the plain is of 

 more importance than that of the mountains, where the more potent influence of elevation 

 obscures and reduces in significance the influence of their cover; as a regulator of water condi- 

 tions, the forest of the mountains is the important factor; and since this influence makes itself- 

 felt far distant from the location of the forest, the claim for attention of Government activity and 

 for statesmanlike policy with reference to this factor of national welfare may be considered as well 

 founded. Every civilized government must in time own or control the forest cover of the moun- 

 tains in order to secure desirable water conditions. 



In conclusion, I may urge that systematic observations bearing on the subject of forest influ- 

 ences should be instituted in this country by a Government agency, perhaps under the authority 

 of the Weather Bureau and with the cooperation of the agricultural experiment stations. Mo 

 other country is so well adapted for the study of this question as the United States, offering all 

 the varying climatic conditions of a whole continent under one government, with changes in 

 forest conditions constantly progressing. 



„ GRAPHIC ILLUSTRATIONS. 



The following diagrams, reproduced from Bulletin 7, represent more in detail, yet in a succinct 

 manner, the results of the long-extended series of observations by the Prussian forest-meteoro- 

 logical stations. These stations were double stations; i. e., one set of instruments was placed in 

 the forest and a corresponding set at some distance from the forest in open fields. The stations 

 represent varying conditions in geographical and topographical location and in character of forest 

 growth. At Lintzel there was only one station, originally in an extensive open heath, which was 

 gradually planted to forest, allowing an observation of changes due to these changed conditions. 



The conditions at the various stations were as follows: 



German stations for forest meteorology. 



Station. 



Fiifzen 



Kurwien 



Cailbboig 



Eberswalde 



Schmiedefeld 



Fiietlriehsrodo . . . 



Sonnenberg 



Mimenthal 



Lintzel 



Hadersiobon 



Schoo 



Lihnhoi 



Hollerath 



St. Johann 



Hagenau 



Neumath 



Melkerei 



Latitude 



54 30 

 5i 34 

 50 28 

 52 50 



50 3G 



51 52 



51 45 



52 16 



52 59 



55 10 



53 36 

 50 53 

 50 27 

 48 29 

 48 50 

 48 59 

 48 25 



Longi- 

 tude east 

 ot Ferro 



Ela- 

 tion. 



Kind ol tr< es and 



age at founding 



of station. 



// 



Feet. 



38 1J 



128 



39 9 



423 



34 



2,484 



31 29 



79 



28 28 



2, no 



28 14 



1, 296 



28 10 



2, 549 



28 38 



420 



27 55 



325 



27 9 



125 



25 14 



10 



25 54 



1, 998 



24 3 



2,024 



26 59 



2,493 



25 28 



499 



24 57 



1, 158 



24 57 



3,064 



45-year spruce 



80-140-year pines . 



45 year spruce 



45 ^\ear pmes 



GO-70-year spruce . 

 65-83 year beeches 



45-vear spruce 



Q0-} eai beeches . - - 



70~80-year beeches . 

 20 year pmes .. ... 

 70- \ ear beeches — 

 45-year spruces — 

 50-year spruces — 

 55-65 year pines ... 



45-year heeches 



60-80-year beeches . 



Distance to margin 

 of lorest. 



Foiest 

 station. 



Field 

 .station 



Feet. 

 262 

 679 

 591 

 410 

 984 

 367 

 328 

 984 



410 



656 

 2,461 



361 

 1,640 

 4,167 



820 

 3,937 



Feet 

 4)9 

 4 J3 



869 

 591 

 492 

 1, 1 18 

 6)0 

 636 



394 



1, 640 



640 



328 



656 



2,192 



820 



5,249 



Beginning 

 ol obser- 

 vations. 



1873, 

 1873, 

 1874, 

 1875, 

 1881, 

 1874, 

 1877, 

 1878, 

 1881, 

 1875, 

 1876, 

 1877, 

 1874, 



x, 1. 



xn, L 



XI, 1. 



\n, i. 

 x, i. 



x, i. 

 vi, J. 



V, 1. 



iii, i. 



X, 1. 



x, i. 

 vi, i. 

 x, i. 



1875, v, i. 

 1875, v, i. 

 1875, v, i. 



