118 FOREST INFLUENCES. 



The balance of waters in forest regions can not be made up until 

 there is greater certainty as to the jirecipitation over forests. 



It has already been shown tliat the forest preserves a considerable 

 proportion of the waters which reach its soil. This is due, for the 

 most part, to its lessened evaporation, and this alone would account 

 for the moisture of forest soil, for the preservation of bodies of water, 

 and of perennial springs in regions of dense forest. If the forest also 

 condenses more moisture from the air, then the same effects would fol- 

 low in regions more lightly clothed with woods. 



FOP^ESTS, WIND, AND STORMS. 



There remain a few points of more or less interest, which have 

 received considerable discussion, but have not been the object of sys- 

 tematic observation. Among these is the windbreak effect of the 

 forests. Like any other elevation above the surface, the forest pro- 

 tects from the wind objects Avhich are in its lee, and, over a very much 

 smaller area, those which are on its Avindward side. The outlines of 

 the protected area are detiued by the outlines of a snowbank before and 

 behind a fence. A section is given in the accompanying figure, where 

 A Bis the fence, T^ the snow to Aviudward of it, L that to leeward. 

 The windward protection is so small as not to deserve discussion in 

 this connection. As to the leeward protection, tlie chief point of inter- 

 est is the length of the line B as compared with the height A B, or 



adds : ' Hence one resvilt of the unsyHtematic registration of the rainfall in the Central 

 Provinces is to postpone the decision of the influence of forests on rainfall in that 

 area for another twenty years. It is only one of the many cases of the worthless- 

 ness of unsystematic observations.'" 



It is of interest also to note the following from the same source: 

 " In the following extract from the same report Mr. Eliot refers to the observations 

 recently undertaken in the forests of the Saharuupoor district. For the reader un- 

 acquainted with the Western Himalayas it is necessary to explain that a rao is a 

 water conrse issuing from the hills, and having, generally, a broad, shallow bed, 

 which cojisists mainly of bowlders and shingle, and is therefore quite dry or almost 

 dry, except after a continuous heavy shower. Mr. Eliot has not mentioned that in 

 each rao levels are accurately taken every year along one and the same line, in order 

 to note the changes that may occur in the section of the rao in consequence of the 

 fire conservancy of the entire basin above. 



"A different method has been introduced in the Saharunpoor forest division. 

 Twelve representative raos, between the Ganges and Jumna rivers, have been selected 

 for purposes of observation by the inspector-general of forests and conservator of 

 the school circle, and in each forest chowki a rain guage is suitably placed. Five 

 of them are located in the forest of Sakrauda, which is neither closed to grazing nor 

 protected from fire. The rainfall measurements will be made by the forest guards, 

 and the returns submitted to the meteorological department for critical examina- 

 tion. These observations will probably give a valuable series of data for testing 

 the effect of different forest conditions in modifying the amount of rainfall, and 

 hence also probably throw some light on the general question of the influence of 

 afforestation on rainfall." 



