4 On the Relation between Forest Lands 



least ones on open untimbered level country. For instance, 

 our greatest observed rainfall occurs at Fern-tree Gully, on the 

 south-west slope of the Danclenong Range ; next to this come 

 Berwick, and Lower Macedon ; then Daylesford, Trentham, 

 Hastings, and Birregurra, all closely-timbered localities or 

 near forest-clad ranges. Our lowest rainfall takes place 

 about Swan Hill and along the western Murray ; then 

 comes the Horsham district, and that remarkable area of 

 small rainfall surrounding Cressy, Darlington, Wickliffe, &c. 



From this it would appear that, in Victoria, at least, forest 

 lands, if high, are favourable to rain precipitation ; while 

 level, open, and sparsely-timbered country is undoubtedly 

 less fortunate in this matter. 



We now come to another part of the question — Will 

 denuding the forest lands of timber increase or lessen the 

 rainfall, or will it affect the climate, and how ? 



Our experience in Victoria does not reach far enough back 

 to answer this question decisively. We have rainfall 

 statistics of only a very few places prior to 1862, and 

 from stations generally distributed over the colony only 

 during the last ten or twelve years. These data are not 

 sufficient to show whether or not any marked change has 

 occurred. 



In a few localities, where the clearing of mountain ranges 

 has been carried on extensively, it is gathered from local 

 information that the perennial mountain streams have much 

 diminished ; but no actual diminution of rainfall has been 

 shown to have occurred. Yet, nevertheless, it may reason- 

 ably be inferred that such has been the case. While, there- 

 fore, we fail to obtain any satisfactory reply to this question 

 from precise observation or measurement, physical science 

 will furnish a trustworthy answer to a large part of it. 



It has already been remarked that forests greatly reduce 

 the extremes of temperature to which the ground would 

 otherwise be subjected, keeping it warmer by night and 

 cooler by day. Evaporation from the surface is also greatly 

 retarded, so that in forest lands the benefits of rain precipi- 

 tation are thus unusually 'enhanced, and not only for the 

 timber-clad districts themselves, but also for all areas sup- 

 plied by streams of which these form the gathering 

 grounds. 



Evaporation is always going on from the leaves of trees, 

 and this tends considerably to cool and render less dry the 



