628 president's address. 



The experience of increased rainfall over the station at Lintzel 

 with increase of forest area points strongly towards interdepen- 

 dence. 



Secondly, as to the influence of forests upon the climate of the 

 surrounding country. 



Any effects that arise must either take place by diffusion or by 

 means of local air currents, or from the fact of the forest acting 

 as a windbreak. 



Deforestation allows of the uninterrupted sweep of winds over 

 the country, the evaporating and parching effects being much 

 more intense than those resulting from mere dryness of the air. 

 This class of effect is, of course, worse in flat country and on the 

 seashore. 



When moisture-laden winds pass over cool areas of forest the 

 possibility of condensation is at least not reduced, whereas heated 

 plains certainly do reduce it. The presence of large forests in 

 Asiatic and European Russia has been shown to produce a 

 sensible effect in lowering temperature. 



In general we may expect that an alternation of large forested 

 and unforested areas in regions which on account of their 

 geographical situation have a dry and rigorous climate is more 

 beneficial than large uninterrupted forest areas which would fail 

 to set up that local circulation which is brought about by differ- 

 ence of temperature and permits an exchange of the forest climate 

 to the neighbourhood. 



The results of systematic observations in forest meteorology 

 made in France, Germany, Sweden, Austria and elsewhere, and 

 extensive observations on temperature and rainfall extending to 

 Russia and India are given in the Report. 



It seems scarcely necessary to mention the sanitary effect of 

 forests. As is well known, trees have been planted with success 

 to absorb the moisture of swamps, and the exhalations of eucalypt 

 trees are particularly beneficial in counteracting malaria. 



The idea that our forests may get exhausted is often jeered at, 

 and figures have been brought forward to show what an enormous 

 and practically inexhaustible supply of timber exists; yet in other 



