Forests and Climate* 



The influence of forests upon climate has been extensively 

 discussed, but it cannot be said that definite conclusions have 

 been reached. It appears to be true that aridity has resulted in 

 some cases from cutting off the forests, but that this is not a 

 necessary result appears to be proven from experience in Eng- 

 land and Spain. The former has only about 3 per cent, of its 

 area in forests, yet it continues to be proverbially fertile, and a 

 land of abundant moisture and luxuriant vegetation. Spain 

 also retains its moisture and fertility in spite of deforestation. 



Perhaps it is safe to conclude that where other strong influ- 

 encing conditions are absent, the effect of forests may be appreci- 

 able. Thus it has been pointed out that the lower temperature, 

 which sometimes prevails over a forest, may cause greater con- 

 densation and consequently increased precipitation. It seems, 

 however, that this difference of temperature does not usually 

 exceed two or three degrees, and consequently would be 

 equaled in effect by a ridge about 600 feet in height, so that 

 where the topographic relief is bold enough its influence may 

 entirely subordinate any effect of forests upon the rain-fall or 

 temperature. In like manner the influence of the sea upon 

 temperature and rain-fall may be so controlling that the effect 

 of forests becomes of little account. This is true in England, 

 and it appears to be also the case in this State. 



It may be accepted as a fact that the temperature immediately 

 over a forest is sometimes a few degrees cooler than over the open 

 country. It is no doubt true that the temperature beneath the 

 trees is materially less and the humidity somewhat greater. 



To determine what the effect of forests 'may -be in our own 

 State, we have compiled the accompanying charts N of rain-fall 

 and temperature from the records of New Jersey Statue Weather 

 Service, and from all other data accessible. In making up these 

 charts all short-period stations have had their record referred to. 



