OUR FORESTRY-PROBLEM. 229 



moister air is found within and above the forest, which is communi- 

 cated to the surroundings, and tends to bring to condensation any- 

 passing clouds, which the hot air ascending from the open field would 

 have prevented. In this manner the forest acts exactly like a large 

 sheet of water, as a starting-point of local winds, by which the char- 

 acteristic features of the forest climate — i. e., shorter range of ther- 

 mometrical extremes, and greater humidity — are communicated to the 

 surroundings. Yet, whether under all circumstances, a direct increase 

 of precipitation over surrounding areas may be produced through for- 

 est influence remains still unproved, and appreciable effects can only 

 be expected from dense and extensive forest areas. 



The influence of a mechanical barrier against chilling northern and 

 hot southern blasts, such as even a simple wind-break of two or three 

 rows of trees can produce, is well known to the pi-airie settler. But 

 by far the most important function of the forest lies in the preserva- 

 tion of soil-humidity and in the storage and equable distribution of 

 the water capital of the earth. The moss and leaf-mold act as a 

 sponge, taking up all the atmospheric water which reaches them, and 

 only gradually give up the same to the soil, from which it reappears as 

 springs, brooks, and rivulets, forming the great water reservoir of agri- 

 cultural lands, giving up its accumulations gradually throughout the 

 season when most needed. While this beneficial action is especially 

 noticeable in the mountainous regions, the forest of the plains acts 

 also as a regulator of hydrologic conditions, as is apparent from the 

 observation that on deforested areas the ground-water level sinks and 

 aridity increases. While the large floods are probably, to a great ex- 

 tent, due to cosmic causes, yet it can not be denied that the deforesta- 

 tions at head-waters of streams must have aggravated the evil, and 

 that local floods and their concomitants, namely, washing away of soil, 

 pauperizing fertile valleys, etc., can be obviated by proper forestry, 

 has been practically demonstrated by the reforestation in France and 

 the Tyrol. On the paramount importance of the proper utilization of 

 the water capital of the world, a volume might be written. Suffice it 

 to say, that our agricultural development, and with it our civilization, 

 depends upon it. 



Lastly, I should recite the sanitary effects of the forest, the investi- 

 gation of which has, of late, brought many important and interesting 

 results. That the activity of individual trees in assimilating carbonic 

 acid and exhaling oxygen improves the air we breathe has been long 

 a recognized fact, and the healthfulness of forest air is therefore gen- 

 erally conceded. It is asserted that, by deforestation, malarial dis- 

 tricts have been created, while, on the other hand, the planting of 

 eucalyptus and other trees is said to have produced the opposite effect. 

 It is quite possible that the manifold ramifications of the crowns of the 

 forest act as a kind of filter in purifying the air of the spores of fungi 

 and bacteria, thus diminishing the danger of epidemics, etc. 



