518 ANNUAL REPORT OF THE Off. DoC. 



that SO far as farms are concerned, the scale cannot spread from 

 orchard to orchard, and that an infested orchard is no great men- 

 ace to the neighboring farm. In villages it is different. There the 

 scale may pass from lot to lot, though generally but slowly. 



THE FOREST IN ITS RELATION TO HORTICULTURE. 



By I. C. Williams, Deputu Commissioner nf Forestry, Hurrishurg, Pa. 



The relationship existing between forestry and horticulture may 

 or may not be near or intimate. The effect of the forest upon what 

 the horticulturist concerns himself with may not be apparent to the 

 casual observer; but such relation is no doubt real. This effort, 

 therefore, will be directed toward showing how and why it exists, 

 the benefit to be derived by one from the other, together with some 

 suggestions which it is believed would be well for the Association 

 to consider. 



One of the very important uses of the forest is the conservation 

 of moisture. A treeless region is a dry country, sometimes arid 

 and sandy. A dense forest cover shades the ground, and prevents 

 the effect of the direct action of sunlight and rapid evaporation. The 

 forest floor, if protected from fire, will soon be covered with a thick 

 mulch. The roots of the trees, penetrating deeply, form bonds to 

 knit the soil together, as well as water conductors to carry surplus 

 rain beneath the surface. The mulch receives water and holds it 

 as a sponge, pre\L'nts rajnd flow-oft", and covers the forest floor as a 

 wet blanket. In a treeless region the rains beat the soil, from the 

 top of which the water rushes, usually carrying a considerable part 

 of the soil therewith, the streams and rivers are gorged with water, 

 following which is the usual destruction of bridges and fences, 

 inundation of lowlands, and deposition of silt, gravel, and other 

 debris upon valuable meadow lands. What does not thus flow off 

 quickly evaporates, and is dispersed by the winds. Without the 

 great natural reservoir, the forest, the water is speedily gone, 

 dryness follows with its inevitable injury to vegetation. 



With the forest cover intact, a small part of the falling rain is 

 immediately returned to the air by evaporation from leaves and 

 branches, some is absorbed, a part descends trunks and following 

 the line of roots reaches deep underground strata, while the re- 

 mainder is held by the mulch and slowly allowed to sink below the 

 surface. Very little of the rainfall thus runs directly off. As a re- 

 sult of the above, springs are steadily fed, a moderately even flow 

 is maintained, no unusually high water stages are followed by un- 

 usually low stages. While the rain may descend never so hard, a 

 stream flowing from a well wooded region is seldom if ever colored 

 by the washing of soil. 



Among the functions of the leafy i)art of the forest is the ex- 

 halation of watery vapor into the atmosphere. It has been calcu- 

 lated, from experiments, that a square mile of average forest will 

 exhale three and a third millions gallons of water in a month, or 

 one hundred and ten thousand gallons a day, being two thousand 



