EFFECTS OF FORESTS UPON CLIMATE. 301 



It is remarked that the box-elder {l>[egundo aceroides) does not injure 

 grass and grain by its shade as much as many other species. 



The alder is thought to favor rather than injure the growth of grass. 

 The wide-spreading butternut is injurious to both grain and grass to a 

 degree beyond that of most other trees. 



It has been remarked that the autumnal beauties of the landscape in a 

 wet season, come on rapidly and soon pass away, the leaves being 

 loosened on the first shower. But in a dry season the coloring is richer 

 and the spectacle more lasting. The splendid hues of the autumnal foliage 

 appear to better advantage upon the hills than in the valleys, probably 

 because the location is drier and the adhesion of the leaves to the tree 

 somewhat greater. It is a well-known fact the American forests present 

 a brilliancy of coloring unknown in Europe, and the fact is equally well 

 established that our climate is much drier. In this wo may find the 

 reason for the difference above noticed, and from the same analogy we 

 should expect one landscape to differ from another in the same season, 

 -where the soils were different as regards moisture and dryness. This 

 change of color is not due to frost, as some suppose, but to the ripening 

 of the leaves, which will fall in their due time whether touched with 

 frost or not. 



FOKEIGN EXAMPLES OF THE EFFECTS OF FOREST UPON CLIMATE. 



I. — Climate of the Madeira Islands — illustration of tJie effect of trees uj^on 

 the rainfall. 



These islands, in common with other groups lying in the Atlantic west- 

 ward from Europe and Africa, have been cited as showing the depend- 

 ance of rain-fall upon forests. With the view of ascertaining the facts 

 as tar as could be known, an inquiry was addressed to the Hon. Jasper 

 Smith, consul for the United States at Funchal, Madeira, who has 

 answered very fully by citing the principal authorities having a bearing 

 upon the subject.^ 



The island was originally covered, as its Portuguese name implies, with 

 a heavy growth of timber. The north part is now sparsely wooded, but 

 the south side is almost wholly denuded, and cultivation is maintained 

 by an extensive and costly system of irrigation. Necessity has in some 



consisting of oaks, poplars, a few chestnuts, .and a large mulberry, the latter some- 

 what out in the field. The shade at sunrise extended across the whole, hut was nearly 

 off by ten o'clock. He observed that the chestnut had a very bad effect. The corn was 

 small and yellow, and the conical shape of the morning shadow could be traced to a 

 considerable extent in the sickly appearance of the plants. The black-oaks were in- 

 jurious, but not so much so as the chestnut ; the poplars very little so, and tne mul- 

 berry scarcely at all, although its shade remained longer than the others. After con- 

 sidering various suggestions, such as emanations from the trees and the like, he came 

 to the conclusion, which was probably the true one, that certain rays were absorbed 

 more by the loaves of one tree than another; aud going beyond this visible effect of 

 transmitted light upon vegetation, he raised the ingenious question as to whether the 

 light thus passed by the foliage might not have some x>roperties that might bo applied 

 as a medicinal agent to animal life. 



General Schuyler had remarked to him that the black oak was particularly injurious 

 to wheat. The locust tree, on the contrary, was thought extremely beneficifel to grass- 

 lands. — (Transac. of Soc.for Promotion of Ag,, Arts, and Manufac. 2d ed., i, IG'J.) 



'Mr. Smith cites "Madeira, its Climate and Sceiierij," by Robert White; "Climate 

 and lleteorologn of Madeira," by J. A. Mason, and " Climate and liesonrccs of Madeira," 

 by Dr. M. C. Graham, as affording detailed information upon this subject. He also 

 consulted Mr. James Yates Johnson, a resident of many years, who had edited a second 

 edition of Mr. White's book. The result was, that reliable information does not exist 

 for a long period back, and that any changes that may have occurred must bo inferred 

 from such statements as may be gathered concerning the early conditions. Tho oldest 

 traces of meteorological records go back 130 years. 



