October io, 1888.] 



Garden and Forest. 



393 



save our forests. The time has come for this intelligent 

 American people to follow the lead of France, Germany, 

 Austria and the civilized powers of the world in averting, by 

 timely measures, a great disaster. I shall now briefly set forth 

 the manner in which the beneficial effects of forests in agri- 

 culture are produced. 



The normal evaporation from bare land is much in excess 

 of that from lands in woods. An experiment made with two 

 jars of equal size, covered with wire gauze to protect them , 

 from flies and insects, one set under a bush and the other in a 

 place sixty feet from the suri'ounding trees, but thus protected 

 from wind, showed the evaporation in the open to be more 

 than double that imder the bush, the exact figures being; 

 bush jar, .863 evaporation; jar in the open, 1.854. 



Mr. W. Blore, who made this experiment, calculated that, in 

 the 102 days of average dry season at the Cape of Good Hope, 

 the excess of the evaporation from a burned or bare district 

 over a bush or forest covered one would be 384,000 gallons 

 per acre, or 384,000,000 gallons for a thousand acres. 



Other experiments in England show that the evaporation 

 from an open vessel in a room is eight inches in a year, 

 while in a field or open place it is estimated at between thirty 

 and forty inches. The soil in a forest being protected by the 

 trees to a certain extent, and thus under cover, we may infer 

 that evaporation would be less under such conditions than in 

 an exposed place. It is a matter of common observation that 

 roads running alternately through woods and open country 

 remain longest moist in the woods. Railroad cuts show the 

 same difference; houses in forests are damper than those in 

 the open. These facts go to show that evaporation from the 

 soil is slower in a forest than elsewhere. The only exception 

 to this is where water is in excess. The evaporation activity of 

 the trees is then excited to such an extent as to neutralize 

 their protective effect upon the moisture in the soil itself. 

 Thus trees in a swamp have a draining effect, while upon dry 

 soil they will maintain humidity. 



Nothing is better authenticated, both by scientific and gen- 

 eral observation, than this last effect. In California we have 

 learned to help the soil and maintain moisture \>y making the 

 soil a mulch for itself by cultivation, that is, by keeping the 

 surface pulverized. But this artificial process is unprofitable 

 upon the steep mountain sides, where our forests are of most 

 importance. Such an attempt would only result in the wash- 

 ing away of what soil there is on the mountains. In this con- 

 nection it may be well to note the value of thorough cultiva- 

 tion. The driest soil contains thirteen per cent, of moisture. 

 Schubler's experiments show that soil that weighs about 

 'a. thousand tons per acre, when thoroughly pulverized and 

 completely dried, will absorb from the atmosphere in twenty- 

 four hours : 



Sandy clay, . - . Twenty-six tons of water. 



Loamy " - - - Thirty 



StilT " - - - - Thirty-six ' 



Garden mould, - - Forty-five " " " 



We are all familiar with the absorptive capacity of common 

 salt. Carbonate of potash has also notable affinity for moist- 

 ure, but it is the humus of the forest that possesses this 

 power more than any other soil, absoi'bing to again give off 

 from two to four times its weight in water. Forests mulch 

 the ground under them. It therefore becomes plain, that 

 forest fires, when not destructive to the trees, diminish the 

 capacity of the forest for retaining moisture. The trees also 

 protect the earth under them from the heat of the sun. Soil 

 in the open is raised in temperature by the sun at a depth of 

 one foot, fifteen degrees more than in a forest; consequentlv, 

 the abstraction of moisture is correspondingly larger in the 

 open. The difference is as 130 to 1,000 in favor of the for- 

 est. On the other hand, the experiments cited by Marsh show 

 that in winter soil has been frozen to a depth of six feet on a 

 bare knoll, while in the adjoining forest the soil was uniformly 

 above the freezing point. This is most important in Califor- 

 nia in our high mountains, for rains upon frozen ground 

 must run oft' without penetrating. So bare places would not 

 act as reservoirs for later use, while the forested land would. 

 Forests protecting land from excessive heat, protect the 

 snows from rapid melting. The last place from which snow 

 disappears, at the same elevation and isothermal line, is the 

 forest. To the irrigators of parts of central and southern Cali- 

 fornia this is of great importance, for, with the forests, the 

 snow water of spring and early summer is long maintained, 

 while without them the melting of the snow must be more 

 sudden and the water resulting from it flow off in floods, so 

 it is dissipated and the life-giving water is gone when most 

 needed. 

 Another effect of forest action is that the snows in them 



melt from the ground side most and thus can reach the con- 

 duits that supply the springs, while snow upon frozen ground 

 melts from above and runs off rapidly. The desiccating eft'ect 

 of winds is often great. Our dry winds in this State do much 

 damage to fruit trees and dry the grain in the milk, diminish- 

 ing the crop. Forests have a modifying influence upon such 

 winds. In fact, a dry wind cannot originate in a frosted coun- 

 try, and, as it passes over forests, is diminished in intensity; 

 even a belt of trees will have a pronounced protective influ- 

 ence on crops and trees to leeward of them and for some 

 distance to windward also, for the trees bank up the air on 

 this side, as is known by hunters, who, in striking a light, 

 place the shelter of their hand on the lee side, having the light 

 in the direction from which the wind comes. 



Trees protecting the ground from the rapid radiation of 

 heat, prevalent in bare places, diminish frosts. Thus a plant 

 under shelter of a tree is less likely to be frozen than if it were 

 in the open ; but trees protect in this respect in another way. 

 Megucher's experiments in Lombardy show that trees, like 

 animals, maintain a constant temperature, that is somewhat 

 modified, doubtless, as it is in animals, by hibernation. This 

 temperature for trees is fifty-four degrees; forests in a coun- 

 try, therefore, have a similar effect to the sea. They maintain 

 a more even degree of humidity and of temperature and 

 equalize the climate. 



The deposit of dew is more copious upon vegetation than 

 it is upon the soil. Experiments shoAV the difference to be 

 more than double ; the exact figures are : for grass, 4.75 ; for a 

 white surface, 2.00. 



In walking through grass or bushes after a dew the moist- 

 ure will be apparent as compared to bare land. Fogs and 

 mists are to a considerable extent condensed by the foliage of 

 bushes and trees, and drip from them to the ground. On 

 misty mornings I have frequently been wet through when 

 walkmg- in the chapparal of the Sierra Madres, while on the 

 bare hillsides no moisture was visible. At Santa Monica where 

 I spend the summer, on foggy days the trees may be observ- 

 ed to drip with water, and in thick fogs the drip is so con- 

 tinuous as to suggest rain as it drops on the fallen leaves. 



Santa Monica, Cal. Abbot Kinney. 



Correspondence. 



Forest Planting in New England. 



To the Editor of Garden and Forest : 



Sir. — I have on a farm here some acres of land aftbrding but 

 poor pasturage, some of which is grown to bushes and some 

 little clear land formerly devoted to grass. I have been led by 

 Garden and Forest to consider the advisability of devoting 

 the land to forest plantations of Ash, Chestnut or White Pine. 

 If I am not trespassing too much on your time and kindness, 

 will you please tell me what books or publications would be of 

 service to me in learning the best method of planting and the 

 result of experiments made in the planting of forests in New 

 England. 



My land differs from the sandy soil of the Cape, where I 

 think successful experiments have been made, in being 

 stronger and of a kind considered good grass land. Whom 

 would you recommend as an expert in the matter.? 



Truly yours, William Simes. 



Petersham, Mass. 



[There is no American Manual of Arboriculture, and the 

 foreign works upon this subject, based upon conditions 

 dissimilar to those which prevail in this country, have 

 little practical value here. The general principles of tree 

 planting, however, applicable to the United States as well 

 as to Europe, will be found in "The Forester," by James 

 Brown, published in Edinburgh, 1882, and in "Arboricul- 

 ture," by John Grigor, Edinburgh, 1868. There are papers re- 

 lating to tree planting in Massachusetts, in the Reports of the 

 Secretary of the State Board of Agriculture of that State for 

 1875, 1878, 1882 and 1885, and there is much information 

 upon this subject, valuable and otherwise, scattered through 

 the reports of Agricultural Societies and Boards of Agricul- 

 ture of almost all the Northern and Western States. The 

 most interesting plantations of forest trees made in IVIassa- 

 chusetts are those of White Pine in Middleborough, Rayn- 

 ham and Bridgwater, of which an account will be found in 

 the Transactions of the Massachusetts Horticultural Society 

 for 1885; the Pitch Pine plantations in Orleans and in other 

 towns on Cape Cod, of which a description will be found 



