FARM AND FOREST. 297 



lies a fortnight to a month longer than in exposed positions and melts with less waste from 

 evaporation, the snow waters more fully penetrate the ground. Again, more snow is caught 

 and preserved under the forest cover than on the wind-swept fields and prairies. 



All these conditions operate together, with the result that larger amounts of the water sink 

 into the forest soil and to greater depths than in open fields. This moisture is conserved because 

 of the reduced evaporation in the cool and still forest air, being protected from the two great 

 moisture-dissipating agents, sun and wind. By these conditions alone the water supplies available 

 in the soil are increased from 50 to GO per cent over those available on the open field. Owing to 

 these two causes, then— increased percolation and decreased evaporation — larger amounts of 

 moisture become available to feed the springs and subsoil waters, and these become finally 

 available to the farm, if the forest is located at a higher elevation than the field. The great 

 importance of the subsoil water especially and the influence of forest areas upon it has so far 

 received too little attention and appreciation. It is the subsoil water that is capable of supplying 

 the needed moisture in times of drought. 



THE FOREST TEMPERS THE FARM. 



Another method by which a forest belt becomes a conservator of moisture lies in its wind- 

 breaking capacity, by which both velocity and temperature of winds are modified and evaporation 

 from the fields to the leeward is reduced. 



On the prairie, wind swept every day and every hour, the farmer has learned to plant a 



wind-break around his buildings and orchards, often only a single row of trees, and finds even 



that a desirable shelter, tempering both the hot winds of summer and the cold blasts of winter. 



The fields he usually leaves unprotected; yet a wind-break around his crops to the windward 



would bring him increased yield, and a timber belt would act still more effectively. Says a 



farmer from Illinois : 



My expenence is that now in cold and stormj winters fields protected by timber belts yield full crops, while 

 fields not protected yield only one-tbird of a crop. Twenty-five or thirty years ago we never had any wheat killed 

 by winter frost, and every year we had a full crop of peaches, which is now very rare. At that time we had plenty 

 of timber around our fields and orchards, now cleared away. 



Not only is the temperature of the winds modified by passing over and through the shaded 

 and cooler spaces of protecting timber belts disposed toward the windward and alternating with 

 the fields, but their velocity is broken and moderated, and since with reduced velocity the 

 evaporative power of the winds is very greatly reduced, so more water is left available for crops. 

 Every foot in height of a forest growth will protect 1 rod in distance, and several belts in 

 succession would probably greatly increase the effective distance. By preventing deep freezing 

 of the soil the winter cold is not so much prolonged, and the frequent fogs and mists that hover 

 near forest areas prevent many frosts. That stock will thiive better where it can find protection 

 from the cold blasts of winter and from the heat of the sun in summer is a well-established fact. 



THE FOREST PROTECTS THE FARM. 



On the sandy plains, where the winds are apt to blow the sand, shifting it hither and thither, 

 a forest belt to the windward is the only means to keep the farm protected. 



In the mountain and hill country the farms are apt to suffer from heavy rains washing away 

 the soil. Where the tops and slopes are bared of their forest cover, the litter of the forest floor 

 burnt up, the soil trampled and compacted by cattle and by the patter of the raindrops, the water 

 can not penetrate the soil readily, but is carried off superficially, especially when the soil is of 

 clay and naturally compact. As a result the waters, rushing over the surface down the hill, run 

 together in rivulets and streams and acquire such a force as to be able to move loose particles and 

 even stones; the ground becomes furrowed with gullies and runs; the fertile soil is washed 

 away; the fields below are covered with silt; the roads are damaged; the water courses tear their 

 banks, and later run dry, because the waters that should feed them by subterranean channels have 

 been carried away in the flood. 



The forest cover on the hilltops and steep hillsides which are not fit for cultivation prevents 

 this erosive action of the waters by the same influence by which it increases available water 

 supplies. The important effects of a forest cover, then, are retention of larger quantities of water 



