growth is generally limited to stream banks, farm tree planting is done 

 primarily for windbreaks. Holding snow to increase soil moisture, check- 

 ing wind velocity to reduce drying and blowing of the soil, and greatly 

 improving the appearance of the farmstead are protective and aesthetic 

 values of the farm woodland. 



The forests far removed from the farm serve agriculture in many areas by 

 holding the soil in place on slopes and along the banks of streams. Where 

 forested slopes have been logged, many thousands of acres of rich agricul- 

 tural bottom land have been ruined by deposits of sand, gravel, and boul- 

 ders, washed down from the bare slopes. In some States, particularly in 

 the South, tree planting on gullied parts of farms to check erosion is one 

 means of putting otherwise waste areas to profitable use. 



Water supply. — Irrigation supplies the lifeblood of certain agricultural 

 communities. More than 240,000 farms, about half the total number in the 

 11 Western States, are dependent upon irrigation for watering crops. A 

 large part of the water used to irrigate these farm lands comes from neigh- 

 boring forested mountains (fig. 13). 



The investment in irrigation agriculture has been estimated at more than 

 6 billion dollars, and the value of the crops produced at 900 million dollars 

 in 1929. Without the forest cover on the watershed, the flow of water 

 would be irregular and uncertain, larger and more costly storage reservoirs 

 would be necessary, and great losses in silting of reservoirs and ditches 

 would follow. 



How Do Forests Serve in Study and Leisure? 



An outdoor school. — Nature has set up a school in the forest. The varied plants 

 and animals, the scents, sights, and sounds open new books to those who wish 

 to learn. The forest offers a range from the ABC's of nature study to the 

 complexities of ecology. Every level of understanding from the pictured 

 primer to scientific research may find satisfaction in the forest environment. 



Recreation. — Forests play an increasingly important role in leisure activ- 



Figure 12. — What are the three marketable products from this forest area? 



24 



