110 
THE GARDEN OF THE WORLD 
least, to produce a tree large enough for lumber. 
After our trees were gone, we discovered an¬ 
other service that forests do for man. They 
prevent floods. The roots of trees hold the 
moisture and let it go very slowly. When the 
trees are gone, the fast melting snow or heavy 
spring rains carry the soil away because there is 
nothing to hold it. Many hillsides have been 
washed bare of soil when the trees were either 
cut down or uprooted. 
The United States government is trying very 
hard to save the forests which are left and to 
plant new forests to replace the old ones. The 
government hires forest rangers to watch for 
forest fires, as many hundreds of trees are lost 
by fire each year. The government also tries 
to persuade lumber companies to plant a new 
tree every time an old one is cut down. 
All trees are beautiful, and most of them are 
useful. They grow usually in family groups. 
The northern forests are made up of conifers or 
soft wood trees. They are called conifers be¬ 
cause they have cones which hold the seeds. 
