AN OUTDOOR LESSON ON TREES 239 



emerging, the sap running, seeds germinating and flowers 

 blooming. 



The soil conditions on the lawn and in the grove furnish 

 another interesting feature of comparison and study. In 

 the grove, you can demonstrate the decomposition of the 

 fallen leaves, the formation of humus and its value to the 

 tree. The importance of the forest soil as a conservator 

 of water and its relation to stream flow and soil erosion 

 can be brought out at this juncture. An eroded bank 

 and a slope covered with trees and shrubs would provide 

 excellent models for this study. A consideration of the 

 economic value of the trees would also be in place. 



3. Civic lessons reflected in trees: The community 

 life of trees in the grove, their growth, struggles for light 

 and food and their mutual aid can be brought out and 

 compared with the community life among people. The 

 trees may here be seen struggling with each other for light 

 and food, forcing each other's growth upward, some winning 

 out and developing into stalwart and thrifty specimens and 

 others becoming suppressed or entirely killed. On the other 

 hand they may be seen helping each other in their com- 

 munity growth by protecting each other from windfall and 

 by contributing to the fertility of the forest soil in drop- 

 ping their leaves and shading the ground so that these 

 fallen leaves may decompose readily. 



4. Enemies of trees : An old stump or tree may be seen 

 crumbling away under the influence of fungi and here the 

 children may be shown the effects of tree diseases both as 

 destroyers of life and as up-builders, because fungi turn 

 to dust the living trees and build up others by furnishing 

 them with the decomposed wood matter. 



Insects too, may be invading the old dead tree, and 

 something of their ; nature, habits and influences may be 



