The Enemies of Trees 



work. After a fire is believed to be extinguished it often smoulders 

 and breaks out with renewed violence later on. Or it may seem 

 under control over most of its area, and by suddenly climbing 

 a dead tree be out of reach, start a fresh blaze among the treetops 

 and threaten a much larger territory. The broad-leaved trees 

 are less likely to spread a fire than the inflammable, resinous 

 conifers. 



Gracing as practised in this country is sometimes as destruc- 

 tive to forests as fire. Over-graiing is the proper term, for a 

 flock of sheep is generally kept in a section of woods until every- 

 thing green within reach has disappeared. Sheep nibble and 

 gnaw and crop roots and saplings, and their little feet pack and 

 tear open the leaf mould, trampling out the life of all young growth 

 they do not eat. They are especially destructive to young 

 coniferous growth. A lease of a tract for grazing generally 

 means desolation in the wake of the flock, as far as all under- 

 growth is concerned. Government lands have been grazed 

 to their lasting damage by sheep men without leave from 

 any authority. This is being stopped wherever reservations 

 are patrolled. 



Cattle do less harm in grazing than sheep and goats. They 

 do not keep so close together, their feet do not cut into the soil 

 so deep, nor do they strip all growths clean as they go, unless 

 driven to it by drought. Horses do less harm than cattle. Hogs 

 prevent much young growth by eating tree seeds, especially those 

 of beech, oak and other nut trees. 



Grazing should be prohibited in young woods, and permitted 

 but sparingly in old forests. In fact, a forest should have no 

 openings in its roof, and so no grass on the forest floor. 



ENEMIES OF CITY TREES 



Trees in cities lead a hard life. The air is charged with smoke, 

 soot and noxious gases. These clog the leaf doorways, thus 

 interfering with the tree's life processes. Paved streets and side- 

 walks prevent the proper ventilation and watering of the soil. 

 The roots need to breathe as well as the leaves. Leaks in sewer 

 pipes and gas mains often sufi"ocate a tree through its roots. 



Regrading and filling in change the ground level, and trees 

 are left with roots exposed or buried deeper than before. Either 



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