FOREST PROTECTION. 141 



classed as frost tender trees, and those that are not liable 

 to this injury are termed frost hardy trees. Among 

 conifers, the Spruces and Balsams are much injured by 

 late spring frosts, while our Pines and the Tamarack, Red 

 Cedar, and Arborvitse are seldom if ever injured in this way. 

 Deciduous trees recover from such injuries more quickly 

 than Evergreens. Among the deciduous trees most lia- 

 ble to injury from this cause are the Ash, Mulberry, Oak, 

 Maple, Basswood, Black Walnut, Butternut, and Box- 

 elder, though they do not all suffer in the same degree. 

 Among those that are not sensitive to late frosts are the 

 Elm, Willow, Poplar, Birch, Hackberry, Wild Black 

 Cherry, and Mountain Ash. 



On account of this liability to injury from late frosts, 

 it is customary to study the probability of damage from 

 this cause in given locations, and to plant accordingly. 

 It will often be found that in certain low spots there is 

 greater liability to late frosts, while there is very little 

 injury from this cause on the higher lands. It is 

 customary among European foresters to protect young 

 seedlings of some kinds, particularly Beech, from late 

 frosts until they get up off the ground. For this pur- 

 pose Birches twenty or more feet high are encouraged at 

 intervals of thirty or forty feet, and the frost tender 

 plants, such as Beech and Spruce, are set out between. 

 The result of this arrangement is that the Birch, which 

 is frost hardy, quite successfully protects the frost 

 tender trees below it. After the frost tender trees are 

 well off the ground, as ten or fifteen feet high, there is 

 comparatively little danger from this source of injury, 

 and the Birch is removed. 



Sleet-Storms occasionally do much damage by break- 

 ing the limbs. Little can be done to relieve the trees, 

 but preventive measures may be taken. If no large 

 crotches are allowed to form in trees, and growth is kept 



