SEVENTEENTH ANNUAL YEAR BOOK— PART VIII 



445 



Fig-. 7. — A ten-year-old windbreak of ji- 

 trees are 15 feet in height. 



■k pine trees. Many of the 



states. The bark is dark reddish-brown and has a scaly appearance. 

 The crown of the tree is very open and the foliage thin. The leaves or 

 needles are generally less than two inches in length and have a light 

 or yellowish green appearance. This pine will endure the poorest, sandy 

 soil; in fact, it has been planted with success in almost pure sand and 

 where the conditions during the growing season are dry and trying. 

 Like other trees, however, its best development is obtained on a good, 

 sandy loam soil. It is a short-lived tree, a rapid grower and a prolific 

 seeder. In its native range it is one of the first trees to come in after 

 the forest has been destroyed by fire. In central Iowa, on good soil, the 

 jack pine makes a somewhat greater height growth than either the white 

 or red pines during the first 10 or 12 years. 



The Wood: The wood is weak, light, fairly hard and rather coarse 

 grained. The lumber is generally knotty. The wood is not durable in 

 contact with the soil. It is not used extensively for lumber except where 

 more desirable woods are not available. The small trees make very satis- 

 factory box boards and they may be used for fence posts if given treat- 

 ment of creosote. 



Planting: The jack pine is not recommended for general planting in 

 Iowa, due to other more desirable species being available. Its per- 

 sistence on poor, sandy soils and Its rapidity of growth make it desirable 

 for use In restricted localities. 



For windbreak planting space the trees about 10 by 12 feet apart. For 

 commercial planting give them close spacing of about 6 by 6 feet in 



