8 



posts, repair material, and fuel they will produce, they may be of great 

 value in the ultimate reclamation of the soil by taking up immense 

 quantities of water and depositing layers of organic material on the 

 surface. 



NATIVE TIMBER. 

 DISTRIBUTION. 



When white men came to Iowa it is estimated that a fifth of the 

 State was forested. The eastern portion of the State was pretty well 

 covered. The best growth was along the larger rivers, but it often 

 extended many miles away from the banks. Occasional small groves 

 were found on the prairies. Through the southern and western parts 

 and along the Des Moines Kiver and its tributaries in the central part 

 there were scattered groves. 



The principal tree species in the early forests were practically the 

 same as those found to-day, bitternut and pignut hickories, and black 

 walnut; white, bur, red, yellow, and swamp white oaks; soft, or silver, 

 and hard, or sugar, maples; white and green ash; white, slippery or 

 red, and cork elms; hackberry, basswood, cottonwood, black willow, 

 sycamore, honey locust, and coffeetree, besides others of less im- 

 portance. 



NATURAL EXTENSION. 



Where natural extension of timber took place, it spread from the 

 main bodies along the Mississippi and Missouri rivers and followed the 

 tributaries of those rivers. That it did not extend farther up the 

 streams and outward across the prairies was due principally to prairie 

 fires, which annually and often semiannually swept over a large part 

 of the State. Natural extension was more uncertain and slower in the 

 western part of the State than in the eastern, because of less abundant 

 rainfall, greater exposure to hot, dry winds, and greater frequency of 

 prairie fires. In many cases forest growth extended farther up the 

 southern bank of streams than the northern, and covered larger areas 

 on that side. This was due probably to the fact that snow was not 

 reached by the sun as quickly on the southern bank, and so lasted 

 longer. The spring fires destroyed the trees on the dried-out northern 

 bank, but were checked by melting snow on the other side. 



As settlement, which began in the timbered portions of the eastern 

 part of the State, extended westward across the prairies, many of the 

 causes of prairie fires were removed and immediately the forest growth 

 began to extend farther up the streams and back to the uplands. 



CONDITION. 



The original timber areas consisted largely of scattered groups of 

 trees surrounded by brush and grass. In the eastern part of the State, 



[Cir. 154] 



