13 



trees are selected and cut every time a piece of wood is wanted. If 

 mature, dying, or worthless species are removed with care so as not 

 to injure the young growth, the grove will constantly improve in com- 

 position as the place of the overmature, diseased, and worthless trees 

 is taken by the better young growth. 



In an old woodlot which is badly run down, thinnings should begin 

 at once and be repeated often, but at no time should trees be removed 

 in such a way as to permit the formation of extensive areas of brush 

 and grass. If only large, overmature trees are present, they may be 

 cut in groups and the vacant area sown to acorns or nuts, or planted 

 with valuable species which can endure shade. In this way all the 

 large trees may be gradually removed and the area restocked with 

 valuable young forest growth. 



Great care should be exercised in all thinnings, especially on hill- 

 sides and ridges, not to cut out so heavily as to expose the soil to ero- 

 sion. This washing away of valuable soil and the formation of gullies 

 is each year destroying large areas of land in Iowa. Two hundred 

 square miles is said to be so lost each year in the United States, and 

 Iowa is doing more than her share toward increasing this figure. 



Harvesting the crop. — The best time to cut the trees to insure 

 sprout reproduction is in winter or early spring, and the wood of 

 sprouts which form in early spring has ample time to ripen before 

 winter. However, if the trees are cut between late July and Sep- 

 tember, during what lumbermen call "the second running of the 

 sap," and then left to lie for several days, until the leaves are com- 

 pletely wilted, seasoning will take place rapidly and thoroughly after 

 the posts or poles are peeled. Peeling should be done at once, and 

 the logs should be piled so that no part touches the ground. Posts 

 so treated will greatly outlast those of the same species and size cut 

 in winter and stacked on end without peeling. Trunks should not 

 be left lying on the ground before utilization, as this invites attacks 

 of fungi and insects and hastens rot. 



PLANTED TIMBER. 



SPECIES. 



When the people learned that the prairie soil was as valuable for 

 agricultural purposes as that of the hardwood regions, and the settle- 

 ment of the State began to extend westward from the timbered lands 

 along the Mississippi, there arose a need for the protection of the new 

 homes from the severity of hot and cold winds. Since the need was 

 immediate and seeds and seedlings of the softwoods were cheap, 

 easily obtained, and gave early results, the first plantings in the 

 State were of such species as silver maple, cottonwood, boxelder, and 

 willow. The silver maple has been more widely planted in Iowa than 

 any other tree because it makes good fuel, when seasoned under cover, 



[Cir. 154] 



