48 PRINCIPLES OF AMERICAN FORESTRY. 



long-lived and perhaps slower-growing kinds, to afford 

 protection in later years, when the short-lived kinds have 

 died out. The soil and location have much to do in de- 

 termining the longevity of varieties; for instance, the Cot- 

 tonwood and Lombardy Poplar are generally short-lived 

 trees when planted on dry land, but when planted in loca- 

 tions where their roots reach the permanent water-level, 

 their period of life may be considerably lergthened, and 

 they may then even be regarded as long-lived trees. 



In starting a grove or windbreak on our Northern prai- 

 ries, there is probably no better tree to begin with than the 

 White Willow. It is quick-growing, rather long-lived in 

 most situations, makes good summer fuel, and renews itself 

 very rapidly from the stump. The Green Ash would 

 probably rank next as a pioneer tree. The White Elm, 

 and the Catalpa where it is hardy, are also very valuable 

 for this purpose, but, generally, should follow the White 

 Willow. The Cottonwood may sometimes, though very 

 seldom, be the best to use, but on average prairie land it 

 would be better if the White Willow or Green Ash were 

 always planted instead. 



After a good windbreak has been secured, it is safe to 

 plant out the hardy coniferous evergreens and such trees 

 as the Mountain Ash, European White Birch, and other 

 similar ornamental trees. Wind protection is beneficial 

 to all trees on our prairies and necessary for many of our 

 best ornamental kinds and often makes the difference be- 

 tween success and failure in growing them. 



Distance Apart. In the planting of groves, we should aim 

 to get the land shaded by the trees as soon as practicable, 

 and to keep it covered with a canopy of leaves. The 

 United States government recommended the planting of 

 trees four feet apart each way, with the idea that when so 

 planted they would quickly shade the ground and conse- 

 quently keep out grass and retard evaporation. Some 



