50 



PRINCIPLES OF AMERICAN FORESTRY. 



Mixed Plantings, when properly made, ha^'e the follow- 

 ing advantages: (1) They make possible the growing of 

 species that form a projtection in the least possible time, 

 and still have, coming on in the same grove, longer-lived 

 and better kinds to take their places. (2) Many kinds that 

 are sqmewhat tender are helped very much by being grown 

 among the h ardier kinds un til well established. In this 

 case the protecting trees are called nurse tre es. The 

 Scotch Pine is seldom a success when standing alone on 

 our Western prairies, but wlien partially protected by some 



Fig. 4. — A good tree claim in Minnesota near the Dakota line. 

 Located on high prairie. Soil very dry. 



deciduous tree it stands very well. The same is generally 

 true of Hard Maple, Catalpa, and Black Walnut toward 

 their northernmost limits. (3) In good mixed plantings 

 the ground is more likely to be properly shaded and pro- 

 tected from^winds than it would be in clear plantings of 

 such open-foliage species as the Cottonwood or White Elm 



