SHELTER-BELT DEMONSTRATIONS ON THE GREAT PLAINS. 27 



Of the tree species extensively tested, the following seem adapted 

 to the climatic conditions generally prevailing: Box elder, green 

 ash, white elm, and caragana. 



The following species which have so far been tested only in a 

 limited way give promise of being suitable for general planting: 

 Northwest poplar, chokecherry, buffalo berry, Russian olive, Black 

 Hills spruce, white spruce, blue spruce, Scotch pine, and jack pine. 



Extensive tests of the following species show that they are not 

 adapted for general planting : Norway poplar, Carolina poplar, Rus- 

 sian golden willow, and laurel-leaf willow. 



Careful preparation of the soil before planting, to conserve mois- 

 ture and work out grass and weeds, is a prime requisite far successful 

 tree planting. Clean summer fallow is the best tillage method to 

 practice for this purpose. 



Clean cultivation after planting is essential to the continued growth 

 of young trees. Neglect in this respect for a single season is likely 

 to result in serious damage to the trees. 



Insect and animal pests may cause considerable damage unless 

 precautions are taken against them. 



With such trees as box elder, green ash, and white elm, stock raised 

 from seed procured from native trees has shown greater hardiness 

 than that coming from more southern and eastern localities. Seed 

 for propagating an}' species for planting in shelter belts on the north- 

 ern Great Plains should come from a northern source. 



A standard spacing distance for trees in shelter belts has not yet 

 been determined. Present data indicate that for the average plant- 

 ing site in the area the 4 by 8 feet distance used in these demonstra- 

 tions is too close. Further infonnation is needed on this point. 



The experience of these five years of tree planting has shown con- 

 clusivel}^ that it is possible to start successfully a planting of trees 

 on the average upland farm site in the northern Great Plains. 

 Future investigation must show whether or not it is possible for 

 such plantings to maintain themselves after they have attained their 

 maximum growth. 



