6 



BULLETTlSr 1113, U. S. DEPARTMENT OF AGRICULTURE. 



Table 1. — Precipitation and seasonal evaporation at 10 field stations in the 

 northern Great Plains for the 5-year period from 1916 to 1920, inclusive. 



Station. 



Alti- 

 tude 

 (feet). 







Precipitation (i 



nches). 







Seasonal 



I 





Annual. 



















Nor- 















mal 















Maxi- 



Mini- 



Aver- 



Maxi- 



Mini- 



Aver- 



an- 

 nual.2 



mum. 



mum. 



age. 



mum. 



mum. 



age. 



11.38 



9.22 



10.15 



15.07 



10.31 



12.96 



17.05 



13.89 



5.82 



10.18 



18.21 



8.35 



12.81 



15.77 



13.18 



6.39 



10.11 



15.91 



7.85 



12.74 



14.96 



20.56 



8.44 



12.78 



25.89 



13.32 



17.03 



15.20 



17.53 



10.57 



13.29 



20.26 



13.53 



16.66 



17.55 



14.88 



4.85 



8.57 



19.24 



7.56 



11.68 



13.67 



15.63 



4.77 



10.74 



19.87 



9.90 



16.44 



16.61 



9.87 



5.31 



7.88 



15.14 



12.22 



13.62 



13.84 



12.41 



5.28 



8.60 



17.38 



8.56 



13.52 



14.72 



15.59 



8.53 



11.62 



19.09 



12.39 



14.79 



13.60 



Evap- 

 oration, 



onali 

 (inches). 



Maadan, N. Dak. . 

 Dickinson, N. Dak 

 Hettinger, N. Dak. 

 NeweU, S.Dak.... 

 Ardmore, S.Dak.. 



Havre, Mont 



Moccasin, Mont 



Huntley, Mont 



Sheridan, Wyo.3. . . 

 Archer Wyo 



1,750 

 2,543 

 2,253 

 2,950 

 3,557 

 2,505 

 4,200 

 3,037 

 3,790 

 6,017 



35.460 

 34. 158 

 32. 762 

 34. 174 

 37.274 

 35. 727 

 35.335 

 34.256 

 35.525 

 36.845 



■■ Seasonal precipitation and evaporation are for the 6-month period from Apr. 1 to Sept. 30, inclusive. 



2 Mean annual precipitation is the average of the entire record. 



3 Sheridan data, except mean annual precipitation, are for the four years from 1917 to 1920, inclusive. 



FcG. 2. — Tlie Yellowstone River valley at Pompeys Pillar in southern Montana, showing 

 native growth of western cottonwood, box elder, and green ash in the river bottom 

 and yellow pine on the adjoining hills. 



NOTES ON TREE SPECIES. 



In determining the adaptability of any tree species for planting 

 on the open prairie of this region, its ability to resist drought and 

 extreme cold is a factor of prime importance.. In this area of limited 

 moisture, late spring frosts, and early autumn frosts it is found that 

 many of the species adapted to shelter-belt use have a comparatively 

 short growing season. Their leaves are not put out until spring is 

 well advanced and terminal buds are generally set in late summer. 

 It naturally follows that the native tree growth found along the 

 rivejrs and in the coulees and on certain groups of hills throughout 



