Nov. 16^ 1914 



Revegetation of Range Lattds 



III 



the relative air humidity and increases transpiration and evaporation 

 from the soil, it also decreases the available soil moisture. 



With the limited amount of precipitation during the growing period 

 in the region, the soil moisture gradually decreases as the season advances. 

 Low temperatures and lack of moisture in the upper soil often work 

 together to destroy seedlings, in that the seedling roots are first pushed 

 np by the heaving of the soil during freezing to a point where there is 

 not enough moisture available for growth. 



The seedhngs of no particular species seemed to suffer more seriously 

 than any other in the same situation. Individuals which sprang from 

 seed that had not foimd its way into the soil and which therefore had 

 comparatively shallow root systems were, of course, the most seriously 

 affected. 



Plants of the same species growing in the same situation often exhib- 

 ited contrasts in their ability to withstand drought, and when plants 

 growing in different kinds of soil were observed, the contrast was great. 

 This is shown in Table IV. 



Table IV. — Water content of soil at time 0/ death of forage seedlings 



Name erf plant, soil typ€, and .situatkm. 



Mountain bunch-grass: 

 Basaltic clay loam — 



Quadrat station 4 



Seeded area 



Do 



Quadrat station 4, seedlings in flats. 



Do 



Do 



Seeded area 



Gravelly clay loam — 

 Seeded area, seedlings in flats 



Do 



Do 



Do 



West slope 



Do 



South slope 



Do 



East slope 



Western porcupine grass: 

 Gravelly clay loam — 



West slope 



South slope 



East slope 



Short-awned brome-grass: 

 Gravelly clay loam — 



West slope 



South slope 



East slope 



Number 

 of succes- 

 sive days 

 of wilting, 



(?) 



Date of 

 death. 



July 



22 

 20 

 24 

 19 

 20 

 21 

 23 



19 

 19 



20 



18 



19 

 18 



19 



21 

 21 

 21 



19 

 19 

 18 



Percent- 

 age of 

 □onavail- 

 able 

 water. 



6.8 



6.3 

 6.8 

 6.2 

 6. I 

 6.2 

 7-2 



5-4 



5-7 

 S-4 



5-4 

 5-i 

 5-4 

 5.6 

 5.6 



5-2 

 5-4 

 5-2 



5-8 

 5-6 

 S-9 



Average 

 percent- 

 age of 

 nonavail- 



able 

 water for 



each 

 species. 



6.51 



5-5 



S. 26 



5-75 



