Nov. i6. 1914 



Revegetation of Range Lands 



107 



bunch-grass seed showed a fair viability, the maximum germination 

 obtained being 25.2 per cent, but the average of a great number of tests 

 made under various degrees of temperature gave the figure in the table. 

 In general, seed of the less desirable species, such as white foxtail and 

 reed-grass, show a higher percentage of germination than that of moun- 

 tain bunch-grass, short-awned brome-grass, and others. The germina- 

 tive power of the seed was generally lowest in 1907, owing to the low 

 vitality of the vegetation due to previous early grazing. In subsequent 

 seasons on areas protected entirely from stock or until the seed had 

 matured there was a pronounced increase in the germinative power of the 

 seed. 



It will be seen from Table II that, in general, seed fertility decreases 

 with elevation, the average germination of the plants on the higher 

 ranges being only 28 per cent, as against 45.1 per cent for those on the 

 lower elevations. Even with the best conditions of growth and plant 

 vigor, the vegetation of the region must struggle to mature its seed 

 during a short and none too favorable growing season. The effect of 

 exposure and of low vigor of the vegetation (as indicated by the date of 

 maturity) on the germinative power of the seed is shown in Table III. 



Table III. 



-Effect of exposure and date of maturity upon germination of mountain 

 bunch-grass 



Series 

 No. 



Source of seed. 



South exposure 

 West exposure . 

 North exposure 

 East exposure . . 

 South exposure 

 West exposure . 

 North exposure 

 East exposure . . 



Feet. 



7,400 

 7,400 

 7>3oo 

 7,350 

 7,400 

 7,400 

 7.3°° 

 7. 3S° 



Date of 

 maturity. 



Aug. 20 

 Aug. 22 

 Sept. I 



...do 



Aug. 31 



...do 



Sept. 12 

 Sept. 14 



Germina- 

 tion. 



Per cent. 



14. O 

 9-5 



"■S 



II. o 



7.0 

 4-5 

 1-5 



The data in this table bring out two important facts: (i) There is 

 no difference in the vitality of the seed of mountain bunch-grass ripen- 

 ing before September i , provided the variation in the maturing period 

 does not exceed about 10 days. (2) There is a pronounced difference in 

 the viability of seed which reaches maturity by September i, as com- 

 pared with seeds ripened September 10 or later, the latter showing prac- 

 tically no germinative power. 



The same relationship between the germinative power of early and 

 late-maturing seed was observed in the course of field sowing in the natural 

 habitats, though in all such cases the germinative power of both classes 

 of seed was higher. 



