BANGE IMPROVEMENT BY DEFERRED GRAZING. 7 



ESTABLISHMENT OF SEEDLING PLANTS. 



Even if a crop of fertile seed has germinated there is no definite 

 assurance of material increase in the forage stand. The establish- 

 ment of forage seedlings, especially early in the season, depends 

 largely upon climate and soil conditions. 



During the germinating period the soil is invariably well supplied 

 with moisture. In the higher mountains rather severe freezes are 

 common, and as a result of alternating extremes in temperature the 

 soil heaves. When this takes place the seedling roots, then poorly 

 developed, are partly lifted out of the soil and the growth of the 

 plant is arrested. As the season advances the temperature rises 

 and the moisture in the surface soil is largely lost, so that only the 

 deeply rooted and more vigorous plants survive. The loss varies 

 from 20 to 70 per cent, depending chiefly upon the extent to which 

 the soil heaves and the development of the seedling roots at the time 

 the disturbance occurs. (PI. II.) 



On the lower elevations freezing does not usually occur after the 

 seed has germinated, but because of the relatively high temperature 

 the soil dries out seriously, so that even there those seedlings which 

 are poorly planted, and therefore poorly rooted, are likely to be lost. 



The thoroughness with which the seed is covered before germina- 

 tion and the character of the soil, therefore, are everywhere important 

 factors in establishing seedling stands. In hard-packed soils, like 

 those of much-used bed grounds, sheep trails, and the like, the seed- 

 lings have difficulty in extending their roots, and the loss is natu- 

 rally great. Heavy loss also occurs on warm, exposed situations, 

 but since these usually have a dense seedling stand in the spring, the 

 final stand compares well with that of more favorable localities. 



Once they have passed through the first six weeks of their existence, 

 seedlings are not likely to be affected by drought or adverse tempera- 

 ture. The root system develops rapidly in the autumn of the first 

 year, which not only protects the plant from winter killing, but in- 

 sures it against moderate gullying and drought the following season. 



During the second year of growth the young plants develop a 

 splendid root system. (PI. III.) This has penetrated deep enough 

 into the soil before the usual spring drought period to enable it to 

 continue its rapid development, and at the close of the season the 

 deepest roots often extend 6 inches below the surface. In the case of 

 some of the bunch grasses from 20 to 40 basal leaf blades (root leaves) 

 from 3 to 5 inches long are produced. By autumn of the third year 

 the perennial plants attain full development and produce fertile 

 seeds. From 3 to 5 flower stalks are usually sent up, and leaf blades 

 and root growth are very prominent. (PL IV.) 



So far the discussion has dealt with the loss of seedlings under 

 purely natural conditions. It is plain, however, that grazing, especi- 



