PLAN"T SUCCESSION AND RANGE MANAGEMENT. 61 



rying capacity is far below normal because of the use of established 

 bed grounds. 



Contrary to the consensus of opinion among stockmen and others, 

 the reduction in the forage crop on bed grounds can not be classed as 

 temporary. The belief prevails that the large amount of fertilizer 

 contained in the soil on the main part of a bed ground, and on the 

 lands adjacent thereto, will favor the most rapid and thorough re- 

 vegetation. Experimentation does not substantiate this opinion. 



In the plot shown in figure 25^ after 5 years of protection against 

 grazing, only a sparse stand of vegetation had gained a foothold, the 

 cover being composed chiefly of species of the early-weed stage 

 which are distinctly transitory, notabl}^ Douglas knotweed, goosefoot 

 or lamb's-quarters, and tansy mustard, in addition to a few species 

 which have been shown to be forerunners of the more permanent 

 second-stage cover. In addition, the average height of the different 

 species, as well" as the depth of their root systems, was considerably 

 less than over the range generally. This delayed colonization is 

 accounted for by the physical rather than by the chemical condi- 

 tion of the soil. To be sure, the abnormally large amount of avail- 

 able nitrogen and other salts in the soil on bed grounds has a ten- 

 dency to promote the height growth of the plant somewhat at the 

 expense of seed production; but since a large amount of seed is de- 

 posited annually on the bed ground, it is not probable that the organic 

 deposits in the soil have any appreciable effect on the rate of the 

 invasion or the extent of the establishment of the vegetation. It 

 is well known, on the other hand, that the soil on bed grounds is 

 packed exceedingly hard. So firmly packed is the surface on long- 

 used bed grounds that nearly all the superficial seed either fails to 

 germinate or the seedling dies as soon as the food stored in the seed 

 is exhausted. As a rule, the radicle of the germinating seed fails 

 to extend itself into the soil to a depth great enough to reach adequate 

 available moisture. Containing, as the local soil does, a large per- 

 centage of clay, the trampling, especially in ,v/et weather, tends to 

 produce the single-grain soil structure, which is most unfavora,ble 

 to establishment and groAvth of vegetation. 



SUCCESSION ON MODERATELY DEPLETED RANGE GRAZED AN- 

 NUALLY PRIOR TO SEED MATURITY COMPARED WITH SUC- 

 CESSION ON SIMILAR RANGE PROTECTED YEARLONG. 



In certain stages of premature grazing or overstocking, the more 

 hardy and persistent perennial plants may become so weakened that 

 all reproduction is temporarily arrested. Long before this condi- 



1 The plot of which figure 25 is typical was fenced against grazing in 1912, prior to 

 which it had been heavily used as a bed ground for several successive years. The bisect 

 here shown traverses the plot and represents a strip 3 inches wide and 16 feet long. 



