EEPKODUCTION OF WESTEBI^ YELLOW PINE. 



45 



Table 13. — Effect of cutting, herbaceous coiner, and grazing upon survival and 

 development of seedlings. 



Month and situation. 



August, 1920: 



Open range- 

 Stump patches 

 Natural areas . . 



Inclosure— 



Stump patches. 

 Natural areas. . 

 November, 1920: i 



Open range — 



Stump patches. 

 Natural areas.. 



Inclosure — 



Stump patches. 

 Natural areas . . 

 August, 1921:1 



Open range — 



Stump patches. 

 Natural areas . . 



Inclosure — 



Stiunp patches. 

 Natural areas . . 



Number 1919 seedlings. 



Basis, 



square 



feet. 



300 



800 



200 

 400 



700 



500 

 400 



400 

 900 



400 

 400 



Total. 



34 

 224 



17 

 139 



33 

 147 



43 



112 



Per 



square 

 foot. 



0.113 

 .280 



.08.5 

 .347 



.047 



.184 



.280 



.025 

 .083 



.002 

 .2:35 



Per 



acre. 



4,900 

 12,200 



3,700 

 15,000 



2,000 

 8,000 



3,700 

 12,200 



1,100 

 3,600 



100 

 10,200 



Grazing. 



Killed, 

 per cent. 



Injured, per cent. 



Serious. 





Moder- 

 ate. 



3 60 

 31 



1 The natural plots are identical throughout, but new plots were selected for each examination in the 

 stump patches. 



2 Although none were classed as dead, most of those classed as severely injured will not survive. 



3 The August record of grazing injury includes all seedlings showing evidence of injury at that time and 

 probably injuries of the preceding fall and spring. Since this examination was made at the close of a period 

 of vigorous growtli, the injuries could not readily be classified as to severity or time of occiuTence. 



The mortality from September, 1919, to June 1. 1920, was less than 

 during the much shorter period from June 1 to August 1, 1920. The 

 bulk of the loss during this latter period is known to have occurred 

 during the first two weeks of 3\x\y. just prior to the beginning of the 

 summer rains, the most critical drought of the year and in fa,ct the 

 only severe drought which the 1919 seedling crop had experienced. 

 The foregoing relationships were repeated in 1921. Comparatively 

 light losses occurred between August and November, 1920. So far 

 the records clearly point to drought as the dominating factor, whether 

 it is associated with clay content of the soil or with root competi- 

 tion. Conclusions as to the ultimate advantages or disadvantages 

 of cultivation can be reached only after longer records are available, 

 and will probably require a detailed analysis of each plot from the 

 standpoint of soil and herbaceous vegetation, as well as seedling 

 survival. 



Denudation hy overgrazing. — Eegardless of the final outcome with 

 respect to survival, the fact is established that the elimination of 

 ground cover by deep cultivation under the conditions here described 

 is unfavorable to germination. The reason is that on clayey soils 

 the surface tends to pack and dry out more where the natural vege- 

 tation is removed than where it is left undisturbed. These conclu- 



