48 



BULLETIN 1105, U. S. DEPARTMENT OF AGRICULTURE. 



stump patches are quickly invaded by the more aggressive annuals 

 and perennials of the weed type. The time required for the per- 

 manent grasses of the subclimax stage to establish themselves de- 

 pends upon the amount of leaf litter and the extent to which they 

 were shaded out. On two fenced areas the subclimax grasses, Fes- 

 tuca arizonica and Muhleribergia montana, have in some instances 

 regained complete possession in 12 years. More often, as shown in 



15000 



14-000 

 U I3000 

 ^12000 



<r 



UJl IOOO 

 0. 









<- 

















LEGEND 

 X Open range, stump patcnes 





2 Open range, natural areas 



3 Enclosure, stump patcnes 

 4: Enclosure, natural areas 



* 



> 



U Total number ^"Large^ 



E Killed or injured bygrazing- 

















i 



i. 



in 

 o 



Z 9000 



J 

 geooo 



Id 



10 7000 



G\ 



Cs 6 000 



q 5OO0 



E 



Id 4-0OO 



m 



^ 3000 



z 



2000 



IOOO 





















: 



p 































1 































f 



j 







> 



J 



3 













1 ' 1 















s 

 ^ 







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I 1 







a 



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J v. 





) 



AUGUST,I920 N0VEMBER.I920 SEPTEMBER ,I92J 



Fig. 6. — Effect of cutting, ground cover, and grazing upon seedling survival. 



Plate IX, the stump patches are still occupied mainly by weeds, 

 including such species as lupine (Lupinus hillii), vetch (Vieia 

 americana) , lambs' quarters {Cherwpodiwm album), goldenrod 

 {Solidago nem-oralis), June grass (Koelerla cristata), and squirrel- 

 tail (Sitanion sp.). Invariably the vegetation on stump patches, if 

 ungrazed, is of extraordinary luxuriance, owing partly to the presence 

 of decayed leaf litter, but mainly to the elimination of active tree 

 roots. Under intensive grazing, particularly by sheep, the vegetation 

 on the stump patches, being generally of a succulent type, is so 

 closely cropped that from a distance the ground looks absolutely 



.. 



