48 



BULLETIN 1105, V. 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 Muhlenbergia Tnontan/L, have in some instances 

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



isooo 



14-000 



13000 



I2O0O 



< 



a. 



UJI 1000 



a 

 I 



10000 

 9000 

 8000 

 7000 

 6000 

 5000 

 4-0O0 

 3000 

 2000 

 lOOO 



LEGEND 



X Open, range, stump patches 



2 Open range, natural areas 



3 Enclosure, stump patcnes 



4 Enclosure, natural areas 



U Total number M Large'^H Killed or injured bygrazing- 



AU GUST, 1920 



Fig. 6. — Effect of cutting 



NOVEMBER, !920 SEPTEM B ER . 1921 



;round cover, and grazing upon seedling survival. 



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

 including such species as lupine {Lupinus Jiillu), vetch (Vicia 

 americana)^ lambs' quarters {CTiemopodiwm album), goldenrod 

 (jSolidago nenioralis). June grass {Koeleria 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 



