PLANT MORPHOGENESIS FOR SCIENTIFIC MANAGEMENT OF RANGE RESOURCES 



213 



season influenced wind movement near the ground 

 on both sites (table 12). The average wind move- 

 ment on the grazed site at a height of 15 cm. was 

 2.7 km./hr. in June, as the vegetation began its 

 early development, and decreased to 1.6 km./hr. 

 in August when the vegetation was at its maxi- 



mum peak of development. By the end of August, 

 the vegetation had dried considerably, seed had 

 been shed, and fragments of stalks and leaves 

 were being broken off. mainly by wind action. 

 Consequently, wind movement at the 15 cm. 

 height increased, reaching an average velocity of 



Table 8. — Number of days on which maximum temperatures 

 exceeded 32° (90° F.) at different heights above grazed and 

 ungraded grassland during the 1970 season, June-September 









Height 



above 



ground 



surface — cm. 









2.5 



7.5 



15 



25 



55 



75 



120 



130 



145 



Grazed 

 Ungrazed 



66 

 76 



49 



87 



50 



54 



39 



34 



33 

 19 



35 



21 



30 



17 



26 



19 



Table 9. — Monthly average soil temperatures (C.) to a depth 

 of 120 cm. on grazed and ungrazed grassland during the 1970 

 season. (Average of all points measured.) 



Treatment 





Average soil temperatures- 



-°C. 







June 



July 



Aug. 



Sept. 



average 



Grazed 

 Ungrazed 



19.1 

 16.0 



23.5 

 19.8 



23.6 



20.2 



19.2 

 15.4 



21.4 

 17.9 



Table 10. — Weekly a re rage temperatures (C.) at different 

 depths in the soil for selected weeks during the 1970 season 

 under grazed and ungrazed grassland 







Grazed 









Ungrazed 





Depth 

 below 



















June 



July 



Aug. 



Sept. 



June 



July 



Aug. 



Sept. 



surface 



14-20 



12-18 



16-22 



13-19 



14-20 



12-18 



16-22 



13-19 





Beg. 



Beg. 



Beg. 



Beg. 



Beg. 



Beg. 



Beg. 



Beg. 



1.2 



19.4 



26.1 



25.6 



14.4 



19.4 



23.9 



22.2 



12.8 



2.5 



17.2 



23.9 



22.2 



11.7 



18.9 



23.9 



22.2 



12.8 



7.5 



21.1 



26.7 



25.0 



14.4 



18.3 



22.8 



21.1 



12.8 



15 



20.6 



26.1 



25.0 



15.0 



17.8 



22.2 



20.6 



12.8 



25 



19.4 



24.4 



23.9 



14.4 



16.7 



20.6 



20.0 



13.3 



55 



17.8 



23.3 



23.3 



16.7 



14.4 



18.3 



18.9 



14.4 



75 



17.2 



22.2 



22.8 



17.8 



12.8 



16.7 



17.8 



15.0 



120 



13.9 



18.9 



20.0 



17.8 



11.1 



14.4 



16.1 



15.0 



