S 1.500 



■ 1947 (NORMAL RAINFALL) 



■ 1948 I VERY DRY) 

 1949 (VERT WET) 



■ 3-TEAR AVERAGE (Po'obolic regression) 



14 26 12 26 



15 29 13 2' 

 AUGUST [SEPTEMBER OCTOBER 



Figure 22. --Cumulative grass pro- 

 duction on very open forest range 

 dominated by bluestem grasses. 

 Central Louisiana, 1947-49. 



of close and repeated grazing on 

 the production and nutritive value 

 of range forage. 



Grass production on an un- 

 grazed range with very few trees 

 was about 2, 121 pounds per acre 

 (air-dry) during 1947, a year of 

 near-normal rainfall. In 1948, 

 when there was a record drouth, 

 production was 1,308 pounds of 

 grass, or 40percent less than the 

 normal year. The 1949 growing 

 season was comparatively wet, 

 and grass production jumped to 

 3, 083 pounds or 42 percent above 

 the average year. 



A "normal" grass produc- 

 tion curve, drawn from these data, 

 showed that about half of the grass 

 was produced by June 1, 75 percent by July 22, and 90 percent by 

 September 5. Further, there was enough winter- spring moisture each 

 year to insure 1,200 to 1,500 

 pounds of grass by July 1. Growth 

 thereafter varied greatly with the 2C 

 rainfall (fig. 22). 



Close and repeated har- 

 vesting seriously reduced grass 

 production. Areas harvested 15 

 times during the season produced 

 only 1,300 pounds of grass per 

 acre in 1947, while areas har- 

 vested only at the end of the 

 season yielded 2, 121 pounds (fig. 

 23). Furthermore, 35 to 50 per- 

 cent of the grass stand was killed 

 by this close harvesting in just 

 one season. It was clear that 

 heavy grazing will materially re- 

 duce grass production the first 

 year and, if continued, will de- 

 stroy the valuable bluestem 

 gras ses. 



■ UN0ISTURBED 

 TWICE 



- 4 TIMES 



■ 7 TIMES 



■ 15 TIMES 



FORBS 



Figure 23. --Cumulative production 

 of herbage under 5 harvesting fre- 

 quencies. Very openforest range in 

 central Louisiana, 1947. 



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