Cool season grasses experienced the greatest increase in produc- 

 tivity. The aerial production of Agropyron smithii increased an average 

 of 529 percent in four exclosures, not including the spectacular 44,722 

 percent increase in the Bogr/Agsm c.t. exclosure. This species was the 

 highest producer in four exclosures in 1978 compared to one exclosure in 

 1977. Stipa comata , usually considered a cool season grass, increased 

 an average 442 percent in productivity in three exclosures. In the Stco- 

 Agsm/Bogr c.t. exclosure, A. smith ii out proauced S^. comata in 1978 but 

 not in 1977. Agropyron spicatum increased an average 279 percent in two 

 exclosures. 



As for warm season grasses, the aerial production of Andropogon 

 scoparius decreased in the Ansc c.t. exclosure and increased insignifi- 

 cantly in the Ansc-Agsp c.t. exclosure. Apparently the cool temperatures 

 prevented this species from efficiently using the additional precipita- 

 tion. Bouteloua gracilis , another warm season grass, increased by an 

 average of 297 percent in eight exclosures. Flowering in this species 

 was not prevalent and productivity appeared higher in 1976, a year of 

 near average precipitation. 



Smoliak's (1955) equation relating May-June precipitation to produc- 

 tion did not apply well in the Stco-Agsm/Bogr c.t. exclosure in 1973. 

 His equation predicts that 9.4 inches of precipitation would result in 

 682 kilograms/hectare, but aerial production was actually 1420 kilograms/ 

 hectare. This might be explained by the fact that the average May-June 

 precipitation used by Smoliak in developing his equation v/as 3.7 inches. 

 Also, the Stco-Agsm/Bogr c.t. exclosure apparently contained more S^. 

 comata and A. smithi i and less B^. gracilis than Smoliak's community. 



The higher precipitation of 1978 apparently resulted in more hetero- 

 geneity within exclosures. In 1977, production in replicates within 

 exclosures was non-nomogenous in three exclosures, while in 1973 five 

 exclosures appeared to be non-homogenous at the .05 probability level. 



Figures 2 through 4 show the dramatic 1973 increase in productivity 

 for the Stco/Bogr-Cafi , Agsp/Bogr-Cafi , and Bogr exclosures. Figures 

 5 and 5 show typical stands of tall coulee shrub communities and silver 



sagebrush stands. 



Otner interesting changes can be found by comparing tables 2 

 through 13 with the 1977 data (Prodgers 1978). In these tables, means 

 (X) and standard deviations (S) are in kilograms per hectare (for 

 pounds per acre multiply by 0.892). Coefficients of variation (CV) are 

 presented as decimals. N is the theoretical number of plots necessary 

 to obtain a sample mean within 20 percent of the true mean eighty percent 

 of the time, and n is the number of samples taken. 



Exclosures were divided into two replicates to determine the homo- 

 geneity of exclosures. The results of sum productivity values for 

 the replicates were compared using a t-test and the .05 probability level. 

 All exclosures except the Dist, Dist-Agsm, Stco/Bogr-Cafi, Bogr-Cafi/Stco 

 ana Agsp/Bogr-Cafi exclosures were homogeneous at the .05 probability level 



