u. 

 O 



400 



CO 3 

 -J -» 

 I 



a d 

 -I tc 



lU 0. 



< 



300 - 



200 - 



LU 



r < 100 - 



a 

 < 

 ffi 



cc 



UJ 

 X 



^HKi RUSSIAN WILDRYE 

 ™™™ GREEN NEEDLEGRASS 

 MI IB CRESTED WHEATGRASS 

 llllilii INTERMEDIATE- PUBESCENT 

 WHEATGRASS 



'7» 



-L 



J. 



2 3 4 5 6 

 YEARS AFTER ESTABLISHMENT 



Figure 5 — Effects of stand age on herbage yield in the 

 Northern Great Plains per inch of April through June 

 precipitation (after White 1985). 



precipitation year (Sneva and Britten 1983) were approxi- 

 mately 543 lb per acre. About 700 lb of total herbage 

 increase per acre was produced 5 years after chaining in 

 59 projects in southern Utah (Phillips 1977). Many of 

 these projects could have been near peak production if 

 they followed the trend illustrated in figure 3. The data 

 of Payne and Busby (1980) showed an average of only 

 379 lb per acre of grasses with few forbs were produced on 

 18 chainings 6 to 25 years old on National Forests in 

 Utah. Although production of shrubs was not determined, 

 the rate of grass production was about the same as oc- 

 curred on the most recent treatment areas at Oak 

 Creek— Church Hills and Clay Springs (-350 to 400 lb per 

 acre). The average annual precipitation for these sites 

 was approximately 14 inches or about the estimated long- 

 term mean for the study areas at Oak Creek. 



CONCLUSIONS 



UJ 



o 

 < 



700 1- 



600 - 



500 - 



q" 400 - 



300 



200 



100 - 



2 4 6 8 10 12 



YEARS AFTER TREATMENT 



Figure 6 — Herbage yields by number of growing 

 seasons after control of juniper and pinyon (after 

 Arnold and others 1964). 



Direct comparisons of different treatment areas are 

 difficult because many important factors such as weather, 

 soils, grazing history, and plant co.ii position are often not 

 recorded. However, general patterns in the data provide 

 some guidance. Results from the Oak Creek Mountain 

 Range Evaluation Area, examined from several view- 

 points, and other published results support a conclusion 

 that RPA assumptions and soil report estimates of herb- 

 age and shrub production potential were overly optimistic 

 for average long-term grazed conditions in central Utah 

 pinyon-juniper. The swale bottom topographic position 

 was the only situation with sufficient productivity to ap- 

 proach expectations of the RPA coefficient matrix. The 

 estimate of overall forage production provided by the 

 Forest Service environmental statement was the most 

 accurate. 



Factors that cause difficulties in making accurate site 

 predictions from assessment matrices include: (1) few 

 guides for positioning a specific site within the assess- 

 ment matrix; (2) lack of information on grazed or un- 

 grazed situation of original data sources; and (3) lack of 

 information concerning the age and original seeding suc- 

 cess of seeded stands. 



many Intermountain chaining and seeding efforts 

 wherein the initial stands are often thin in comparison to 

 stands obtained by more intensive seeding techniques. In 

 such instances, a continued thickening of the stand often 

 results in continued gain in production for several years 

 because the total rooting zone was not initially occupied. 

 Depending upon initial conditions and plant composition, 

 we might expect a difference of up to 8 years among 

 stands as to when their peak production is achieved. 



In other reported pinyon-juniper treatments from Utah, 

 717 lb per acre were produced 7 years after a cabling and 

 seeding treatment in a precipitation year that should 

 have produced yields 132 percent of normal (Christensen 

 and others 1966). Thus, yields to be expected in a median 



REFERENCES 



Arnold, Joseph P.; Jameson, Donald A.; Reid, Elbert H. 

 1964. The pinyon-juniper type of Arizona: effects of 

 grazing, fire, and tree control. Prod. Res. Rep. 84. 

 Washington, DC: U.S. Department of Agriculture, 

 Forest Service. 28 p. 



Asay, K. H.; Knowles, R. P. 1985. Current status and 

 future of introduced wheatgrasses and wildryes for 

 rangeland improvement. In: Proceedings selected pa- 

 pers presented at the 38th annual meeting of the 

 Society for Range Management; 1985 February 11-15; 

 Salt Lake City, UT. Salt Lake City, UT: Society for 

 Range Management: 109-116. 



Christensen, Donald R.; Monsen, Stephen B.; Plummer, 

 A. Perry. 1966. Response of seeded and native plants 

 six and seven years after eradication of Utah juniper by 



10 



