Submitted to: Society for Range Management Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 9/30/2006
Publication Date: 2/9/2007
Citation: Hendrickson, J.R., Johnson, D.A. 2007. Methods to estimate peak herbaceous biomass in a sagebrush steppe. Society for Range Management Meeting Abstracts. Interpretive Summary:
Technical Abstract: Understanding herbaceous biomass dynamics in sagebrush steppe rangelands is important in managing rangelands for both forage and wildlife production. We evaluated herbaceous biomass dynamics on a 16 ha site on the U.S. Sheep Experiment Station in Dubois, Idaho that was exclosed from livestock grazing in 1996. Herbaceous biomass (grass and forb) was clipped to ground level in five 0.5-m2 quadrats every two weeks from late April to late June and monthly from July through October from 1997 to 1999. Biomass was sorted into grass and forb components in the field and then refrigerated at the laboratory. Biomass was then separated into live and dead components. Live biomass accumulation, peak and senescence were estimated by using both PROC NLIN and PROC RSREG in SAS. PROC NLIN determined the timing of peak biomass and developed separate linear regression equations for biomass accumulation and senescence while PROC RSREG used a quadratic regression equation for the entire season while still providing an estimate of amount and timing of peak biomass. Peak biomass for each component peaked at a different time in each year. R2 values were higher for grass and total biomass than for forb biomass. The PROC NLIN generally had a higher R2 value and estimated values corresponded more closely to field data than did PROC RSREG except for the forb component in 1998. The use of PROC NLIN provided a more accurate estimation of timing and amount of peak biomass than use of a quadratic equation.