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Great Basin Naturalist

Abstract

On degraded subalpine range of the Wasatch Plateau, we examined the hypothesis that recovery of vegetation, as manifested by its composition and biomass yield, was related to soil phosphorus (P) and sulfur (S) status. We sampled 6 topographic locations to determine the relationship among composition and yield of grasses and forbs, litter cover, and soil characteristics including rock cover, organic carbon (Co), total N (Nt), available nitrogen (Nav), total phosphorus (Pt), organic P (Po), inorganic P (Pi), total potassium (K), total S (St), and element ratios. We also evaluated aspect effects. An alternative hypothesis was that productive potential was a function of depth of soil remaining after the period of destructive grazing. Differences among locations were significant for all vegetal attributes and for all soil characteristics except total K and Co. Aspect was significant only for forb yield and Pt. Regression coefficients for yield and percentage composition of grasses were always opposite in sign to those for forbs. Yield and composition of grasses and forbs as groups were oppositely and strongly related to soil element rations of Co/Pt, Nt/Po, Co/Pt, and Co/St but were not related to soil Pt or St. There was no clear support for acceptance of the hypothesis that soil P and/or S were major factors in recovery of this subalpine range after destructive grazing. Differences in regression coefficients and lower r-values among species within grass and forb groups, than for the groups themselves, to soil variables is a reflection of species individuality. This indicated a need to examine soil/vegetation relationships at the species level. Percentage compositions of grasses and forbs were oppositely related to the depth of A + B horizon, lending support to acceptance of the alternative hypothesis.

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