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United States Department of Agriculture

Agricultural Research Service

Title: Gradient Analysis of Environmental and Hydrologic Variables As Related to Rangeland Vegetation

Authors
item Spaeth, Kenneth - SCS
item PIERSON, FREDERICK
item WELTZ, MARK
item Awang, J - UNIVERSITY OF IDAHO

Submitted to: Transactions of the ASAE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 1, 1996
Publication Date: N/A

Interpretive Summary: Rangeland plant communities and the hydrologic cycle associated with them are affected by many interacting biotic (living) and abiotic (nonliving) components. A rotating boom rainfall simulator was used to apply rainfall in three applications (dry run, wet run, and very wet run) to paired 3.05 x 10.7 m runoff plots. Rainfall simulations were conducted in 10 states which represented tall-grass, mixed-grass, short- grass and sagebrush communities. Effective terminal infiltration rate was highest among the sagebrush communities. Comparisons of infiltration equations for the pooled data set resulted in poor to fair models. Infiltration models which represented specific rangeland community types (short-grass, mixed-grass, tall-grass, and sagebrush- grass) were significantly better. The use of plant species which were common to the respective sites also improved infiltration prediction. For example, in the tall-grass prairie, specific grass, a common tall gras species resulted in better infiltration models compared to not including plant species. Although this study did not identify the model enhancing characteristics of indiangrass, we hypothesize that above ground biomass is related to subsoil rooting characteristics and other soil enhancing properties which are difficult to measure.

Technical Abstract: Rangeland plant communities and the hydrologic cycle associated with them are multivariate in nature and are affected by many interacting biotic and abiotic components. A rotating boom rainfall simulator was used to apply rainfall in three applications (dry run, wet run, and very wet run) to paired 3.05 x 10.7 m runoff plots. Representative plant community types were tall-grass, mixed-grass, short-grass prairie, and sagebrush steppe. Indirect gradient analysis was used to summarize relationships between rangeland plant communities and environmental factors. Effective terminal infiltration rate (fe) was highest in sagebrush communities. Comparisons of infiltration equations for the pooled data set (144 runoff plots, 24 sites, 10 states) resulted in fair models (R2=0.45). Infiltration models which represented specific rangeland community types (short-grass, mixed-grass, tall-grass, and sagebrush-grass) all had R2 values above 0.71. The use of endemic plant species in the model building process also improved fe rates. For example, in the tall-grass prairie, the inclusion of above ground indiangrass (Sorghastrum nutans) biomass, an endemic grass species, and other plants as independent variables increased model coefficients of determination from 0.71 to 0.83.

Last Modified: 9/10/2014
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