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Title: Microchannels affect runoff and sediment yield from a shortgrass prairie

Author
item KOLER, SELINA - COLORADO STATE UNIVERSITY
item FRASIER, GARY - RETIRED ARS SCI-COLLABORA
item TRILICA, M - COLORADO STATE UNIVERSITY
item REEDER, JEAN - RETIRED ARS SCI-COLLABORA

Submitted to: Rangeland Ecology and Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/27/2008
Publication Date: 9/3/2008
Citation: Koler, S., Frasier, G.W., Trilica, M.J., Reeder, J.D. 2008. Microchannels affect runoff and sediment yield from a shortgrass prairie. Rangeland Ecology and Management 61(5):521-528.

Interpretive Summary: Runoff and erosion from rangelands is a complex process that involves interactions among landform, soils, and vegetation. Additional information is needed to better understand the effects of micro-topography and vegetation characteristics on surface runoff and sediment transport. Rainfall simulations were used to quantify the effects of microchannels and soil removal on runoff and sediment loss under good and fair range conditions on a shortgrass prairie in Northern Colorado. Microchannels increased total runoff but reduced the sediment yield per unit of runoff compared with plots where incised channels were not present. Greater runoff occurred from fair range condition plots dominated by buffalo grass, whereas sediment yield was greater from good condition plots dominated by blue grama and western wheatgrass. The study gives further insight as to how rangeland vegetation composition, growth form, and surface microtopography all affect runoff and sediment transport processes.

Technical Abstract: Runoff and sediment yield from rangelands are extremely important variables that affect productivity, but are difficult to quantify. Studies have been conducted to assess erosion on rangelands, but very little has been done to determine if microchannels (rills) affect runoff and sediment yield. Rainfall simulations were used to quantify the effects of microchannels on runoff and sediment loss on a shortgrass prairie with 2 types of range conditions (good and fair). Natural flow paths within plots in the 2 range conditions were defined and then enhanced with an ellipse-shaped hoe to create microchannels. Soil from plots was removed at 2 rates (11.2 and 22.4 t ha-1) to create 3 soil surface configurations. Soil was removed by vacuuming to create either a single microchannel, or multiple microchannels down the plot, and the third treatment was uniform soil removal over the entire plot (sheet). Results showed significantly greater total runoff from both single and multiple microchannel treatments compared with sheet soil removal. The microchannels resulted in significantly less sediment yield per unit of runoff compared with the sheet soil removal treatment. Both runoff and sediment yield were affected by range condition. Plots that were in fair range condition, dominated by buffalo grass (Buchloe dactyloides (Nutt.) Engleman), had a greater amount of total runoff but less sediment yield than plots in good range condition that were dominated by blue grama (Bouteloua gracilis (H.B.K.) Lag. ex Stued.). The dense buffalo grass sod protected the soil surface from erosion, but water flowed freely across the sod. This study has provided a greater understanding of how microchannels affect runoff and sediment yield under different rangeland conditions, and has illustrated how plant species composition and soil surface features relate to several hydrologic functions.