LB 15-140 - Biotic and abiotic influences on saturated hydraulic conductivity in the southern Great Plains

Saturated hydraulic conductivity (Ksat) is a key attribute in soil hydrology. Higher Ksat allows quicker downward movement of water through the soil profile. Ksat was primarily driven by soil texture, but the importance of vegetation is recognized more recently. The watershed in the climate transition is characterized by multiple land use and rapid change in vegetation, and its impact on Ksat has not been systematically studied. We hypothesized that wooded systems have a higher Ksat than herbaceous-dominated sites and tree basal area and species diversity increase Ksat. Four vegetation cover types (post oak (Quercus stellata), eastern redcedar (Juniperus virginiana), switchgrass (Panicum virgatum), and mixed species tallgrass prairie ) were selected based on the experimental watershed (n = 2) in the CTER Stillwater, Oklahoma. Twenty points were randomly selected within each watershed to quantify Ksat, plant diversity and richness in situ, and soil bulk density, soil texture, soil pH, organic matter, and ammonium were analyzed in the lab from collected soil samples. Ksat was significantly different across vegetation types (p =0.001), with no significant differences between the same cover type. Using Duncan grouping with alpha=0.05 each watershed type was shown to be different from one another. Of the four cover types, eastern redcedar watersheds had the highest Ksat (15.5cm/hr ) and switchgrass the lowest (6.91cm/hr ). Our results showed that multiple land use and rapid change in vegetation will alter Ksat and conversion from herbaceous-dominated sites to redcedar woodland generally increase Ksat.