Influence of Riparian Buffer Management On Soil Structural Properties and Hydraulic Conductivity.

Riparian buffer plant communities provide foliage and stems that increase surface roughness, slow runoff, and increase water infiltration. Buffer plant communities also provide a dense network of roots that contribute to soil carbon storage and bind riparian substrates to increase streambank resistance to erosion. Soil aggregate stability may influence hydraulic conductivity, soil sustainability, and soil and ecosystem functions. Understanding how these parameters vary spatially along a riparian buffer is important for its management. Three mowing regimes and one native grass transition regime were imposed along a riparian buffer zone surrounding a 650-m straightened agricultural tributary to Cane Run Creek in Fayette County KY. Baseline soil C was measured along a transect 2-m from the stream prior to treatment implementation. Soil aggregate size distribution, wet aggregate stability, and hydraulic conductivity were evaluated one year after regime establishment. Semivariogram analysis of C content indicated slight to moderate spatial dependency. No significant treatment effect on soil aggregate size distribution, wet aggregate stability, or hydraulic conductivity was seen after one year of treatment. Preliminary results indicate: a) mowing and native grass establishment procedures had no adverse effects on the evaluated parameters; b) one year of above-ground vegetation management was insufficient time to see significant changes in soil structure and hydraulic conductivity of this riparian buffer soil. Understanding how soil aggregate dynamics and hydraulic conductivity in riparian landscapes are influenced by aboveground management strategies and utilizing patterns of spatial processes to make vegetation management decisions will increase riparian buffer effectiveness at reducing agricultural nonpoint source pollution.