Sand dune stabilization reduces infiltration and soil moisture: a case study from the northern Great Plains



Throughout the northern Great Plains of North America, there are large tracts of vegetation-stabilized aeolian dune fields; some have transformed from desert-like conditions to grassland only within the last 200 years. Here, we examine how this transformation has affected vadose zone hydrology by comparing infiltration and soil moisture on stabilized and active dunes at a dune field in Saskatchewan, Canada. At one active and one stabilized dune, we measured soil moisture dynamics throughout the 2010 growing season with time-domain reflectometry sensors installed at four depths down to 200 cm below the surface. We also acquired soil samples from two active and two stabilized dunes ten times throughout the 2010 growing season to measure soil moisture dynamics down to 500 cm below the surface. Results indicate that while soil moisture was elevated at 25 cm depth in the stabilized dunes during the 2010 growing season, below that level soil, moisture was significantly lower than the active dunes and also more variable down to 500 cm. A comparison of surface hydraulic conductivity between one active dune and one stabilized dune showed that it was more than one order of magnitude greater at the former, presumably due to the elevated levels of silt, clay, and organics at the surface of the stabilized dune, which reduce the infiltration rate. Overall, we interpret the main difference in soil moisture dynamics to be caused by the presence of transpiring vegetation, as well as changes in soil properties attributed to the establishment of vegetation. Therefore, the results of this study suggest that during dune stabilization, the establishment of vegetation reduces profile soil moisture recharge. Copyright © 2013 John Wiley & Sons, Ltd.