Playas are those big ponds you see dotting across the High Plains. They provide habitat for amphibians and points for aquifer recharge. A study from Oklahoma State University suggests the Federal Conservation Reserve Program does have a positive impact on the health of the playas, but does not restore them reported The Environmental Monitor.
“It preserves the wetland, but the state that it preserves the wetland in is not its natural state,” says Dale Daniel. “It’s not functioning as it’s supposed to be, but you’re not losing it.” Daniel is a doctoral student at the OSU.
Daniel and his collaborators set out to calculate the volume lost to sedimentation in 258 playas across Nebraska, Colorado, Kansas, Oklahoma, New Mexico and Texas.
The crews surveyed wetlands in watersheds dominated by cropped land, native shortgrass prairie and land in the Conservation Reserve Program. Using a Trimble handheld GPS unit, the crew walked the perimeter of each playa to map it, and then measured the elevation to calculate the volume. By measuring the depth of sediment in the center of the wetland, they could calculate the volume lost to eroded soil.
The results show that the wetlands in watersheds under the Conservation Reserve Program are indeed in better shape than those in cropped watersheds, showing 57 percent less volume loss overall to sedimentation. However, the volume loss for wetlands in conservation land watersheds was 76 percent higher than the loss in wetlands in undisturbed native grassland watersheds.
That suggests that while the Conservation Reserve Program has stopped sedimentation in wetlands within its lands, it can’t undo the damage that occurred before the program went into place. In addition, the program replants cropland in native grasses, but not necessarily the short-grass prairie species that would be a more natural option. The longer mixed grasses appear to disrupt runoff into the playas, leading the wetlands to be inundated less often.
The High Plains is one of the most highly cultivated regions of the world.
More information about this study is available from The Environmental Monitor.