Holocene records of environmental change in High Plains playa wetlands, Kansas, US

Abstract

Holocene environmental change is poorly characterized throughout much of the High Plains. Playa wetlands are sites with appreciable potential for reconstructing environmental change because of their environmental sensitivity. Radiocarbon, litho- and magneto-stratigraphic, and stable carbon isotope (δ13C) data for four playas on the Kansas High Plains indicate significant change occurred throughout the Holocene, which had profound impacts on playa ecosystem functions (e.g. groundwater recharge, surface water storage, and habitat). Minimum δ13C values and buried soils observed during the Pleistocene–Holocene transition suggest sufficient moisture to support vegetative cover and promote pedogenesis. Low magnetic susceptibility, rapid increase in δ13C, and weak pedogenic alteration in overlying deposits suggest early Holocene aridity with increased landscape instability and sediment deposition. Early to middle Holocene stratigraphy transitioned from loess with little pedogenic modification into overlying buried soils; δ13C values indicate playa vegetation was composed of as much as 90% C4plants. Maximum magnetic susceptibility and buried soils in late Holocene deposits indicate sufficient moisture to support vegetative cover and promote pedogenesis. The Pleistocene–Holocene transition was a cool, moist period in which sediment accumulation rates in playas were low and ecosystem functions were optimal. Throughout much of the early to early–middle Holocene, playas were subaerially exposed, sediment accumulation outpaced soil formation, and ecosystem functions were inhibited by lack of moisture. From the middle to late Holocene, the climate returned to more mesic conditions, sediment accumulation and soil formation were in near equilibrium, and the ability of playas to perform ecosystem functions increased.