@article {2447,
	title = {Holocene variability in hydrology, vegetation, fire, and eolian activity in the Nebraska Sand Hills, USA},
	journal = {The Holocene},
	volume = {23},
	year = {2013},
	month = {Jan-04-2013},
	pages = {515 - 527},
	abstract = {This study combined multiple aquatic and terrestrial proxies, including diatoms, pollen, grain size, and bulk-sediment chemistry to reconstruct the history
of three lake sites located in the central Sand Hills of Nebraska, USA. Long-term changes in effective moisture are evident at all sites, with significant
changes occurring at ~6000, ~4000, and ~ 2000 cal. yr BP. Both aquatic and terrestrial indicators suggest that effective moisture was low between
10,000 and ~6000 cal. yr BP, and that this time interval was the driest period of the Holocene. The dominance of benthic and tychoplanktic diatom taxa
indicates relatively shallow lake-level, high sand influx indicates moderately high eolian activity, and the pollen assemblage suggests xeric grasslands with
abundant mud flats. About 6000 cal. yr BP, all three sites experienced an increase in effective moisture. Lake-level rise is indicated by increases in planktic
and tychoplanktic diatoms relative to benthic taxa, while greater abundance of grass pollen and charcoal, and decreased eolian flux indicate stabilized
dunes with dense vegetation sufficient to fuel local fires. A significant hydrologic shift recorded at all sites occurred at ~4000 cal. yr BP. This event was
characterized by substantial lake-level rise, yet decreased grass cover and fire frequency, and increased eolian activity. Water-table rise may have been
caused by a combination of factors including: (1) formation of dune-dams that blocked old drainage channels, (2) reduced grass cover and hence reduced
evapotranspiration, and (3) changes in the frequency and duration of drought. The most likely cause(s) of the differential response of the terrestrial and
aquatic systems at this time is not clear, none-the-less the late Holocene was not nearly as dry as the interval prior to 6000 cal. yr BP. The last ~2000
yr were characterized by several short-term fluctuations in lake level, including an interval of drought between 950 and 750 cal. yr BP, coincident with
increased eolian activity during the latter part of the Medieval Climatic Anomaly.},
	keywords = {diatoms, drought, Holocene climate change, lakes, Nebraska Sand Hills, pollen},
	issn = {0959-6836},
	doi = {10.1177/0959683612463100},
	url = {http://journals.sagepub.com/doi/10.1177/0959683612463100},
	author = {Schmieder, Jens and Fritz, Sherilyn C and Grimm, Eric C and Jacobs, Kimberly C and Brown, Kendrick J and Swinehart, James B and Porter, Stephen C}
}
@article {2448,
	title = {A regional-scale climate reconstruction of the last 4000 years from lakes in the Nebraska Sand Hills, USA},
	journal = {Quaternary Science Reviews},
	volume = {30},
	year = {2011},
	month = {Jan-06-2011},
	pages = {1797 - 1812},
	abstract = {High-resolution paleohydrological reconstructions were carried out in five shallow lakes in the Nebraska Sand Hills across an eastewest transect in order to 1) determine whether long-term droughts of the past 4000 years were spatially and temporally coherent across the region, 2) distinguish local variation in
climate or hydrology from regional patterns of change, and 3) compare the paleolimnological results with the existing dune-inferred drought records. Diatom-inferred lake-level was reconstructed for all sites and compared with other regional records. Alterations between high and low lake-levels were
frequent during the past 4000 years, which suggests that shifts between dry and wet periods were prevalent across the Sand Hills. Extended multi-decadal to centennial-scale droughts were more common prior to 2000 years BP, while the last two millennia were hydrologically more variable and climate conditions alternated on shorter timescales. Despite some discrepancies among the five records, the paleohydrological reconstructions refine the Holocene drought history of the Nebraska Sand Hills, particularly between w2200 and 4000 cal a BP. Many of the observed drought events are contemporaneous with severe droughts documented at sites in the northern Great Plains and Rocky Mountains, lending support for the severity and regional significance of these events in western North America.},
	keywords = {diatoms, Droughts, Great Plains, Holocene, lakes, Nebraska Sand Hills, paleolimnology},
	issn = {0277-3791},
	doi = {10.1016/j.quascirev.2011.04.011},
	url = {http://linkinghub.elsevier.com/retrieve/pii/S0277379111001132http://api.elsevier.com/content/article/PII:S0277379111001132?httpAccept=text/xmlhttp://api.elsevier.com/content/article/PII:S0277379111001132?httpAccept=text/plain},
	author = {Schmieder, J. and Fritz, S.C. and Swinehart, J.B. and Shinneman, A.L.C. and Wolfe, A.P. and Miller, G. and Daniels, N. and Jacobs, K.C. and Grimm, E.C.}
}
