02026nas a2200169   4500008004100000245011800041210006900159300001500228490000800243520142900251100002101680700001901701700001701720700002001737700001701757856008201774       2010                        eng d00aThirteen decades of foliar isotopes indicate declining nitrogen availability in central North American grasslands0 aThirteen decades of foliar isotopes indicate declining nitrogen   a1135 -11450 v1873 a<p>&bull;Humans are increasing both the deposition of reactive nitrogen (N) and concentrations of atmospheric CO2 on Earth, but the combined effects on terrestrial ecosystems are not clear. In the absence of historical records, it is difficult to know if N availability is currently increasing or decreasing on regional scales. &bull;To determine the nature and timing of past changes in grassland ecosystem dynamics, we measured the composition of stable carbon (C) and N isotopes in leaf tissue from 545 herbarium specimens of 24 vascular plant species collected in Kansas, USA from 1876 to 2008. We also parameterized a simple model of the terrestrial N cycle coupled with a stable isotope simulator to constrain processes consistent with observed patterns. &bull;A prolonged decline in foliar N concentrations began in 1926, while a prolonged decline in foliar δ15N values began in 1940. Changes in the difference between foliar and atmospheric C isotopes reveal slightly increased photosynthetic water use efficiency since 1876. &bull;The declines in foliar N concentrations and foliar δ15N suggest declining N availability in these grasslands during the 20th century despite decades of anthropogenic N deposition. Our results are consistent with progressive-nitrogen-limitation-type hypotheses where declines in N availability are driven by increased ecosystem N storage as a result of increased atmospheric CO2.</p>1 aMcLauchlan, K.K.1 aFerguson, C.J.1 aWilson, I.E.1 aOcheltree, T.W.1 aCraine, J.M.  uhttps://nph.onlinelibrary.wiley.com/doi/full/10.1111/j.1469-8137.2010.03322.x00600nas a2200157   4500008004100000245009400041210006900135300001300204490000700217100001700224700002300241700002100264700002000285700002100305856011600326       2009                        eng d00aThe water budget, climate variability, and climate impacts assessment in Northeast Kansas0 awater budget climate variability and climate impacts assessment   a189 -1960 v321 aWilson, I.E.1 aHarrington, J., J.1 aMcLauchlan, K.K.1 aMartinson, E.J.1 aHutchinson, S.L.  uhttp://knz.lternet.edu/content/water-budget-climate-variability-and-climate-impacts-assessment-northeast-kansas