00949nas a2200289 4500008004500000245009900045210006900144100002200213700002000235700001800255700002000273700001600293700002200309700001800331700002500349700002500374700002000399700002300419700002500442700002200467700001500489700001600504700002300520700001900543700002400562856007300586 In Press eng d 00aHow low can you go? Widespread challenges in measuring low stream discharge and a path forward0 aHow low can you go Widespread challenges in measuring low stream1 aSeybold, Erin, C.1 aBergstrom, Anna1 aJones, Nathan1 aBurgin, Amy, J.1 aZipper, Sam1 aGodsey, Sarah, E.1 aDodds, W., K.1 aZimmer, Margaret, A.1 aShanafield, Margaret1 aDatry, Thibault1 aMazor, Raphael, D.1 aMessager, Mathis, L.1 aOlden, Julian, D.1 aWard, Adam1 aYu, Songyan1 aKaiser, Kendra, E.1 aShogren, Arial1 aWalker, Richard, H. uhttps://aslopubs.onlinelibrary.wiley.com/doi/full/10.1002/lol2.1035603030nas a2200229 4500008004100000245012900041210006900170300001100239490000800250520230600258653001802564653003102582653001002613653002302623100001902646700001602665700002302681700001102704700001702715700001802732856005002750 2019 eng d00aHow landscape heterogeneity governs stream water concentration-discharge behavior in carbonate terrains (Konza Prairie, USA)0 aHow landscape heterogeneity governs stream water concentrationdi a1189890 v5273 a

Mounting evidence suggests ecosystem changes that alter subsurface water fluxes and carbon dioxide concentrations in carbonate terrains may drive measurable changes in chemical weathering rates, stream water chemistry, and flow path evolution on human timescales. We test this idea by exploring if the encroachment of woody vegetation into grasslands in a carbonate terrain landscape at the Konza Prairie (KS, USA) has resulted in differences in landscape-stream connectivity and, thus, the behavior of stream water solutes. Woody encroachment (up to 60% cover) at Konza has been observed on watersheds, particularly those that experience a fire return interval of four years or greater. We focus on three headwater catchments (two grassland and one woody-encroached) and a downstream confluence, and analyze stream water discharge and chemistry (major anions, cations, and dissolved nutrients) measured from 2015 to 2016.

We observe that the woody-encroached watershed exhibits a greater area-normalized solute flux and greater degree of chemodynamic behavior for most geogenic species compared to the less encroached grassland watersheds. The downstream confluence exhibits the most chemostatic behavior for these same solutes compared to the low order watersheds. We interpret the chemodynamic behavior of the woody-encroached watersheds to arise from a greater diversity of flow paths and solute sources that contribute to this stream. End member mixing analysis (EMMA) supports this hypothesis but also indicates a possible “missing” end member which we interpret to be solutes likely derived from clay weathering along limestone-mudstone boundaries. We invoke differences in rooting systems between grass and woody species to explain the differences in flow paths and solute generation between these headwater sites given that they sit adjacent to each other, dissect the same nearly horizontal (dip 0.1–0.21°NW) lithologic units, and experience the same climate. If these processes hold true at other sites, then the globally observed encroachment of woody vegetation into grasslands may deepen flow paths and enhance chemical weathering fluxes from ecosystems, and over long-time periods alter the trajectory of soil development and landscape evolution.

10aCritical zone10aEnd member mixing analysis10aKarst10awoody encroachment1 aSullivan, P.L.1 aStops, M.W.1 aMacpherson, G., L.1 aLi, L.1 aHirmas, D.R.1 aDodds, W., K. uhttps://doi.org/10.1016/j.chemgeo.2018.12.00202269nas a2200205 4500008004100000245005300041210005300094300001300147490000700160520164700167653003501814653002201849653003001871653001901901653001801920653002501938100001801963700001601981856006601997 2008 eng d00aHeadwater influences on downstream water quality0 aHeadwater influences on downstream water quality a367 -3770 v413 a

We investigated the influence of riparian and whole watershed land use as a function of stream size on surface water chemistry and assessed regional variation in these relationships. Sixty-eight watersheds in four level III U.S. EPA ecoregions in eastern Kansas were selected as study sites. Riparian land cover and watershed land use were quantified for the entire watershed, and by Strahler order. Multiple regression analyses using riparian land cover classifications as independent variables explained among-site variation in water chemistry parameters, particularly total nitrogen (41%), nitrate (61%), and total phosphorus (63%) concentrations. Whole watershed land use explained slightly less variance, but riparian and whole watershed land use were so tightly correlated that it was difficult to separate their effects. Water chemistry parameters sampled in downstream reaches were most closely correlated with riparian land cover adjacent to the smallest (first-order) streams of watersheds or land use in the entire watershed, with riparian zones immediately upstream of sampling sites offering less explanatory power as stream size increased. Interestingly, headwater effects were evident even at times when these small streams were unlikely to be flowing. Relationships were similar among ecoregions, indicating that land use characteristics were most responsible for water quality variation among watersheds. These findings suggest that nonpoint pollution control strategies should consider the influence of small upland streams and protection of downstream riparian zones alone is not sufficient to protect water quality.

10ageographic information systems10aHeadwater streams10aNonpoint source pollution10aRiparian zones10awater quality10aWatershed management1 aDodds, W., K.1 aOakes, R.M. uhttps://link.springer.com/article/10.1007%2Fs00267-007-9033-y00435nam a2200097 4500008004100000245007000041210006700111260004000178100001800218856010100236 2008 eng d00aHumanity's Footprint: Momentum, Impact and our Global Environment0 aHumanitys Footprint Momentum Impact and our Global Environment aNew YorkbColumbia University Press1 aDodds, W., K. uhttp://lter.konza.ksu.edu/content/humanitys-footprint-momentum-impact-and-our-global-environment02395nas a2200133 4500008004100000245008300041210006900124300001100193490000700204520190300211100001602114700001802130856011302148 2005 eng d00aHarshness: characterization of intermittent stream habitat over space and time0 aHarshness characterization of intermittent stream habitat over s a13 -230 v563 aFrequently disturbed environments, such as intermittent streams, are ecologically useful for studying how disturbance characteristics (e.g. frequency, magnitude) affect community structure and succession. We developed a harshness index that quantifies ecologically pertinent spatial and temporal characteristics of prairie intermittent streams that may limit or reduce diversity and abundance to predict benthic macroinvertebrate assemblage characteristics. The index incorporates 11 variables that describe the hydrological regime (e.g. average flow, flow variability, drying and flooding) and distance to perennial surface water. We started with 27 variables, but removed 16 that did not increase the predictive value of the index. The relationships among index values and annual mean macroinvertebrate assemblage characteristics (taxonomic richness, diversity, evenness and abundance) were tested over two years using seven sites that represent a range of flow permanence (recent and historical), flood magnitude (recent and historical) and surface-water connectivity. Mean annual taxonomic richness was significantly related to the harshness index. Evenness and abundance were not related to harshness. Further analyses indicated that distance to the nearest permanent habitat was less important than annual or historical hydrological parameters, even though prior research had documented higher rates of colonisation at sites that were closer to nearest permanent habitat. Both annual factors that can alter abundance and colonisation immediately (e.g. floods, drought in each year) and historical factors (e.g. probability of drying, average length of dry period over decades) may influence assemblage characteristics. Historical factors may influence evolutionary adaptations of invertebrates and may predominate when relative disturbance rates are lower such as in years with less flooding.1 aFritz, K.M.1 aDodds, W., K. uhttp://lter.konza.ksu.edu/content/harshness-characterization-intermittent-stream-habitat-over-space-and-time00620nas a2200205 4500008004100000245003600041210003600077260003800113300001300151653002200164100001500186700002300201700002000224700001800244700002000262700001900282700001900301700002400320856007000344 1998 eng d00aHydrology and aquatic chemistry0 aHydrology and aquatic chemistry aNew YorkbOxford University Press a159 -17610atallgrass prairie1 aGray, L.J.1 aMacpherson, G., L.1 aKoelliker, J.K.1 aDodds, W., K.1 aKnapp, Alan, K.1 aBriggs, J., M.1 aHartnett, D.C.1 aCollins, Scott., L. uhttp://lter.konza.ksu.edu/content/hydrology-and-aquatic-chemistry