00665nas a2200217   4500008004100000245006500041210006500106300001400171490000800185653003900193653001900232653001400251653000900265653001400274653001800288653002100306100002300327700002100350700002000371856005600391       2021                        eng d00aFire history as a key determinant of grassland soil CO2 flux0 aFire history as a key determinant of grassland soil CO2 flux  a579–5920 v46010aaboveground net primary production10acarbon cycling10aecosystem10afire10agrassland10asoil CO2 flux10asoil respiration1 aSlette, Ingrid, J.1 aLiebert, Alannah1 aKnapp, Alan, K.  uhttp://link.springer.com/10.1007/s11104-020-04781-002406nas a2200445   4500008004100000245018600041210006900227520093600296653002601232653001901258653002701277653001601304653002401320653001201344653001401356653001401370653002501384653001801409653002101427653002801448653004101476653002301517653001801540653001401558653003201572653002801604100001901632700001601651700001501667700002401682700001901706700001901725700001601744700002001760700001601780700001601796700001601812700001201828856012001840       2012                        eng d00aLong-term trends in ecological systems: a basis for understanding responses to global change. USDA Agriculture Research Service Publication, Technical Bulletin 1931. Washington, D.C0 aLongterm trends in ecological systems a basis for understanding 3 a<p>Peters, D.P.C., C.M. Laney, A.E. Lugo, et al. 2013. Long-Term Trends in Ecological Systems: A Basis for Understanding Responses to Global Change. U.S. Department of Agriculture, Technical Bulletin Number 1931. The EcoTrends Editorial Committee sorted through vast amounts of historical and ongoing data from 50 ecological sites in the continental United States including Alaska, several islands, and Antarctica to present in a logical format the variables commonly collected. This report presents a subset of data and variables from these sites and illustrates through detailed examples the value of comparing longterm data from different ecosystem types. This work provides cross-site comparisons of ecological responses to global change drivers, as well as longterm trends in global change drivers and responses at site and continental scales. Site descriptions and detailed data also are provided in the appendix section.</p>10aatmospheric chemistry10aClimate change10across-site comparisons10adisturbance10aecological response10aecology10aecosystem10aEcoTrends10aexperimental forests10aglobal change10ahuman demography10ahuman population growth10aLong Term Ecological Research (LTER)10along-term datasets10aPrecipitation10arangeland10arangeland research stations10asurface water chemistry1 aPeters, D.P.C.1 aLaney, C.M.1 aLugo, A.E.1 aCollins, Scott., L.1 aDriscoll, C.T.1 aGroffman, P.M.1 aGrove, J.M.1 aKnapp, Alan, K.1 aKratz, T.K.1 aOhman, M.D.1 aWaide, R.B.1 aYao, J.  uhttp://knz.lternet.edu/content/long-term-trends-ecological-systems-basis-understanding-responses-global-change-usda02995nas a2200193   4500008004100000245011700041210006900158260004300227490001400270520238200284653001402666653001502680653001402695653001102709653001102720100001602731700001802747856003602765       2010                        eng d00aEcosystem Processes of Prairie Streams and the Impact of Anthropogenic Alteration on Stream Ecological Integrity0 aEcosystem Processes of Prairie Streams and the Impact of Anthrop  aManhattan, KSbKansas State University0 vMS Thesis3 a<p>orth America has lost more than 95% of the original tallgrass prairie because of heavy land conversion, making prairie streams some of the most endangered habitats in North America. In order to effectively manage aquatic systems and improve biotic integrity of prairie streams research is needed that assesses the ecosystem characteristics of natural systems and evaluates the influence of anthropogenic alteration. We described the ecosystem characteristics of six ephemeral headwater streams draining tallgrass prairie within the Osage Plains of southwest Missouri. NO-3-N among all sites ranged from 1.56-91.36 μg L-1, NH+4-N ranged from 5.27-228.23 μg L-1, soluble reactive phosphorus ranged from below detection (1.0 μg L-1) to 41.22 μg L-1, TN ranged from 113.82-882.89 μg L-1, and TP ranged from 8.18-158.5 μg L-1during baseflow conditions. TN:TP molar ratios ranged from 22:1 to 53:1 indicating possible P was limiting relative to N in some streams. TSS during baseflow conditions ranged from 0.27-31.80 mg L-1. Autotrophic and heterotrophic comparisons of our study sites and reference sites classified our study streams as oligo-, meso-, and eu-autotrophic (N= 1, 4, and 1, respectively) and oligo-, meso-, and eu-heterotrophic (N= 4, 1, and 1, respectively). This study suggests that good water quality and moderate heterotrophic condition, with greater GPP resulting from an open canopy, are common conditions of tallgrass prairie streams. We also investigated interactions between land use/land cover, discharge rate, hydrologic alteration, and in-stream total suspended solids concentration in 23 Kansas- Missouri streams. Most streams had break points in the TSS loading rates at discharge rates exceeded &lt;25% of days. Our estimates showed that 88% of the total annual TSS load occurred during the 11% of days with the greatest discharge rates. Buffered streams with greater percentages of grass and/or forest riparian areas had lower breakpoint values (indicating greater discharge rates were required to transport solid particles) and lower regression intercepts, which correlated to lesser TSS concentrations relative to unbuffered streams during high discharge days. In addition, grass buffered streams had smaller flood peaks and slower rise rates and forest buffered streams had less frequent floods, which lead to less total TSS transport.</p>10aecosystem10ametabolism10anutrients10asolids10astream1 aWinders, K.1 aDodds, W., K.  uhttp://hdl.handle.net/2097/684902300nas a2200181   4500008004100000245009500041210006900136300001300205490000700218520168400225653001601909653001401925653001801939653001801957100001801975700001501993856011002008       2007                        eng d00aExpanding the concept of trophic state in aquatic ecosystems: It's not just the autotrophs0 aExpanding the concept of trophic state in aquatic ecosystems Its  a427 -4390 v693 a“Trophic state” is often used to classify aquatic ecosystems according to biotic productivity. Primary productivity (or a surrogate for it) has always been used as the metric of trophic state. We make the case here that both primary production and key heterotrophic processes are needed to evaluate trophic state. Defined as the relative flux rate of carbon (C) into the food web, trophic state is a fundamental property that is intimately related to both ecosystem structure and how humans influence water quality. Rates of heterotrophic activity can exceed primary production in many aquatic ecosystems including oceans, lakes, and streams. A comprehensive definition of trophic state with respect to aquatic food webs requires accounting for both the oxidation of organic C (respiration) and photosynthetic fixation of inorganic C (primary production). This inclusive definition is required because food webs can be fueled in part by allochthonous C. We propose autotrophic and heterotrophic states be defined by rates of photosynthetic and respiratory C fluxes respectively, and both be used to characterize ecosystems. Cumulative frequency distributions of both can be developed for minimally impacted aquatic systems as a baseline against which to compare human-influenced sites as well as for describing the range of conditions that aquatic organisms have experienced in their recent evolutionary history. Subsidies of organic C and inorganic nutrients to aquatic ecosystems influence heterotrophic state, so characterizing the base of the food web necessitates a stoichiometric view of supply rates, use efficiencies, and recycling of inorganic and organic materials.10aautotrophic10aecosystem10aheterotrophic10aTrophic state1 aDodds, W., K.1 aCole, J.J.  uhttp://knz.lternet.edu/content/expanding-concept-trophic-state-aquatic-ecosystems-its-not-just-autotrophs02258nas a2200361   4500008004100000245009100041210006900132300001300201490000700214520122700221653001401448653001401462653001801476653001801494653001801512100001801530700001501548700001901563700001901582700001401601700001501615700001401630700001701644700002001661700001201681700001801693700001501711700001401726700001601740700001701756700001401773856010901787       2003                        eng d00aAssessing the response of terrestrial ecosystems to potential changes in precipitation0 aAssessing the response of terrestrial ecosystems to potential ch  a941 -9520 v533 aChanges in Earth's surface temperatures caused by anthropogenic emissions of greenhouse gases are expected to affect global and regional precipitation regimes. Interactions between changing precipitation regimes and other aspects of global change are likely to affect natural and managed terrestrial ecosystems as well as human society. Although much recent research has focused on assessing the responses of terrestrial ecosystems to rising carbon dioxide or temperature, relatively little research has focused on understanding how ecosystems respond to changes in precipitation regimes. Here we review predicted changes in global and regional precipitation regimes, outline the consequences of precipitation change for natural ecosystems and human activities, and discuss approaches to improving understanding of ecosystem responses to changing precipitation. Further, we introduce the Precipitation and Ecosystem Change Research Network (PrecipNet), a new interdisciplinary research network assembled to encourage and foster communication and collaboration across research groups with common interests in the impacts of global change on precipitation regimes, ecosystem structure and function, and the human enterprise.10aCommunity10aecosystem10aglobal change10aPrecipitation10asoil moisture1 aWeltzin, J.F.1 aLoik, M.E.1 aSchwinning, S.1 aWilliams, D.G.1 aFay, P.A.1 aHaddad, B.1 aHarte, J.1 aHuxman, T.E.1 aKnapp, Alan, K.1 aLin, G.1 aPockman, W.T.1 aShaw, M.R.1 aSmall, E.1 aSmith, M.D.1 aTissue, D.T.1 aZak, J.C.  uhttp://knz.lternet.edu/content/assessing-response-terrestrial-ecosystems-potential-changes-precipitation02696nas a2200205   4500008004100000245009500041210006900136300001500205490000700220520202100227653001402248653001302262653001402275653001402289100001502303700001802318700002002336700001702356856011702373       2002                        eng d00aChanges in ecosystem structure and function along a chronosequence of  restored grasslands0 aChanges in ecosystem structure and function along a chronosequen  a1688 -17010 v123 aChanges in aboveground vegetation, roots, and soil characteristics were examined from a 12-yr chronosequence of formerly cultivated fields restored to native C4 grasses through the Conservation Reserve Program (CRP). Following 6–8 yr in the CRP, the native grasses dominated vegetation composition, and the presence of forbs was negligible. Productivity of the restored grasslands did not exhibit any directional changes with the number of years in the CRP, and productivity was generally higher than native prairie in this region. Over time, the restored grasslands accumulated root biomass of decreasing quality as indicated by increasing root biomass and C:N ratio of roots along the 12-yr chronosequence. Root biomass, root C:N ratio, C storage in roots, and N storage in roots of restored grasslands approached that of native tallgrass prairie within the 12 yr of restoration. Establishment of the perennial vegetation also affected soil physical, chemical, and biological characteristics. Soil bulk density in the surface 10 cm decreased with time since restoration. Total C, microbial biomass C, and C mineralization rates increased as a function of time since restoration. The greatest change in total C occurred in the surface 5 cm, where total C was 26% greater in 12- vs. 2-yr restored grasslands. Extractable soil nitrate and soil N transformations (i.e., net N mineralization rates and net nitrification rates) declined over the restoration chronosequence, but these values were not representative of steady-state conditions due to the high variability in these measures among the native prairies. Although complete restoration of ecosystem structure and function was not the primary intention of the CRP, this study demonstrates that establishment of the matrix vegetation (i.e., native C4 grasses) drives ecosystem processes in the trajectory of the original system. Moreover, restoration may hasten the recovery of soil C pools relative to formerly cultivated systems undergoing natural succession.10aecosystem10afunction10agrassland10astructure1 aBaer, S.G.1 aKitchen, D.J.1 aBlair, John, M.1 aRice, C., W.  uhttp://knz.lternet.edu/content/changes-ecosystem-structure-and-function-along-chronosequence-restored-grasslands