02937nas a2200229   4500008004100000245009500041210006900136300001200205490000700217520214000224653003102364653001602395653001302411653003702424653001902461653001902480653002502499653002202524100002002546700001702566856012402583       2002                        eng d00aMacroinvertebrate production and trophic structure in a tallgrass prairie headwater stream0 aMacroinvertebrate production and trophic structure in a tallgras  a97 -1130 v213 aResearch on North American prairie stream communities has lagged behind other regions. We examined the ecosystem significance of the macroinvertebrate community of riffle/run habitats in Kings Creek, a 2<sup>nd</sup>-order tallgrass prairie stream at Konza Prairie Biological Station (Kansas, USA), by estimating secondary production, benthic organic matter standing stocks, and resource consumption and egestion by functional groups. Annual mean standing stock macroinvertebrate biomass was 2.3 g ash-free dry mass (AFDM)/m<sup>2</sup>, annual production was 19.7 g AFDM m<sup>-2</sup> y<sup>-1</sup>, and the annual community production/biomass (P/B) ratio was 8.6. Macroinvertebrate production was higher than published estimates for forested streams of similar size, but much lower than that of a Sonoran desert stream. Distribution of production among functional groups was 30% for collector-gatherers, 9% for collector-filterers, 20% for scrapers, 23% for shredders, and 18% for predators, resembling estimates from some forested streams with the exception of higher scraper production. Although detritivorous groups were productive in this prairie stream, they appeared food limited. Consumption estimates indicated shredders and collector-gatherers annually ingested ∼80% and ∼240% of coarse particulate organic matter (CPOM) and fine particulate organic matter (FPOM) standing stocks, respectively. Thus, re-ingestion and/or diet shifts may be common, particularly among collector-gatherers, and the FPOM pool must turn over rapidly. Invertebrate predators also consumed a sizeable portion (∼52%) of prey, whereas scrapers (∼21%) and filterers (<1%) consumed relatively small portions of their respective resources, suggesting top-down influences on these groups. This study indicates that, during a period of relatively stable flow in this prairie stream, macroinvertebrate production and functional structure were roughly intermediate between North American forested and desert systems. Our results underscore the value of secondary production estimates for examining invertebrate communities in an ecosystem context10aAquatic macroinvertebrates10aEnergy flow10aFood web10aKonza Prairie Biological Station10aorganic matter10aPrairie stream10asecondary production10aTrophic structure1 aStagliano, D.M.1 aWhiles, M.R.  uhttp://lter.konza.ksu.edu/content/macroinvertebrate-production-and-trophic-structure-tallgrass-prairie-headwater-stream02549nas a2200325   4500008004100000245006100041210006100102300001300163490000600176520164900182653002001831653001401851653001901865653002001884653001101904653002201915100001801937700002201955700001801977700001301995700001702008700001502025700001702040700001802057700001602075700001502091700001702106700001702123856008302140       2000                        eng d00aQuantification of the nitrogen cycle in a prairie stream0 aQuantification of the nitrogen cycle in a prairie stream  a574 -5890 v33 aNitrogen (N) was added for 35 days in the form of 15NH4Cl to Kings Creek on Konza Prairie, Kansas. Standing stocks of N in key compartments (that is, nutrients, detritus, organisms) were quantified, and the amount of labeled N entering the compartments was analyzed. These data were used to calculate turnover and flux rates of N cycling through the food web, as well as nutrient transformation rates. Inorganic N pools turned over much more rapidly in the water column of this stream than in pelagic systems where comparable measurements have been made. As with other systems, the mass of ammonium was low but it was the key compartment mediating nutrient flux through the ecosystem, whereas dissolved organic N, the primary component of N flux through the system, is not actively cycled. Nitrification was also a significant flux of N in the stream, with rates in the water column and surface of benthos accounting for approximately 10% of the total ammonium uptake. Primary consumers assimilated 67% of the inorganic N that entered benthic algae and microbes. Predators acquired 23% of the N that consumers obtained. Invertebrate collectors, omnivorous crayfish (Orconectes spp.), and invertebrate shredders dominated the N flux associated with primary consumers. Mass balance calculations indicated that at least 23% of the 309 mg of 15N added during the 35 days of release was retained within the 210-m stream reach during the release. Overall, the rates of turnover of N in organisms and organic substrata were significantly greater when C:N was low. This ratio may be a surrogate for biological activity with regard to N flux in streams.10aaquatic insects10aC:N ratio10anitrogen cycle10anitrogen export10astream10aTrophic structure1 aDodds, W., K.1 aEvans-White, M.A.1 aGerlanc, N.M.1 aGray, L.1 aGudder, D.A.1 aKemp, M.J.1 aLo'pez, A.L.1 aStagliano, D.1 aStrauss, E.1 aTank, J.L.1 aWhiles, M.R.1 aWollheim, W.  uhttp://lter.konza.ksu.edu/content/quantification-nitrogen-cycle-prairie-stream02288nas a2200205   4500008004100000245008900041210006900130300001300199490000600212520162900218653001601847653000901863653001101872653001301883653001301896653002201909653002201931100001501953856011401968       1996                        eng d00aEffects of management practices on nematode community structure in tallgrass prairie0 aEffects of management practices on nematode community structure   a235 -2460 v33 aThe effects of burning, mowing, and nitrogen (N) and phosphorus (P) fertilization on the trophic structure of a tallgrass prairie nematode community were examined in a long-term field experiment established in 1986. Nematode densities and trophic composition were determined in October of 1987, 1989, and 1994 following 2, 4, and 9 years of treatment, respectively. Total populations of obligate herbivores tended to increase with annual burning and N fertilization but responses by individual taxa were relative to the structure and composition of vegetation as determined by management practice. In contrast, mowing resulted in consistent reductions in herbivore densities. The family Tylenchidae, with species classified as both root and fungal feeders, exhibited short-term decreases in numbers due to burning and long-term increases in numbers due to mowing. Treatment responses by this group were more consistent with the behavior of known fungal-feeding than root-feeding nematodes. Microbivore densities increased with burning and N fertilization, while numbers of omnivores and predators declined with chronic N additions. The effects of P fertilization on nematode population densities varied with management practice, primarily N fertilization. Canonical discriminant analysis differentiated trophic groups based on their responses to mowing and P-fertilization. Measurements of the trophic composition of the nematode community, particularly the relative abundance of individual herbivore taxa and the proportion of fungivores to microbivores, were good indicators of ecosystem responses to management practices.10adisturbance10afire10aMowing10aNematode10anitrogen10atallgrass prairie10aTrophic structure1 aTodd, T.C.  uhttp://lter.konza.ksu.edu/content/effects-management-practices-nematode-community-structure-tallgrass-prairie