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Amino acids have been shown to be a potentially significant N source for the alpine sedge, Kobresia myosuroides. We hypothesised that freeze-thaw and dry-rewet events allow this plant species increased access to amino acids by disrupting microbial cells, which decreases the size of competing microbial populations, but increases soil amino acid concentrations. To test this hypothesis, we characterized freeze-thaw and dry-rewet events in the field and simulated them in laboratory experiments on plant-soil microcosms. In one experiment, 15N,13C-[2]-glycine was added to microcosms that had previously been subjected to a freeze-thaw or dry-rewet event, and isotopic concentrations in the plant and microbial fractions...
A positive role for biodiversity is assumed for managed ecosystems. We conducted a 12-year study of this sustainability principle, through separate manipulation of management intensity and crop diversity. The site was located in southwest Michigan, representative of rain-fed production, with high climate variability and well-drained soils. Provisioning services of grain and protein yield were monitored, simultaneous with supporting services of soil fertility, C and N, and regulating services associated with water quality (N-use efficiency and nitrate-N leached in gravimetric lysimeters). Surprisingly, a strong role for management was shown, and almost nil for crop diversity. Organic management (ORG) sustained soil...
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The exotic annual grass Bromus tectorum has replaced thousands of hectares of native perennial vegetation in semi-arid ecosystems of the western United States. Inorganic N availability and production were compared in soil from monodominant patches of Bromus tectorum, the perennial bunchgrass Elymus elymoides, and the shrub Artemisia tridentata, in Curlew Valley, a salt-desert shrub site in Northern Utah. Bromus-dominated soil had greater %N in the top 10 cm than Artemisia or Elymus-dominated soils. As determined by spring isotope-dilution assays, gross mineralization and nitrification rates were higher in Bromus-dominated than Artemisia-dominated soils, but gross rates of NH4+ and NO3- consumption were also higher....
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For his MS thesis, Brendan Rogers used the vegetation model MC1 to simulate vegetation dynamics, associated carbon and nitrogen cycle, water budget and wild fire impacts across the western 2/3 of the states of Oregon and Washington using climate input data from the the PRISM group (Chris Daly, OSU) at a 30arc second (800m) spatial grain. The model was run from 1895 to 2100 assuming that nitrogen demand from the plants was always met so that the nitrogen concentrations in various plant parts never dropped below their minimum reported values. A CO2 enhancement effect increased productivity and water use efficiency as the atmospheric CO2 concentration increased. Future climate change scenarios were generated through...
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For his MS thesis, Brendan Rogers used the vegetation model MC1 to simulate vegetation dynamics, associated carbon and nitrogen cycle, water budget and wild fire impacts across the western 2/3 of the states of Oregon and Washington using climate input data from the the PRISM group (Chris Daly, OSU) at a 30arc second (800m) spatial grain. The model was run from 1895 to 2100 assuming that nitrogen demand from the plants was always met so that the nitrogen concentrations in various plant parts never dropped below their minimum reported values. A CO2 enhancement effect increased productivity and water use efficiency as the atmospheric CO2 concentration increased. Future climate change scenarios were generated through...
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For his MS thesis, Brendan Rogers used the vegetation model MC1 to simulate vegetation dynamics, associated carbon and nitrogen cycle, water budget and wild fire impacts across the western 2/3 of the states of Oregon and Washington using climate input data from the the PRISM group (Chris Daly, OSU) at a 30arc second (800m) spatial grain. The model was run from 1895 to 2100 assuming that nitrogen demand from the plants was always met so that the nitrogen concentrations in various plant parts never dropped below their minimum reported values. A CO2 enhancement effect increased productivity and water use efficiency as the atmospheric CO2 concentration increased. Future climate change scenarios were generated through...
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For his MS thesis, Brendan Rogers used the vegetation model MC1 to simulate vegetation dynamics, associated carbon and nitrogen cycle, water budget and wild fire impacts across the western 2/3 of the states of Oregon and Washington using climate input data from the the PRISM group (Chris Daly, OSU) at a 30arc second (800m) spatial grain. The model was run from 1895 to 2100 assuming that nitrogen demand from the plants was always met so that the nitrogen concentrations in various plant parts never dropped below their minimum reported values. A CO2 enhancement effect increased productivity and water use efficiency as the atmospheric CO2 concentration increased. Future climate change scenarios were generated through...
Microbial activities drive the global nitrogen cycle, and in the past few years, our understanding of nitrogen cycling processes and the micro-organisms that mediate them has changed dramatically. During this time, the processes of anaerobic ammonium oxidation (anammox), and ammonia oxidation within the domain Archaea, have been recognized as two new links in the global nitrogen cycle. All available evidence indicates that these processes and organisms are critically important in the environment, and particularly in the ocean. Here we review what is currently known about the microbial ecology of anaerobic and archaeal ammonia oxidation, highlight relevant unknowns and discuss the implications of these discoveries...


    map background search result map search result map Inorganic N turnover and availability in annual- and perennial-dominated soils in a northern Utah shrub-steppe ecosystem Simulated potential historical (1971-2000) vegetation (mode) for the western 2/3 of Oregon and Washington using MC1 DGVM (dynamic global vegetation model) Simulated potential PNW vegetation for the Western 2/3 of Oregon and Washington under the Hadley CM3 general circulation model run with the A2 SRES emission scenario (2070-2099 mode) using the MC1 dynamic global vegetation model Simulated potential PNW vegetation the Western 2/3 of Oregon and Washington under CSIRO Mk3 general circulation model run with the A2 SRES emission scenario (2070-2099 mode) using the MC1 dynamic global vegetation model Simulated potential PNW vegetation the Western 2/3 of Oregon and Washington under MIROC 3.2 medres general circulation model run with the A2 SRES emission scenario (2070-2099 mode) using the MC1 dynamic global vegetation model Inorganic N turnover and availability in annual- and perennial-dominated soils in a northern Utah shrub-steppe ecosystem Simulated potential PNW vegetation for the Western 2/3 of Oregon and Washington under the Hadley CM3 general circulation model run with the A2 SRES emission scenario (2070-2099 mode) using the MC1 dynamic global vegetation model Simulated potential PNW vegetation the Western 2/3 of Oregon and Washington under CSIRO Mk3 general circulation model run with the A2 SRES emission scenario (2070-2099 mode) using the MC1 dynamic global vegetation model Simulated potential PNW vegetation the Western 2/3 of Oregon and Washington under MIROC 3.2 medres general circulation model run with the A2 SRES emission scenario (2070-2099 mode) using the MC1 dynamic global vegetation model Simulated potential historical (1971-2000) vegetation (mode) for the western 2/3 of Oregon and Washington using MC1 DGVM (dynamic global vegetation model)