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Hydrofluorocarbons (HFCs) are greenhouse gases with high global warming potentials that are mainly used in refrigeration and air conditioning. Historically, they were emitted only slowly from such systems and long term containment remains an important engineering and environmental issue. As part of their commitment under the Rio convention, nations are required to report annual calculated production and emissions of all greenhouse gases and the reports submitted by the European countries have been examined to determine the extent to which containment of HFCs (expressed as the rate of emission from the bank remaining in equipment) has changed with time. Although there is wide variation between countries, the annual...
Aiming at an improved understanding of the conditional nature of soil organic matter stability, we present an overview of (1) biotic strategies and (2) ecological processes by which decomposer organisms gain access to, or are prevented from metabolising soil organic resources. The biotic strategies discussed comprise well-known activities, such as the release of exo-enzymes, the mechanical crushing of organic residues, the bioturbation of soil mass, and the fixation of carbon in the living biomass. The ecological processes described have received less attention regarding their importance in prolonging the persistence of soil organic matter. Model calculations illustrate that cell energy demand forces micro-organisms...
Patterns and processes involved in litter breakdown on desert river floodplains are not well understood. We used leafpacks containing Fremont cottonwood (Populus deltoides subsp. wislizenii) leaf litter to investigate the roles of weather and microclimate, flooding (immersion), and macroinvertebrates on litter organic matter (OM) and nitrogen (N) loss on a floodplain in a cool-temperate semi-arid environment (Yampa River, northwestern Colorado, USA). Total mass of N in fresh autumn litter fell by 20% over winter and spring, but in most cases there was no further N loss prior to termination of the study after 653 days exposure, including up to 20 days immersion during the spring flood pulse. Final OM mass was 10?40%...
The amount of carbon plants allocate to mycorrhizal symbionts exceeds that emitted by human activity annually. Senescent ectomycorrhizal roots represent a large input of carbon into soils, but their fate remains unknown. Here, we present the surprising result that, despite much higher nitrogen concentrations, roots colonized by ectomycorrhizal (EM) fungi lost only one-third as much carbon as non-mycorrhizal roots after 2 years of decomposition in a piñon pine (Pinus edulis) woodland. Experimentally excluding live mycorrhizal hyphae from litter, we found that live mycorrhizal hyphae may alter nitrogen dynamics, but the afterlife (litter-mediated) effects of EM fungi outweigh the influences of live fungi on root...
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Decomposition of plant matter is one of the key processes affecting carbon cycling and storage in tidal wetlands. In this study, we evaluated the effects of factors related to climate change (temperature, inundation) and vegetation composition on rates of litter decay in seven tidal marsh sites along the Pacific coast. In 2014 we conducted manipulative experiments to test inundation effects on litter decay at Siletz Bay, OR and Petaluma marsh, CA. In 2015 we studied decay of litter in high and low elevation marshes at seven Pacific coast sites. These data support the following publication: Janousek, C.N., Buffington, K.J., Guntenspergen, G.R., Thorne, K.M., Dugger, B.D. and Takekawa, J.Y., 2017. Inundation, vegetation,...
Aiming at an improved understanding of the conditional nature of soil organic matter stability, we present an overview of (1) biotic strategies and (2) ecological processes by which decomposer organisms gain access to, or are prevented from metabolising soil organic resources. The biotic strategies discussed comprise well-known activities, such as the release of exo-enzymes, the mechanical crushing of organic residues, the bioturbation of soil mass, and the fixation of carbon in the living biomass. The ecological processes described have received less attention regarding their importance in prolonging the persistence of soil organic matter. Model calculations illustrate that cell energy demand forces micro-organisms...
We tested the hypothesis that decomposition in flood-inundated patches of riparian tree leaf litter results in higher plant-available nitrogen in underlying, nutrient-poor alluvium. We used leafpacks (n=56) containing cottonwood (Populus deltoides ssp. wislizenii) leaf litter to mimic natural accumulations of leaves in an experiment conducted on the Yampa River floodplain in semi-arid northwestern Colorado, USA. One-half of the leafpacks were set on the sandy alluvial surface, and one-half were buried 5 cm below the surface. The presence of NO3? and NH4+ presumed to result from a leafpack?s submergence during the predictable spring flood pulse was assessed using an ion-exchange resin bag (IER) placed beneath each...
Hydrofluorocarbons (HFCs) are greenhouse gases with high global warming potentials that are mainly used in refrigeration and air conditioning. Historically, they were emitted only slowly from such systems and long term containment remains an important engineering and environmental issue. As part of their commitment under the Rio convention, nations are required to report annual calculated production and emissions of all greenhouse gases and the reports submitted by the European countries have been examined to determine the extent to which containment of HFCs (expressed as the rate of emission from the bank remaining in equipment) has changed with time. Although there is wide variation between countries, the annual...
Hydrofluorocarbons (HFCs) are greenhouse gases with high global warming potentials that are mainly used in refrigeration and air conditioning. Historically, they were emitted only slowly from such systems and long term containment remains an important engineering and environmental issue. As part of their commitment under the Rio convention, nations are required to report annual calculated production and emissions of all greenhouse gases and the reports submitted by the European countries have been examined to determine the extent to which containment of HFCs (expressed as the rate of emission from the bank remaining in equipment) has changed with time. Although there is wide variation between countries, the annual...
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Herbivore alteration of litter inputs may change litter decomposition rates and influence ecosystem nutrient cycling. In a semiarid woodland at Sunset Crater National Monument, Arizona, long-term insect herbivore removal experiments and the presence of herbivore resistant and susceptible pinyon pines (Pinus edulis) have allowed characterization of the population- and community-level effects of herbivory. Here we report how these same two herbivores, the mesophyll-feeding scale insect Matsucoccus acalyptus and the stem-boring moth Dioryctria albovittella alter litter quality, dynamics, and decomposition in this ecosystem. We measured aboveground litterfall, litter chemical composition, and first-year litter decomposition...
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Invasion of the exotic annual grass Bromus tectorum into stands of the native perennial grass Hilaria jamesii significantly reduced the abundance of soil biota, especially microarthropods and nematodes. Effects of invasion on active and total bacterial and fungal biomass were variable, although populations generally increased after 50+ years of invasion. The invasion of Bromus also resulted in a decrease in richness and a species shift in plants, microarthropods, fungi, and nematodes. However, despite the depauperate soil fauna at the invaded sites, no effects were seen on cellulose decomposition rates, nitrogen mineralization rates, or vascular plant growth. When Hilaria was planted into soils from not-invaded,...
Although the link between the nitrogen (N): phosphorus (P) stoichiometry of biota and availability has received considerable attention in aquatic systems, there has been relatively little effort to compare the elemental composition of biota and supply in terrestrial habitats. In this study, I explored the effects of a prominent topo-edaphic gradient, from dry hilltop to wet slope-base, and native ungulates on N and P of soils, plants, and rates of in situ net mineralization in grasslands of Yellowstone National Park. Nitrogen and P measurements were made May?September, 2000, in paired, grazed and 38?42 year fenced, ungrazed grassland at five topographically variable sites. Similar to findings from other grassland...
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Plant-mediated processes are often important in determining carbon cycling and storage in ecosystems. With climate-induced changes in the environment, plant-associated processes may also shift. Salt marshes in particular are useful systems to investigate plant-mediated carbon cycling, as these systems experience both sea-level rise and increased carbon dioxide concentrations due to climate change, in addition to stochastically experiencing extreme drought and flood conditions. We measured biomass, soil, and gas carbon pools and the fluxes between those pools using a mesocosm approach in a salt marsh system, to investigate the response of plant-mediated carbon cycling to near-term climate change.
Traditional models of soil organic matter decomposition predict that soil carbon pools with high chemical stability and large physical structure are more resistant against degradation than chemically labile and fine-grained material. We investigated whether soil fauna, by its direct and indirect effects on carbon turnover, would reinforce or counteract this general trend. The effects of four major faunal groups on carbon pools of differing recalcitrance were studied in an extensive microcosm experiment. Ninty-six microcosms were inoculated with nematodes, enchytraeids, collembola, and lumbricids in three densities, including combinations of groups. Bare agricultural soil and soil covered with maize litter were used...
The distribution and turnover of plant litter contribute to soil structure, the availability of plant nutrients, and regional budgets of greenhouse gasses. Traditionally, studies of decomposition have focused on the upper soil profile. Other work has shown that temperature, precipitation, and soil texture are important determinates of patterns of decomposition. Since these factors all vary through a soil profile, it has been suggested that decomposition rates may vary with depth in a soil profile. In this work, we examine patterns of root decomposition through a shortgrass steppe soil profile. We buried fresh root litter from Bouteloua gracilis plants in litterbags at 10, 40, 70, and 100 cm. Litterbags were retrieved...
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Fluxes of dissolved organic matter (DOM) are an important vector for the movement of carbon (C) and nutrients both within and between ecosystems. However, although DOM fluxes from throughfall and through litterfall can be large, little is known about the fate of DOM leached from plant canopies, or from the litter layer into the soil horizon. In this study, our objectives were to determine the importance of plant-litter leachate as a vehicle for DOM movement, and to track DOM decomposition [including dissolve organic carbon (DOC) and dissolved organic nitrogen (DON) fractions], as well as DOM chemical and isotopic dynamics, during a long-term laboratory incubation experiment using fresh leaves and litter from several...
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This data table contains plant composition and marsh surface elevation data for 64 plots where Salicornia pacifica litter was buried at 7 sites in 2015. These data support the following publication: Janousek, C.N., Buffington, K.J., Guntenspergen, G.R. et al. Ecosystems (2017). doi:10.1007/s10021-017-0111-6. http://link.springer.com/article/10.1007/s10021-017-0111-6
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Coastal wetlands significantly contribute to global carbon storage potential. Sea-level rise and other climate change-induced disturbances threaten coastal wetland sustainability and carbon storage capacity. It is critical that we understand the mechanisms controlling wetland carbon loss so that we can predict and manage these resources in anticipation of climate change.
map background search result map search result map Soil Biota Can Change after Exotic Plant Invasion: Does This Affect Ecosystem Processes? Composition, Dynamics, and Fate of Leached Dissolved Organic Matter in Terrestrial Ecosystems: Results from a Decomposition Experiment Insect Herbivory Increases Litter Quality and Decomposition: An Extension of the Acceleration Hypothesis Organic matter decomposition along coastal wetland landscape gradient from tidal freshwater forested wetland to oligohaline marsh in Southeastern U.S.A. (2010-2011) Decomposition of plant litter in Pacific coast tidal marshes, 2014-2015 Vegetation Composition and Marsh Surface Elevation, 2015 Salt marsh carbon dynamics under altered hydrologic regimes and elevated CO2 conditions, Louisiana, USA (2014-2015) Insect Herbivory Increases Litter Quality and Decomposition: An Extension of the Acceleration Hypothesis Composition, Dynamics, and Fate of Leached Dissolved Organic Matter in Terrestrial Ecosystems: Results from a Decomposition Experiment Salt marsh carbon dynamics under altered hydrologic regimes and elevated CO2 conditions, Louisiana, USA (2014-2015) Soil Biota Can Change after Exotic Plant Invasion: Does This Affect Ecosystem Processes? Organic matter decomposition along coastal wetland landscape gradient from tidal freshwater forested wetland to oligohaline marsh in Southeastern U.S.A. (2010-2011) Decomposition of plant litter in Pacific coast tidal marshes, 2014-2015 Vegetation Composition and Marsh Surface Elevation, 2015