ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
Collection
Publisher
Years
  • 1
    facet.materialart.
    Unknown
    Towards More Realistic Projections of Soil Carbon Dynamics by Earth System Models (2015)
    Wiley
    Details
    Publication Date: 2015-12-20
    Description: Soil carbon (C) is a critical component of Earth system models (ESMs) and its diverse representations are a major source of the large spread across models in the terrestrial C sink from the 3 rd to 5 th assessment reports of the Intergovernmental Panel on Climate Change (IPCC). Improving soil C projections is of a high priority for Earth system modeling in the future IPCC and other assessments. To achieve this goal, we suggest that (1) model structures should reflect real-world processes, (2) parameters should be calibrated to match model outputs with observations, and (3) external forcing variables should accurately prescribe the environmental conditions that soils experience. Firstly, most soil C cycle models simulate C input from litter production and C release through decomposition. The latter process has traditionally been represented by 1 st -order decay functions, regulated primarily by temperature, moisture, litter quality, and soil texture. While this formulation well captures macroscopic SOC dynamics, better understanding is needed of their underlying mechanisms as related to microbial processes, depth-dependent environmental controls, and other processes that strongly affect soil C dynamics. Secondly, incomplete use of observations in model parameterization is a major cause of bias in soil C projections from ESMs. Optimal parameter calibration with both pool- and flux-based datasets through data assimilation is among the highest priorities for near-term research to reduce biases among ESMs. Thirdly, external variables are represented inconsistently among ESMs, leading to differences in modeled soil C dynamics. We recommend the implementation of traceability analyses to identify how external variables and model parameterizations influence SOC dynamics in different ESMs. Overall, projections of the terrestrial C sink can be substantially improved when reliable datasets are available to select the most representative model structure, constrain parameters, and prescribe forcing fields.
    Print ISSN: 0886-6236
    Electronic ISSN: 1944-9224
    Topics: Biology , Chemistry and Pharmacology , Geography , Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 2
    facet.materialart.
    Unknown
    Using ecosystem experiments to improve vegetation models (2015)
    Springer Nature
    Details
    Publication Date: 2015-05-22
    Description: The recent FACE model–data synthesis project used data from two FACE experiments to assess land ecosystem models. This Perspective details the 'assumption-centered' approach used to identify and evaluate the causes of model differences. Nature Climate Change 5 528 doi: 10.1038/nclimate2621
    Print ISSN: 1758-678X
    Electronic ISSN: 1758-6798
    Topics: Geosciences
    Published by Springer Nature
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 3
    facet.materialart.
    Unknown
    Nitrogen deposition and greenhouse gas emissions from grasslands: uncertainties and future directions (2015)
    Wiley
    Details
    Publication Date: 2015-12-11
    Description: Increases in atmospheric nitrogen deposition (N dep ) can strongly affect the greenhouse gas (GHG; CO 2 , CH 4 and N 2 O) sink capacity of grasslands as well as other terrestrial ecosystems. Robust predictions of the net GHG sink strength of grasslands depend on how experimental N loads compare to projected N dep rates, and how accurately the relationship between GHG fluxes and N dep is characterized. A literature review revealed that the vast majority of experimental N loads were higher than levels these ecosystems are predicted to experience in the future. Using a process-based biogeochemical model, we predicted that low levels of N dep either enhanced or reduced the net GHG sink strength of most grasslands, but as experimental N loads continued to increase, grasslands transitioned to a N saturation-decline stage, where the sensitivity of GHG exchange to further increases in N dep declined. Most published studies represented treatments well into the N saturation-decline stage. Our model results predict that the responses of GHG fluxes to N are highly nonlinear and that the N saturation thresholds for GHGs varied greatly among grasslands and with fire management. We predict that during the 21 st century some grasslands will be in the N limitation stage where others will transition into the N saturation-decline stage. The linear relationship between GHG sink strength and N load assumed by most studies can over- or underestimate predictions of the net GHG sink strength of grasslands depending on their N baseline status. The next generation of global change experiments should be designed at multiple N loads consistent with future N dep rates to improve our empirical understanding and predictive ability. This article is protected by copyright. All rights reserved.
    Print ISSN: 1354-1013
    Electronic ISSN: 1365-2486
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Geography
    Published by Wiley
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 4
    facet.materialart.
    Unknown
    Forests, Vol. 3, Pages 370-397: Harvesting Carbon from Eastern US Forests: Opportunities and Impacts of an Expanding Bioenergy Industry (2012)
    MDPI Publishing
    In: Forests
    Details
    Publication Date: 2012-06-20
    Description: Eastern forests of the US are valued both as a carbon sink and a wood resource. The amount of biomass that can be harvested sustainably from this biome for bioenergy without compromising the carbon sink is uncertain. Using past literature and previously validated models, we assessed four scenarios of biomass harvest in the eastern US: partial harvests of mixed hardwood forests, pine plantation management, short-rotation woody cropping systems, and forest residue removal. We also estimated the amount and location of abandoned agricultural lands in the eastern US that could be used for biomass production. Greater carbon storage was estimated to result from partial harvests and residue removals than from plantation management and short-rotation cropping. If woody feedstocks were cultivated with a combination of intensive management on abandoned lands and partial harvests of standing forest, we estimate that roughly 176 Tg biomass y−1 (~330,000 GWh or ~16 billion gallons of ethanol) could be produced sustainably from the temperate forest biome of the eastern US. This biomass could offset up to ~63 Tg C y−1 that are emitted from fossil fuels used for heat and power generation while maintaining a terrestrial C sink of ~8 Tg C y−1.
    Electronic ISSN: 1999-4907
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Published by MDPI Publishing
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 5
    facet.materialart.
    Unknown
    Impact of Precipitation Dynamics on Net Ecosystem Productivity (2011)
    Wiley
    Details
    Publication Date: 2011-11-23
    Description: Net ecosystem carbon dioxide (CO 2 ) productivity (NEP) was measured on shortgrass steppe (SGS) vegetation at the USDA Central Plains Experimental Range in northeastern Colorado from 2001 to 2003. Large year-to-year differences were observed in annual NEP, with 〉 95% of the net carbon uptake occurring during May and June. Low precipitation during the 2002 April to June time period greatly reduced annual net carbon uptake. Large precipitation events (〉 10 mm day −1 ) promoted carbon uptake, while small precipitation events (〈 10 mm day −1 ) enhanced heterotrophic respiration and resulted in a net loss of carbon from the system. Large precipitation event enhanced carbon uptake was attributed to increased soil water content (SWC), which promotes plant photosynthesis. The large precipitation events which occurred from July to October have lower increases in daytime net CO 2 uptake (NEP d ) due to the presence of low live plant biomass compared to earlier in the growing season. Live aboveground plant biomass (AGB), solar radiation, and SWC were the major variables that controlled NEP d , while AGB, SWC, and relative humidity control nighttime respiration losses (NEP n ). Aboveground plant biomass is the most important variable for controlling both NEP d and NEP n dynamics. These results suggest that the major factor controlling growing season NEP n is the amount of carbon fixed via photosynthesis during the day. Heterotrophic soil respiration is greatly enhanced for one to two days following rainfall events with daily rainfall events 〉 5 mm having a similar increase in respiration (〉 3.00 g m Cm −2 d −1 ). In addition, the size of the heterotrophic respiration pulse is independent of both the amount of time since the last rainfall event and the time of occurrence during the growing season.
    Print ISSN: 1354-1013
    Electronic ISSN: 1365-2486
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Geography
    Published by Wiley
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 6
    facet.materialart.
    Unknown
    CO2 emissions from crop residue-derived biofuels (2014)
    Springer Nature
    Details
    Publication Date: 2014-10-30
    Description: Nature Climate Change 4 932 doi: 10.1038/nclimate2403
    Print ISSN: 1758-678X
    Electronic ISSN: 1758-6798
    Topics: Geosciences
    Published by Springer Nature
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 7
    facet.materialart.
    Unknown
    Predicting long-term carbon sequestration in response to CO2 enrichment: How and why do current ecosystem models differ? (2015)
    Wiley
    Details
    Publication Date: 2015-03-22
    Description: Large uncertainty exists in model projections of the land carbon (C) sink response to increasing atmospheric CO 2 . Free-Air CO 2 Enrichment (FACE) experiments lasting a decade or more have investigated ecosystem responses to a step change in atmospheric CO 2 concentration. To interpret FACE results in the context of gradual increases in atmospheric CO 2 over decades to centuries, we used a suite of seven models to simulate the Duke and Oak Ridge FACE experiments extended for 300 years of CO 2 enrichment. We determine key modelling assumptions that drive divergent projections of terrestrial C uptake and evaluate whether these assumptions can be constrained by experimental evidence. All models simulated increased terrestrial C pools resulting from CO 2 enrichment, though there was substantial variability in quasi-equilibrium C sequestration and rates of change. In two of two models that assume that plant nitrogen (N) uptake is solely a function of soil N supply, the NPP response to elevated CO 2 became progressively N limited. In four of five models that assume that N uptake is a function of both soil N supply and plant N demand elevated CO 2 led to reduced ecosystem N losses and thus progressively relaxed nitrogen limitation. Many allocation assumptions resulted in increased wood allocation relative to leaves and roots which reduced the vegetation turnover rate and increased C sequestration. In addition, self-thinning assumptions had a substantial impact on C sequestration in two models. Accurate representation of N process dynamics (in particular N uptake), allocation, and forest self-thinning are key to minimising uncertainty in projections of future C sequestration in response to elevated atmospheric CO 2 .
    Print ISSN: 0886-6236
    Electronic ISSN: 1944-9224
    Topics: Biology , Chemistry and Pharmacology , Geography , Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 8
    facet.materialart.
    Unknown
    Land, Vol. 7, Pages 82: Model Based Regional Estimates of Soil Organic Carbon Sequestration and Greenhouse Gas Mitigation Potentials from Rice Croplands in Bangladesh (2018)
    MDPI
    In: Land
    Details
    Publication Date: 2018
    Description: Rice (Oryza sativa L.) is cultivated as a major crop in most Asian countries and its production is expected to increase to meet the demands of a growing population. This is expected to increase greenhouse gas (GHG) emissions from paddy rice ecosystems, unless mitigation measures are in place. It is therefore important to assess GHG mitigation potential whilst maintaining yield. Using the process-based ecosystem model DayCent, a spatial analysis was carried out in a rice harvested area in Bangladesh for the period 1996 to 2015, considering the impacts on soil organic carbon (SOC) sequestration, GHG emissions and yield under various mitigation options. An integrated management (IM, a best management practice) considering reduced water, tillage with residue management, reduced mineral nitrogen fertilizer and manure, led to a net offset by, on average, −2.43 t carbon dioxide equivalent (CO2-eq.) ha−1 year−1 (GHG removal) and a reduction in yield-scaled emissions intensity by −0.55 to −0.65 t CO2-eq. t−1 yield. Under integrated management, it is possible to increase SOC stocks on average by 1.7% per year in rice paddies in Bangladesh, which is nearly 4 times the rate of change targeted by the “4 per mille” initiative arising from the Paris Climate Agreement.
    Electronic ISSN: 2073-445X
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Published by MDPI
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 9
    facet.materialart.
    Unknown
    Land, Vol. 7, Pages 82: Model Based Regional Estimates of Soil Organic Carbon Sequestration and Greenhouse Gas Mitigation Potentials from Rice Croplands in Bangladesh (2018)
    MDPI
    In: Land
    Details
    Publication Date: 2018-07-06
    Description: Land, Vol. 7, Pages 82: Model Based Regional Estimates of Soil Organic Carbon Sequestration and Greenhouse Gas Mitigation Potentials from Rice Croplands in Bangladesh Land doi: 10.3390/land7030082 Authors: Khadiza Begum Matthias Kuhnert Jagadeesh Yeluripati Stephen Ogle William Parton Md Abdul Kader Pete Smith Rice (Oryza sativa L.) is cultivated as a major crop in most Asian countries and its production is expected to increase to meet the demands of a growing population. This is expected to increase greenhouse gas (GHG) emissions from paddy rice ecosystems, unless mitigation measures are in place. It is therefore important to assess GHG mitigation potential whilst maintaining yield. Using the process-based ecosystem model DayCent, a spatial analysis was carried out in a rice harvested area in Bangladesh for the period 1996 to 2015, considering the impacts on soil organic carbon (SOC) sequestration, GHG emissions and yield under various mitigation options. An integrated management (IM, a best management practice) considering reduced water, tillage with residue management, reduced mineral nitrogen fertilizer and manure, led to a net offset by, on average, −2.43 t carbon dioxide equivalent (CO2-eq.) ha−1 year−1 (GHG removal) and a reduction in yield-scaled emissions intensity by −0.55 to −0.65 t CO2-eq. t−1 yield. Under integrated management, it is possible to increase SOC stocks on average by 1.7% per year in rice paddies in Bangladesh, which is nearly 4 times the rate of change targeted by the “4 per mille” initiative arising from the Paris Climate Agreement.
    Electronic ISSN: 2073-445X
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Published by MDPI
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 10
    facet.materialart.
    Unknown
    Potential carbon dioxide emission reductions from avoided grassland conversion in the northern Great Plains (2016)
    Wiley
    In: Ecosphere
    Details
    Publication Date: 2016-12-22
    Description: Protection of lands threatened with conversion to agriculture can reduce carbon emissions. Until recently, most climate change mitigation incentive programs for avoided conversion have focused on forested ecosystems. We applied the Avoided Conversion of Grasslands and Shrublands v.1.0 (ACoGS) methodology now available through the American Carbon Registry to a threatened region of grasslands in the northern Great Plains. For all soil types across 14 counties in North and South Dakota, we used the DAYCENT model calibrated to the study area to quantify the difference in CO 2 and N 2 O emissions under a cropping and a protection scenario, and we used formulas in the ACoGS methodology to calculate CH 4 emissions from enteric fermentation under the protection scenario. We mapped the resulting GHG emissions across the entire project area. Emissions averaged 51.6 tCO 2 e/ha over 20 years, and with a 31% reduction for leakage and uncertainty from the ACoGS methodology, carbon offsets averaged 35.6 tCO 2 e/ha over 20 years. Protection of 10% of the 2.1 million unprotected ha in the project area with the highest emissions would reduce emissions by 11.7 million tCO 2 e over 20 years (11% of the total emissions from all unprotected grassland) and avoid a social cost of $430 million worth of CO 2 emissions. These results suggest that carbon offsets generated from avoided conversion of grasslands can meaningfully contribute to climate mitigation and grassland conservation objectives.
    Electronic ISSN: 2150-8925
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Published by Wiley on behalf of The Ecological Society of America (ESA).
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...