Download or read book Analysis of Carbon Dioxide and Methane Cycling in Forest Soils Using Stable Carbon Isotopes written by and published by . This book was released on 2008 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Understanding the role of forests in the cycling of methane (CH4) and carbon dioxide (CO2) is of importance to the elucidation of global greenhouse gas budgets. Previous studies have shown aerated forests soils to be net sinks of atmospheric CH4 and sources of carbon dioxide. While much research has focused on the role of forest soils as CO2 sources and CH4 sinks, few studies have utilized 13C-isotope studies to clarify the nature of subsurface CO2 production and CH4 consumption. The present study, carried out in 3 temperate forest environments on Vancouver Island during 2006 and 2007, and a boreal forest in northern Quebec in 2005, is intended to address this paucity of information. The isotope and concentration data corroborates previous studies in suggesting that both temperate and boreal forest environments act as net CH4 sinks and CO2 sources. No clear evidence of methanogenesis is apparent in either Vancouver Island or northern Quebec, where the isotopic composition of subsurface CH4 is influenced by diffusive and biological fractionation. Near-surface photosynthetic uptake may have a strong influence on the isotopic composition of soil CO2 and the resultant fluxes, acting to reduce apparent fluxes due to CO2 consumption. Intra-site variability of CH4 and CO2 fluxes indicates that the use of two static chambers in a single site, while sufficient for the confirmation of gas uptake or emission, may be less adequate in the determination of actual rates of efflux/influx. Future studies should address this by either sampling a larger area, installing a greater number of chambers, or by utilizing entirely different methods, such as the use of eddy covariance techniques.
Download or read book Analysis of Carbon Dioxide and Methane Cycling in Forest Soils Using Stable Carbon Isotopes written by Kern Young Lee and published by . This book was released on 2008 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Understanding the role of forests in the cycling of methane (CH4) and carbon dioxide (CO2) is of importance to the elucidation of global greenhouse gas budgets. Previous studies have shown aerated forests soils to be net sinks of atmospheric CH4 and sources of carbon dioxide. While much research has focused on the role of forest soils as CO2 sources and CH4 sinks, few studies have utilized 13C-isotope studies to clarify the nature of subsurface CO2 production and CH4 consumption. The present study, carried out in 3 temperate forest environments on Vancouver Island during 2006 and 2007, and a boreal forest in northern Quebec in 2005, is intended to address this paucity of information. The isotope and concentration data corroborates previous studies in suggesting that both temperate and boreal forest environments act as net CH4 sinks and CO2 sources. No clear evidence of methanogenesis is apparent in either Vancouver Island or northern Quebec, where the isotopic composition of subsurface CH4 is influenced by diffusive and biological fractionation. Near-surface photosynthetic uptake may have a strong influence on the isotopic composition of soil CO2 and the resultant fluxes, acting to reduce apparent fluxes due to CO2 consumption. Intra-site variability of CH4 and CO2 fluxes indicates that the use of two static chambers in a single site, while sufficient for the confirmation of gas uptake or emission, may be less adequate in the determination of actual rates of efflux/influx. Future studies should address this by either sampling a larger area, installing a greater number of chambers, or by utilizing entirely different methods, such as the use of eddy covariance techniques.
Download or read book Methane and Carbon Dioxide Cycling in Soils of the Harvard Forest written by Alexa Jaeger and published by . This book was released on 2018 with total page 18 pages. Available in PDF, EPUB and Kindle. Book excerpt: Soil is Earth's largest terrestrial carbon pool (Oertel et al., 2016) and can act as a net source of greenhouse gases (GHG). However, if organic material accumulates in soils faster than it is converted to CO2 by cellular respiration, soil becomes a smaller GHG source and even has the potential to become a GHG sink. Not much is known about factors that drive soil to be a source or a sink of GHG. Soil temperature and moisture have both been shown to correlate with CH4 emissions and temperature has been shown to correlate with CO 2 emissions (Jacinthe et al., 2015). Currently these relationships are not well constrained, particularly in upland soils, which are soils found at elevations between 100 and 500 m (Carating et al., 2014). Soil from the Harvard Forest was collected and used in two in-lab flux experiments to constrain the effect that soil moisture has on i.) the rate of CH4 and CO2 production/consumption and ii.) the fraction of injected CH4 that is oxidized to CO2 by soil microbes. The first experiment involved injecting vials containing soil samples with CH4 , taking an initial measurement with a residual gas analyzer (RGA), incubating for three days, and taking final measurements using the RGA. The results of this experiment indicated that cellular respiration is an important carbon source in these soils, with more CO2 coming from cellular respiration than from the oxidation of CH4. The second experiment involved injecting vials containing soil samples with CH4 and 14CH4 as a tracer, incubating for six days, and analyzing CO2 from each sample using a scintillation counter. This experiment showed a weak trend indicating that increased soil moisture may result in decreased CH4 oxidation. Results showed that decays per minute from the samples were lower than in a control. These results indicated that not all CO 2 from each sample was successfully captured and analyzed using the methods here. So while the trend may hold true, it should be supported by reconducting the experiment using a more reliable means of CO2 capture. The unexpected results from both experiments indicated that there is still much to be learned about the reactions that occur in these soils and how to perfect laboratory methods to study them.
Download or read book Carbon Nitrogen and Phosphorus Cycling in Forest Soils written by Robert G. Qualls and published by MDPI. This book was released on 2019-06-21 with total page 238 pages. Available in PDF, EPUB and Kindle. Book excerpt: The majority of carbon stored in the soils of the world is stored in forests. The refractory nature of some portions of forest soil organic matter also provides the slow, gradual release of organic nitrogen and phosphorus to sustain long term forest productivity. Contemporary and future disturbances, such as climatic warming, deforestation, short rotation sylviculture, the invasion of exotic species, and fire, all place strains on the integrity of this homeostatic system of C, N, and P cycling. On the other hand, the CO2 fertilization effect may partially offset losses of soil organic matter, but many have questioned the ability of N and P stocks to sustain the CO2 fertilization effect. Despite many advances in the understanding of C, N, and P cycling in forest soils, many questions remain. For example, no complete inventory of the myriad structural formulae of soil organic N and P has ever been made. The factors that cause the resistance of soil organic matter to mineralization are still hotly debated. Is it possible to “engineer” forest soil organic matter so that it sequesters even more C? The role of microbial species diversity in forest C, N, and P cycling is poorly understood. The difficulty in measuring the contribution of roots to soil organic C, N, and P makes its contribution uncertain. Finally, global differences in climate, soils, and species make the extrapolation of any one important study difficult to extrapolate to forest soils worldwide.
Download or read book Methane Cycling in Humid Tropical Forests written by Yit Arn Teh and published by . This book was released on 2005 with total page 350 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Carbon and Nitrogen Cycling in European Forest Ecosystems written by Ernst-Detlef Schulze and published by Springer Science & Business Media. This book was released on 2013-12-01 with total page 520 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume quantifies carbon storage in managed forest ecosystems not only in biomass, but also in all soil compartments. It investigates the interaction between the carbon and nitrogen cycles by working along a north-south transect through Europe that starts in northern Sweden, passes through a N-deposition maximum in central Europe and ends in Italy. For the first time biogeochemical processes are linked to biodiversity on a large geographic scale and with special focus on soil organisms. The accompanying CD-ROM provides a complete database of all flux, storage and species observations for modellers.
Download or read book Stable Isotope Analysis of Carbon Dioxide Exchange in a Tennessee Hardwood Forest written by David Randall Bowling and published by . This book was released on 1999 with total page 408 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Nitrogen Cycling in the Americas Natural and Anthropogenic Influences and Controls written by Luiz A. Martinelli and published by Springer Science & Business Media. This book was released on 2007-01-19 with total page 276 pages. Available in PDF, EPUB and Kindle. Book excerpt: Advances in our understanding of the nitrogen cycle and the impact of anthropogenic activities on regional to global scales depend on the expansion of scientific studies to these fast-developing regions. This book presents a series of studies from across the Americas whose aim is to highlight key natural processes that control nitrogen cycling as well as discuss the main anthropogenic influences on the nitrogen cycle in both the tropical and temperate regions of the Americas.
Download or read book An Investigation of Carbon Flows from Forest Soils in Relation to Climatic Warming written by Andrew Cross and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Rises in anthropogenic CO2 emissions are now widely acknowledged to be responsible for changes in the global climate, with potentially disastrous consequences if these rises continue unchecked. Although knowledge of ecosystem responses to climate change has improved, there are still large underlying uncertainties regarding their response to warming. Of all the ecosystems with the potential to mitigate rises in CO2, forests are arguably the most important because of their huge land area and store of carbon. A large proportion of the carbon stored in forests is found in the soil, and it is the response of this soil carbon to temperature that is the main determinant of a forest's ability to act as a carbon sink, or indeed source. Understanding the response of soil carbon flux to temperature, as well as the contribution of soil carbon flux to the carbon balance of forests as a whole is crucial in helping to improve modelling approaches. In this thesis I first examined the temperature response of old and new soil organic carbon from a Sitka spruce plantation under controlled laboratory conditions. Both the old and new soil organic carbon showed similar temperature sensitivities after prolonged incubation at 20 °C, thus implying a similar response to increasing temperatures. Using a variety of different methods (root intensity, meshing and stable isotope analysis) I then studied the responses under field conditions. These methods showed that autotrophic respiration was responsible for up to 50 % of total soil respiration, and was more sensitive to temperature than heterotrophic respiration. Finally, I compared the contributions and determinants (particularly temperature and moisture) of soil respiration fluxes to ecosystem fluxes at a temperate (Sitka spruce) and Mediterranean (Maritime pine) forest. Temperature was found to be the dominant driver of soil respiration fluxes at the temperature forest, whilst soil respiration was limited by moisture at the Mediterranean forest. Statistically significant relationships between net ecosystem productivity and soil respiration (and the stable isotope signature of soil respiration) were found at both forests, indicating a close coupling between above-ground processes and soil respiration.
Download or read book Warming and High Substrate Availability Increase Decomposition of Decades old Carbon in Temperate Forest Soils written by Francesca Mia Hopkins and published by . This book was released on 2013 with total page 192 pages. Available in PDF, EPUB and Kindle. Book excerpt: The effect of anthropogenic CO2 emissions on climate in the 21st century depends in part on the response of terrestrial carbon cycle. Rising atmospheric CO2 levels are buffered by increased uptake of carbon into terrestrial ecosystems, but concomitant global warming will increase the rate of release of this carbon back to the atmosphere through respiration. Future climate depends on the relative stimulation of these processes, and the effects that warming and elevated CO2 concentrations have on the length of time carbon is stored in the biosphere. A major uncertainty in future climate projections is how these changes will affect the stability of soil carbon stocks. This is particularly critical for the large pool of relatively slow cycling carbon that could become a net source of CO2 to the atmosphere for decades if its decomposition rate increases with global warming. We studied soils from two decade-long Free Air CO2 Enrichment (FACE) experiments in temperate forests in North Carolina and Wisconsin to examine the effects of these global changes on the stability of soil carbon. We took advantage of the decade-long carbon isotope label in soils coming from additions of fossil-derived CO2 over the length of the experiment. The label allowed us to distinguish the effects of warming and substrate availability on decades-old carbon that pre-dated the FACE experiments. We found that carbon that was decades old, as well as carbon that was younger, were equally vulnerable to the effect of warming. We estimate that the majority (50-95%) of carbon in the topsoils of these temperate forests could contribute a feedback to global warming. Another key uncertainty is whether additional carbon added to soils from higher future productivity is stored or respired quickly back to the atmosphere. We simulated the effect of higher substrate availability in soils, and found that it promoted increased decomposition of soil carbon, but did not affect the age of respired CO2. Warming enhanced this effect, increasing respiration rates even more for a given increase in substrate. Our findings suggest that increased substrate from productivity enhancement is not likely to be stored in soils.
Download or read book The Impact of an Active Soil Microbial Community on Greenhouse Gas Emissions in Arctic Cryosols written by Ianina Altshuler and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: "Anthropogenic climate change is thought to have a disproportionately larger impact on polar regions, resulting in permafrost thaw and microorganism mediated greenhouse gas (GHG) emission. Permafrost soils contain between 25-50 % of the total soil organic carbon pool and as permafrost thaws, this carbon will become accessible to microbial degradation. Carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) are the most important GHGs and their flux from permafrost affected soils contributes to a positive feedback loop of climatic warming. However, our understanding of how microorganisms contribute to the biogeochemical cycling and flux of these gases in Arctic soils remains limited. Topography of the Arctic landscape has a significant impact on GHG emissions as evidenced by the flux at the ice-wedge polygon (IWP) terrain. The wetter tough soils exhibited higher emissions of CO2 and N2O, but lower uptake of CH4, compared to the drier polygon interior soils. The elevated CO2 and N2O fluxes, and the lower CH4 uptake from troughs is concerning from a climate warming perspective since parts of the Arctic are predicted to become warmer and wetter. Topography also affected the composition of the overall microbial community, with the trough soils having a higher proportion of Betaproteobacteria, Deltaproteobacteria, and Bacterioidetes but a lower proportion of Acidobacteria compared to polygon interior soils. The community of nitrogen fixers, methanotrophs, and denitrifiers was also affected by the topography with all three groups showing unique structures. Overall, members of the nitrogen-fixing and denitrifying bacteria included Rhizobiaceae, Nostocaceae, Cyanothecaceae, Rhodobacteraceae, Burkholderiaceae, Chloroflexaceae, Azotobacteraceae, and Ectothiorhodospiraceae. Moreover, these organisms appear to be active in the soils, as metatranscriptomic RNA analysis was also able to detect these microbial clades. The active methanotrophs in these soils are likely part of the USC[alpha] cluster of currently uncultured high-affinity methanotrophs, as evidenced by stable isotope probing (SIP) of soils exhibiting CH4 uptake. SIP analysis coupled with metagenome binning lead to the identification of several intermediate-high quality MAGs (metagenome assemble genomes). One Alphaproteobacterial MAG was identified that contained many of the methane cycling genes including a soluble methane monooxygenase (mmoX) and genes involved in the serine cycle for assimilating formaldehyde characteristic of type II methanotrophs. This MAG also contained genes for ammonia assimilation, biopolymer production, and mercury detoxification. In addition to identifying non-culturable members of the community through metagenome binning, sequencing of culturable isolates reveal presence of carbon cycling genes involved in fermentation, CO2 fixation, denitrification, polysaccharide and aromatic compound metabolism. Suggesting that the microbial community at the IWP terrain is poised to degrade the thawing carbon stores in permafrost. In addition to topography affecting the microbial community structure, key microbial members across the IWP terrain also appear to have positive and negative impacts on other microbial species. This was determined by developing a novel hybrid network analysis to determine species interactions within of the microbial community. Overall, members of Proteobacteria, Candidatus Rokubacteria, and Actinobacteria phyla tended to have a positive impact, while members of Verrucomicrobia and Acidobacteria had a negative impact on other microbials members. These results indicate that both environmental abiotic parameters and biotic interactions impact the microbial community structure and possibly GHG fluxes from soils. " --
Download or read book Soil Processes and the Carbon Cycle written by Rattan Lal and published by CRC Press. This book was released on 2018-02-06 with total page 624 pages. Available in PDF, EPUB and Kindle. Book excerpt: World soils contain about 1500 gigatons of organic carbon. This large carbon reserve can increase atmospheric concentrations of CO2 by soil misuse or mismanagement, or it can reverse the 'greenhouse' effect by judicious land use and proper soil management. Soil Processes and the Carbon Cycle describes soil processes and their effects on the global carbon cycle while relating soil properties to soil quality and potential and actual carbon reserves in the soil. In addition, this book deals with modeling the carbon cycle in soil, and with methods of soil carbon determinations.
Download or read book Stable Isotope Ecology written by Brian Fry and published by Springer Science & Business Media. This book was released on 2007-01-15 with total page 318 pages. Available in PDF, EPUB and Kindle. Book excerpt: A solid introduction to stable isotopes that can also be used as an instructive review for more experienced researchers and professionals. The book approaches the use of isotopes from the perspective of ecological and biological research, but its concepts can be applied within other disciplines. A novel, step-by-step spreadsheet modeling approach is also presented for circulating tracers in any ecological system, including any favorite system an ecologist might dream up while sitting at a computer. The author’s humorous and lighthearted style painlessly imparts the principles of isotope ecology. The online material contains color illustrations, spreadsheet models, technical appendices, and problems and answers.
Download or read book Soil Respiration and the Environment written by Luo Yiqi and published by Elsevier. This book was released on 2010-07-20 with total page 334 pages. Available in PDF, EPUB and Kindle. Book excerpt: The global environment is constantly changing and our planet is getting warmer at an unprecedented rate. The study of the carbon cycle, and soil respiration, is a very active area of research internationally because of its relationship to climate change. It is crucial for our understanding of ecosystem functions from plot levels to global scales. Although a great deal of literature on soil respiration has been accumulated in the past several years, the material has not yet been synthesized into one place until now. This book synthesizes the already published research findings and presents the fundamentals of this subject. Including information on global carbon cycling, climate changes, ecosystem productivity, crop production, and soil fertility, this book will be of interest to scientists, researchers, and students across many disciplines. A key reference for the scientific community on global climate change, ecosystem studies, and soil ecology Describes the myriad ways that soils respire and how this activity influences the environment Covers a breadth of topics ranging from methodology to comparative analyses of different ecosystem types The first existing "treatise" on the subject
Download or read book Activity Diversity and Community Structure of Aerobic Methane Oxidizing and Carbon Dioxide Producing Bacteria in Soils from the Canadian High Arctic written by Christine Martineau and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Trace Gas Exchange in Forest Ecosystems written by R. Gasche and published by Springer Science & Business Media. This book was released on 2002 with total page 362 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume summarizes the current knowledge on the exchange of trace gases between forests and the atmosphere with the restriction that exclusively carbon and nitrogen compounds are included. For this purpose the volume brings together and interconnects knowledge from different disciplines of biological and atmospheric sciences. It covers microbial and plant processes involved in the production and consumption of these trace gases; the exchange processes between forest soils and vegetation on the one hand, and the atmosphere on the other hand; the fate of the trace gases exchanged inside the atmosphere as well as environmental influences on the exchange of trace gases between forest ecosystems and the atmosphere. With this interdisciplinary approach the volume provides the background for an evaluation of the exchange of trace gases between forest ecosystems and the atmosphere and man-made disturbances of this exchange.
Download or read book Forest and Rangeland Soils of the United States Under Changing Conditions written by Richard V. Pouyat and published by Springer Nature. This book was released on 2020-09-02 with total page 306 pages. Available in PDF, EPUB and Kindle. Book excerpt: This open access book synthesizes leading-edge science and management information about forest and rangeland soils of the United States. It offers ways to better understand changing conditions and their impacts on soils, and explores directions that positively affect the future of forest and rangeland soil health. This book outlines soil processes and identifies the research needed to manage forest and rangeland soils in the United States. Chapters give an overview of the state of forest and rangeland soils research in the Nation, including multi-decadal programs (chapter 1), then summarizes various human-caused and natural impacts and their effects on soil carbon, hydrology, biogeochemistry, and biological diversity (chapters 2–5). Other chapters look at the effects of changing conditions on forest soils in wetland and urban settings (chapters 6–7). Impacts include: climate change, severe wildfires, invasive species, pests and diseases, pollution, and land use change. Chapter 8 considers approaches to maintaining or regaining forest and rangeland soil health in the face of these varied impacts. Mapping, monitoring, and data sharing are discussed in chapter 9 as ways to leverage scientific and human resources to address soil health at scales from the landscape to the individual parcel (monitoring networks, data sharing Web sites, and educational soils-centered programs are tabulated in appendix B). Chapter 10 highlights opportunities for deepening our understanding of soils and for sustaining long-term ecosystem health and appendix C summarizes research needs. Nine regional summaries (appendix A) offer a more detailed look at forest and rangeland soils in the United States and its Affiliates.
