Download or read book The Effects of Changing Precipitation Patterns on Soil Microbial Communities and Nitrogen Cycling in the New Jersey Pinelands written by William Joel Landesman and published by . This book was released on 2009 with total page 186 pages. Available in PDF, EPUB and Kindle. Book excerpt: I studied the potential effects of a change in the amount, frequency and timing of precipitation on soil microbes and nitrogen cycling in the New Jersey Pinelands. I performed a two year field manipulation of precipitation amount and measured the response of the microbial community, potential net nitrogen mineralization and amino acid production. I found that soil microbes were not affected by rain exclusion or a doubling of rainfall. Nematode densities, but not community composition, were sensitive to precipitation amount. A large accumulation of ammonium in drought plots suggested sustained microbial activity under extreme drought conditions. I observed small changes in potential net nitrogen mineralization due to the effects of soil moisture on diffusion and immobilization. I measured the short-term response of the microbial community to a rewetting of dry soil and found a very rapid (three hour) change in the microbial community. The accumulation of ammonium within drought plots appears to have suppressed fungal biomass following the rewetting event. In a two year winter study, I found no long-term effect of supplemental winter rainfall on the soil microbial community. Elevated winter precipitation prevented ammonium accumulation, presumably by protecting plant roots from freeze damage. I found that supplemental watering insulates soil microbes from cold stress over the short-term (days), but that mid-winter declines in biomass due to cold soil. These experiments demonstrate that soil microbial communities in Pinelands soils are highly tolerant of abiotic stressors such as drought, upshock stress and soil freezing. Recovery from these disturbances is extremely rapid, occurring on the scale of hours to days. I conclude that changing precipitation patterns will not have a direct, long-term effect on soil microbial communities. Changes in precipitation patterns are more likely to alter nitrogen cycling rates via the influence on nitrogen diffusion and plant and microbial uptake. Furthermore, precipitation-induced changes in nematode densities may have important implications for nitrogen cycling in the New Jersey Pinelands.

Download or read book Gases Advances in Research and Application 2011 Edition written by and published by ScholarlyEditions. This book was released on 2012-01-09 with total page 2282 pages. Available in PDF, EPUB and Kindle. Book excerpt: Gases: Advances in Research and Application: 2011 Edition is a ScholarlyEditions™ eBook that delivers timely, authoritative, and comprehensive information about Gases. The editors have built Gases: Advances in Research and Application: 2011 Edition on the vast information databases of ScholarlyNews.™ You can expect the information about Gases in this eBook to be deeper than what you can access anywhere else, as well as consistently reliable, authoritative, informed, and relevant. The content of Gases: Advances in Research and Application: 2011 Edition has been produced by the world’s leading scientists, engineers, analysts, research institutions, and companies. All of the content is from peer-reviewed sources, and all of it is written, assembled, and edited by the editors at ScholarlyEditions™ and available exclusively from us. You now have a source you can cite with authority, confidence, and credibility. More information is available at http://www.ScholarlyEditions.com/.

Download or read book Impacts of Changing Precipitation on Nitrogen Cycling in Different Landscape Positions and Cropping Systems written by Kathryn Glanville and published by . This book was released on 2020 with total page 89 pages. Available in PDF, EPUB and Kindle. Book excerpt: Soil nitrogen (N) influences crop yields and can interact with climate change. Soil N has many transformations and transfers that are hard to quantify and control. These N transformations and transfers are mediated by many factors, including temperature, water, and carbon. Thus, impending climate change may strongly affect N cycling across cropping systems. To minimize N losses and increase crop production, we must maximize N use efficiency (NUE). Past research shows precipitation and soil moisture act as the primary physical drivers of terrestrial N cycling and losses. To improve NUE with changing precipitation patterns, controls on N cycling in terrestrial systems must be identified. Thus, experiments to elucidate the linkage between hydrological and biogeochemical controls are valuable (Chapter 1). Many aspects of the N cycle are influenced by a changing climate - two are especially important: nitrous oxide fluxes (N2O) and biological nitrogen fixation (BNF). N2O is a powerful greenhouse gas with over 250 times the radiative forcing of CO2. In Chapter 2, I test the hypothesis that changing rainfall patterns strongly alter N2O fluxes in agricultural soils as modulated by cropping system. I use rainfall manipulation shelters to expose soils to the same amount of rainfall delivered at different intervals (3-days, 14-days, and 28-days). Results from the 2016 and 2017 field seasons show cumulative N2O fluxes were 1.4 to 2 times higher when rainfall occurred in 28-day rather than shorter intervals in corn systems. Fluxes were related to changes in denitrifier enzyme activity for both years. In switchgrass systems N2O emissions were not significantly affected by rainfall intervals.In Chapter 3, I test the hypothesis that changing rainfall patterns that alter N2O fluxes will be modulated by landscape position as landscape position affects soil texture and carbon. Over two field seasons cumulative N2O fluxes were higher in toeslope positions than in summit positions, and longer rainfall intervals had higher fluxes in summits only, consistent with higher soil carbon and finer soil texture in toeslope positions. Knowledge of these landscape patterns deserve inclusion in models of current and future climate change effects in order to better quantify and mitigate agricultural N2O fluxes.In Chapter 4, I test the hypothesis that BNF is particularly vulnerable to changing rainfall patterns in till vs. no-till and in summit vs. toeslope positions due to differences in texture and organic matter. Results reinforce the importance of topographic position for predicting soybean BNF and show that summit positions are more sensitive to additional rainfall. Results also show changes in rainfall intensity affect BNF in tilled differently than in no-till soils. Models that incorporate these interactions will be better able to characterize legume crop performance and N fixation across landscapes and improve global estimates for BNF. Understanding these interactions in the agricultural US Midwest may help us improve sustainability of N use in cropping systems with a changing climate.

Download or read book Greenhouse Gas Emissions and Mitigation Microbes Mechanisms and Modeling written by Baoli Zhu and published by Frontiers Media SA. This book was released on 2024-05-29 with total page 115 pages. Available in PDF, EPUB and Kindle. Book excerpt: Currently, the global average temperature is projected to increase by 0.2 °C per decade due to past and ongoing greenhouse gas (GHG) emissions. To limit global warming to 1.5 °C above pre-industrial levels, not only does carbon dioxide (CO2) emission need to reach net zero around 2050, but the emissions of other GHGs also have to reduce substantially. Nitrous oxide (N2O) and methane (CH4) are very important GHGs, and their global warming potentials are 300 and 25 times that of CO2 over a 100-year time scale. Since pre-industrial times, atmospheric N2O concentrations have increased by more than 20%, and CH4 concentrations have nearly tripled to the current 1900 ppb. Studies have suggested that the ongoing increase of atmospheric N2O and CH4 emissions is mostly attributed to microbial activities.

Download or read book Response of Soil Microbial Communities and Nitrogen Cycling Processes to Changes in Vegetation Inputs written by Elizabeth Ann Brewer and published by . This book was released on 2010 with total page 114 pages. Available in PDF, EPUB and Kindle. Book excerpt: Changes in the type and amount of plant inputs can occur gradually, as with succession, or rapidly, as with harvesting or wildfire. With global change it is anticipated that both gradual and immediate scenarios will occur at increasing frequency. Changes in vegetation inputs alter the quality and quantity of soil organic matter inputs, thus influencing the composition of soil microbial communities and the nutrient cycles they mediate. Understanding the relationship of soil organic matter inputs on soil microbial communities and nutrient cycles will be beneficial in predicting responses to changes in vegetation inputs. During the last 100-150 years, the vegetation of the Rio Grande Plains of the United States has been shifting from grasslands/savannas to woodlands as the result of encroachment of N2-fixing trees and their associated plant communities. The structure and diversity of soil microbial communities were examined under woody species and remnant grasslands. In addition, relationships between soil microbial communities and soil physical and chemical characteristics were explored. Soil microbial communities differed in soils under N2-fixing trees and associated vegetation compared to remnant grasslands. Differences in both fungal and bacterial communities were anticipated with vegetation shifts; however, only fungal communities correlated with vegetation, whereas bacterial communities were influenced by spatial heterogeneity. Soil microbial N cycling was investigated in long-term (>10 years) organic matter manipulations in an old-growth forest, dominated by large Pseudotsuga menziesii (Mirb.) Franco (Douglas-fir). The objectives of this research were to: 1) determine if long-term organic matter manipulations in old-growth forests altered microbial N cycling, 2) determine the contribution of litter to N cycling, and 3) determine if litter quality (low C/N red alder and high C/N Douglas-fir) affected the contribution of litter-derived N to N transformations. Long-term organic matter manipulations were found to affect microbial C and N cycling, but to a lesser degree than anticipated. After 10 years of organic matter exclusions and additions, microbial communities in all treatments remained N limited, although N limitation was less severe in organic matter exclusion treatments. Adding leached litter to control and organic matter exclusion soils initially altered N processes but differences dissipated during a 151-day incubation. Litter quality had little impact on the N cycling and litter made modest contributions to N mineralization and nitrification. The exclusion of organic matter altered the functionality of the microbial community to access litter-derived N. Both the gradual establishment of woody clusters on grassland and abrupt manipulations of old-growth vegetation inputs elicited responses in microbial communities and N cycling. Although some responses were subtle, they nonetheless support the responsiveness and importance of microbial communities to soil processes. Understanding feedbacks among plant inputs, microbial communities and nutrient cycles will aid in predicting microbial, ecosystem, and global responses to vegetation changes.

Download or read book The Influence of Altered Precipitation Frequency on Biological Soil Crust Bacterial Community Structure Diversity and Ecosystem Functions written by Natalie Kristine Myers and published by . This book was released on 2013 with total page 52 pages. Available in PDF, EPUB and Kindle. Book excerpt: Biological soil crusts (BSCs), topsoil microbial assemblages typical of arid land ecosystems, provide essential ecosystem services such as soil fertilization and stabilization against erosion. Cyanobacteria and lichens, sometimes mosses, drive BSC as primary producers, but metabolic activity is restricted to periods of hydration associated with precipitation. Climate models for the SW United States predict changes in precipitation frequency as a major outcome of global warming, even if models differ on the sign and magnitude of the change. BSC organisms are clearly well adapted to withstand desiccation and prolonged drought, but it is unknown if and how an alteration of the precipitation frequency may impact community composition, diversity, and ecosystem functions. To test this, we set up a BSC microcosm experiment with variable precipitation frequency treatments using a local, cyanobacteria-dominated, early-succession BSC maintained under controlled conditions in a greenhouse. Precipitation pulse size was kept constant but 11 different drought intervals were imposed, ranging between 416 to 3 days, during a period of 416 days. At the end of the experiments, bacterial community composition was analyzed by pyrosequencing of the 16s rRNA genes in the community, and a battery of functional assays were used to evaluate carbon and nitrogen cycling potentials. While changes in community composition were neither marked nor consistent at the Phylum level, there was a significant trend of decreased diversity with increasing precipitation frequency, and we detected particular bacterial phylotypes that responded to the frequency of precipitation in a consistent manner (either positively or negatively). A significant trend of increased respiration with increasingly long drought period was detected, but BSC could recover quickly from this effect. Gross photosynthesis, nitrification and denitrification remained essentially impervious to treatment. These results are consistent with the notion that BSC community structure adjustments sufficed to provide significant functional resilience, and allow us to predict that future alterations in precipitation frequency are unlikely to result in severe impacts to BSC biology or ecological relevance.

Download or read book Impact of Changing Precipitation Patterns on the Plant microbial Response to Rewetting written by Ilonka Engelhardt and published by . This book was released on 2018 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Water availability governs terrestrial nutrient cycles by impacting the functioning of both plants and of soil microorganisms. The predicted changes in precipitation patterns (i.e. the magnitude and frequency of precipitation events) associated with climate change, will thus likely have important consequences on ecosystem functioning. Dry and seasonally dry ecosystems are particularly vulnerable to changes in precipitation patterns, as they are already constrained to a large extent by water availability. However, more mesic systems may also experience dry periods that may impact plant-soil functions. In this thesis, experiments in soil-only systems and plant-soil systems were used to gain insight into how the legacy effects of several weeks of exposure to contrasted precipitation patterns set the scene for the rewetting response of the system. First, in an experiment using soil-only mesocosms, we evaluated the effects of contrasting precipitation regimes on the actively growing as well as the inactive bacterial and fungal communities 2 and 5 days after rewetting, using an 18O-SIP (stable isotope probing) approach by applying H218O followed by metagenomics targeting soil bacteria and fungi. Second, we performed two separate and complementary experiments using plant-soil mesocosms with wheat plant cover. The first plant-soil experiment focused on soil depth. It determined the effects of contrasting precipitation patterns on the flux of C from plants to microbes and the microbial response to rewetting at different soil depths, using a heavy isotope tracer approach (13C-CO2) and 18O-SIP with metagenomics respectively. The second plant-soil experiment evaluated the effects of a history of contrasting precipitation patterns on the dynamics of the rewetting response of the plant-soil system over time (over 29 hours post-rewetting). In addition, two levels of N inputs allowed to determine how N availability modulated plant-soil responses. The response of the potentially active soil bacterial and fungal communities to rewetting was assessed using targeted metagenomics. The responses of biogeochemical cycles were evaluated using heavy isotope tracers (13C-CO2 and 15N-NO3-) to quantify C flux from plants to soil microorganisms and plant-microbial competition for N over time post-rewetting.We found that precipitation patterns shaped plant morphology and physiology, microbial community composition as well as soil N cycling in our systems, which set contrasting scenes for the rewetting responses in our systems. In particular, infrequent precipitation patterns (cycles of longer dry periods followed by larger magnitude rain events) resulted in increased microbial N transformation potentials and smaller inorganic N pools. The rewetting responses were determined by evaluating C dynamics (plant-microbial coupling and soil CO2 efflux rate), N dynamics (plant-microbial competition for N and soil N2O efflux rate) and microbial dynamics (composition of active and potentially active bacterial and fungal communities after rewetting). First, we found that plant-microbial coupling (i.e the microbial assimilation of C from fresh photosynthate) may be reduced under more infrequent precipitation patterns, especially near the soil surface, and under conditions of low N availability. Our findings also suggest that whilst in soil-only systems, dead microbial cells appear to be a major source fuelling soil CO2 efflux pulse upon rewetting, in plant-soil systems root respiration plays an important role in the magnitude of the CO2 efflux upon rewetting. Second, concerning soil N dynamics, we found, in concurrence with previous studies, that soil microorganisms were the stronger competitor for N over short time scales, likely due to their overall fast response rates and high affinity for substrate, whilst plants outcompeted soil microbes for soil N assimilation, over longer time scales likely taking advantage of the fast microbial turnover (...).

Download or read book New Jersey Pinelands National Reserve Management Plan written by and published by . This book was released on 1980 with total page 326 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Official Meeting Program written by Ecological Society of America. Meeting and published by . This book was released on 2008 with total page 392 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Link Between Nitrogen Cycling and Soil Microbial Community Composition in Forest Soils of Western Oregon written by Stephanie A. Boyle and published by . This book was released on 2007 with total page 142 pages. Available in PDF, EPUB and Kindle. Book excerpt: The objectives of this thesis were to examine the links between soil microbial community composition and function using the nitrogen (N) cycle as a model for these interactions and to assess the impact of environmental factors such as microclimate, vegetation type, and nutrient availability on microbial diversity and N transformations in forest soils. The first study consisted of a reciprocal transfer experiment where soil cores were transferred between high-elevation forest and adjacent meadow environments. It focused on bacterial denitrifying communities by measuring denitrification enzyme activity and community composition as determined by terminal restriction fragment length polymorphism (T-RFLP) profiles targeting the gene for nitrous oxide reductase (nosZ). Results from this experiment showed that while transferring meadow soils into forests increased denitrification rate, denitrifying community composition did not appear to change after two years. The second study examined N cycling and microbial community composition in soils from 20-year-old experimental tree plantations with pure stands of Douglas fir (Pseudotsuga menziesii) and red alder (Alnus rubra) in a high- and a low-productivity forest. 15N isotope dilution was combined with antibiotics to assess the roles of bacteria and fungi in N mineralization and nitrification. Data showed that nitrification was a major sink for NH4+ in all soil types and bacteria were the primary nitrifiers. Increased ammonification following antibiotic additions suggested that organic N may be important for the growth of heterotrophic bacteria and fungi. Results of nitrification potential assays showed that most nitrification was acetylene insensitive (autotrophic). Community composition of ammonia-oxidizing bacteria and archaea were assessed by targeting bacterial and archaeal ammonia-monooxygenase (amoA) genes. The composition and population size of ammonia-oxidizing bacteria differed between Douglas fir and red alder and tended to group with Nitrosospira clusters 2 and 4. Archaeal amoA was only amplified from the high-productivity site and grouped with other archaeal clones from soil and estuary sediments. Environmental factors affected rates of N cycling within two years, but community compositional changes responded more slowly, e.g., nitrifying communities differed between 20-year-old tree stands. This suggests that if environmental changes persist they may lead to changes in microbial community composition.

Download or read book The Effects of Anthropogenic Stress on Nitrogen cycling Microbial Communities in Temperate and Tropical Soils written by George S. Hamaoui (Jr.) and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: In this dissertation several research studies are discussed that characterize the effects of anthropogenic, or human-induced, stress on both ammonia-oxidizing and total bacterial soil microbial communities. The disturbances of land-use change in tropical, South American rainforests and artificial warming and nitrogen (N) fertilization in temperate, North American forests were investigated as these disturbances represent past and current disturbances caused by human landscape alteration and climate change. Initially, the response of soil ammonia-oxidizing microbial communities to land-use change from primary rainforest to pasture and, finally, back to secondary forest was determined. Next, these analyses of land-use change effects were expanded to the total bacterial community in these rainforest soils sampled annually for three years. Lastly, the effects of increasing soil temperature and N-deposition on ammonia-oxidizing microbial communities in temperate forests were characterized. Land-use change affected ammonia-oxidizing communities in tropical soils. Both the abundance of ammonia-oxidizer marker genes and their community structure shifted due to land-use changes. Interestingly, phylogenetic analyses showed that community structural changes in ammonia-oxidizing thaumarchaea are driven by a shift away from primary rainforest, old pasture, and secondary forest clusters to separate clusters for young pasture. Additionally, there was a nearly complete disappearance in young pasture, old pasture, and secondary forest sites of a thaumarchaeal ammonia-oxidizing genus, the Nitrosotalea. We found that many of the bacterial community responses to land-use change stayed consistent between land-use types across all three years, especially in regards to OTU richness and Faith's phylogenetic diversity. Bacterial community turnover, or distance-decay, was significantly greater (P 0.05) in forests compared to pastures for two out of three years sampled. Lastly, two bacterial species, Rhodomicrobium udaipurense and Anaeromyxobacter dehalogens, were found to be exclusive indicator species for the pasture land-use type across all sampling time points. Finally, when investigating the effects of increasing soil temperatures and N-deposition rates on temperate forest soil N-cycling, potential N-mineralization and nitrification rates and chitinase enzyme activity showed no difference between treatments (P 0.05). Bacterial, fungal, and archaeal rRNA genes and thaumarchaeal amoA genes showed no significant difference between treatments. There were significant differences in ammonia-oxidizer community structure between control and heated plus nitrogen treatments. The majority of archaeal ammonia-oxidizer species were most closely related to Nitrosotalea and Nitrososphaera spp. However, the organic horizon in the heated plus nitrogen treatment was dominated by sequences most closely related to Nitrosopumilus maritimus. Taken together, these results can provide a conceptual foundation as to how anthropogenic stressors can alter microbial communities in tropical and temperate forests soils. These communities are critical to global biogeochemical cycling and climate regulation. By charactering how these communities respond to various anthropogenic stressors, the scientific community can begin to use this information to develop more holistic biogeochemical models to predict shifts in nutrient flow and greenhouse gas production.

Download or read book Effect of Increasing Nitrogen Deposition on Soil Microbial Communities written by and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Increasing nitrogen deposition, increasing atmospheric CO2, and decreasing biodiversity are three main environmental changes occurring on a global scale. The BioCON (Biodiversity, CO2, and Nitrogen) ecological experiment site at the University of Minnesota's Cedar Creek Ecosystem Science Reserve started in 1997, to better understand how these changes would affect soil systems. To understand how increasing nitrogen deposition affects the microbial community diversity, heterogeneity, and functional structure impact soil microbial communities, 12 samples were collected from the BioCON plots in which nitrogenous fertilizer was added to simulate the effect of increasing nitrogen deposition and 12 samples from without added fertilizer. DNA from the 24 samples was extracted using a freeze-grind protocol, amplified, labeled with a fluorescent dye, and then hybridized to GeoChip, a functional gene array containing probes for genes involved in N, S and C cycling, metal resistance and organic contaminant degradation. Detrended correspondence analysis (DCA) of all genes detected was performed to analyze microbial community patterns. The first two axes accounted for 23.5percent of the total variation. The samples fell into two major groups: fertilized and non-fertilized, suggesting that nitrogenous fertilizer had a significant impact on soil microbial community structure and diversity. The functional gene numbers detected in fertilized samples was less that detected in non-fertilizer samples. Functional genes involving in the N cycling were mainly discussed.

Download or read book Effects of Increased Nitrogen Deposition on Forest Soil Nitrogen Cycling and Microbial Community Structure written by Matthew David Wallenstein and published by . This book was released on 2004 with total page 222 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Soil Microbial Community Structure and Function Along Environmental Gradients Implications for Wetland Nitrogen Cycling written by and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Nitrogen Uptake in Lowland Plant Communities of the New Jersey Pine Barrens written by Joan G. Ehrenfeld and published by . This book was released on 1981 with total page 148 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Soil Nitrogen Cycling and Ectomycorrhizal Community Composition Following Disturbance in Michigan Jack Pine Forests written by Stephen Daniel LeDuc and published by . This book was released on 2009 with total page 334 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Ecological Society of America Annual Meeting Abstracts written by Ecological Society of America. Meeting and published by . This book was released on 2004 with total page 612 pages. Available in PDF, EPUB and Kindle. Book excerpt: