Download or read book Response of Soil Microbial Communities to Physical and Chemical Disturbances written by Guilherme M. Chaer and published by . This book was released on 2008 with total page 272 pages. Available in PDF, EPUB and Kindle. Book excerpt: General introduction; Land use impact on the stability of soil microbial community composition and enzyme activities to heat shock; Shifts in microbial community composition and physiological profiles across a gradient of induced soil degradation (GRIND); Development and validation of a soil quality index based on the equilibrium between soil organic matter and biochemical properties in an undisturbed forest ecosystem. The objectives of this thesis were to evaluate the responses of soil microbial communities to physical and chemical disturbances, and associate these responses with soil functional stability and changes in soil quality. The first study consisted of application of heat shocks (HS) to soils with contrasting land use history to evaluate differences in the stability of soil enzymes (laccase, cellulase and fluorescein diacetate hydrolysis) and microbial community composition as determined by phospholipid fatty acid (PLFA) analysis. The conversion of land use from forest to agriculture resulted in a new microbial community that was less functionally stable. Loss of stability was indicated by the reduced of laccase and cellulase activities in the agricultural soil, which suggested a less diverse community of microorganisms capable of producing these enzymes. The second study examined changes in microbial community composition and diversity that occurred across a gradient of soil disturbance. Disturbances were simulated by tillage events applied at different intensities to a 12-year-old fallow area. These treatments caused degradation of several soil physico-chemical properties, and alterations in microbial structure based on PLFA and terminal restriction fragment length polymorphism (T-RFLP) analyses, and in metabolic potential based on community level physiological profiles (CLPPs). Multivariate ordination of soil properties revealed the formation of a linear gradient of soil degradation that was significantly correlated with CLPPs, but not with T-RFLP and PLFA profiles. Nevertheless, changes observed in microbial community structure were significantly associated with decreases in soil organic C and field hydraulic conductivity. The third study demonstrated that undisturbed forest soils from western Oregon express an equilibrium between soil organic matter and biochemical properties. A model fitted through multiple regression analysis showed that phosphatase activity and microbial biomass were able to explain 97% of the soil organic C in these soils. This equilibrium was disrupted when a soil from an old-growth site was submitted to chemical stresses (Cu addition or pH alteration) and physical disturbances (wet-dry or freeze-thaw cycles). The magnitude of this disruption was consistently expressed by the ratio between soil C predicted by the model (Cp), and soil C that was measured (Cm). This ratio is proposed as biochemically-based index of soil quality.
Download or read book Microbial Community Composition in Response to Soil Factors and Disturbance on Serpentine Soils written by Shira Hava Degrood and published by . This book was released on 2005 with total page 144 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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 In the Light of Evolution written by National Academy of Sciences and published by National Academies Press. This book was released on 2017-01-01 with total page 433 pages. Available in PDF, EPUB and Kindle. Book excerpt: Biodiversity-the genetic variety of life-is an exuberant product of the evolutionary past, a vast human-supportive resource (aesthetic, intellectual, and material) of the present, and a rich legacy to cherish and preserve for the future. Two urgent challenges, and opportunities, for 21st-century science are to gain deeper insights into the evolutionary processes that foster biotic diversity, and to translate that understanding into workable solutions for the regional and global crises that biodiversity currently faces. A grasp of evolutionary principles and processes is important in other societal arenas as well, such as education, medicine, sociology, and other applied fields including agriculture, pharmacology, and biotechnology. The ramifications of evolutionary thought also extend into learned realms traditionally reserved for philosophy and religion. The central goal of the In the Light of Evolution (ILE) series is to promote the evolutionary sciences through state-of-the-art colloquia-in the series of Arthur M. Sackler colloquia sponsored by the National Academy of Sciences-and their published proceedings. Each installment explores evolutionary perspectives on a particular biological topic that is scientifically intriguing but also has special relevance to contemporary societal issues or challenges. This tenth and final edition of the In the Light of Evolution series focuses on recent developments in phylogeographic research and their relevance to past accomplishments and future research directions.
Download or read book Microbial Communities in Soil written by V. Jensen and published by Springer. This book was released on 1986-04-30 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Effects of Nutrient Availability and Disturbance on the Composition and Diversity of Soil Microorganisms written by Joshua C. Thigpen and published by . This book was released on 2015 with total page 87 pages. Available in PDF, EPUB and Kindle. Book excerpt: Determining how factors such as disturbance and nutrient availability affect species diversity in a community has been a major goal of community ecology. The purpose of this study was to look at how species diversity and composition of soil bacterial communities are affected by nutrient addition and disturbance. I characterized soil microbial communities at the long-term ecological research site at the West Research Campus (WRC) located in Pitt County, NC. Briefly, DNA extracted from soils was analyzed using amplicon sequencing of the 16S ribosomal RNA gene. The Illumina Platform was used to sequence the bacterial DNA from each sample, and the Mothur Pipeline was used to analyze the DNA sequences. I hypothesized that changes in nutrient availability and disturbance would impact soil microbial community composition and diversity through direct and indirect effects mediated by plant-soil interactions. My research complemented previous work carried out in the WRC determining the effects of nutrient addition and disturbance on plant communities. Analysis of 2013 plant data showed that mowing increased plant species richness, and fertilization decreased plant species richness significantly. The experimental treatments as well as the proximity of the blocks to a drainage ditch all had significant effects on plant community composition. Analysis of the microbial community data showed that both fertilization and mowing significantly increased mean species richness. Relative abundance microbial community composition varied significantly due to the proximity of the blocks to the ditch. Presence/absence microbial community analyses showed significant effects of the treatments, as well as ditch proximity on microbial composition differences. Also, unknown microbial communities showed significant variation of the communities due to the treatments. The results of the presence/absence analysis and the unknown microbial community analysis show the importance of rare taxa and unknown microbial communities to the differences in composition of our soil microbial communities. Analysis of the soil chemical and physical data showed very little variation due to the treatments. This study will contribute to our understanding of how both plant and soil bacterial community diversity are affected by anthropogenic nutrient addition and disturbances. Maintaining diversity is important for ecosystem stability and functioning.
Download or read book In the Light of Evolution written by National Academy of Sciences and published by . This book was released on 2007 with total page 388 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Arthur M. Sackler Colloquia of the National Academy of Sciences address scientific topics of broad and current interest, cutting across the boundaries of traditional disciplines. Each year, four or five such colloquia are scheduled, typically two days in length and international in scope. Colloquia are organized by a member of the Academy, often with the assistance of an organizing committee, and feature presentations by leading scientists in the field and discussions with a hundred or more researchers with an interest in the topic. Colloquia presentations are recorded and posted on the National Academy of Sciences Sackler colloquia website and published on CD-ROM. These Colloquia are made possible by a generous gift from Mrs. Jill Sackler, in memory of her husband, Arthur M. Sackler.
Download or read book Environmental and Microbial Relationships written by Irina S. Druzhinina and published by Springer. This book was released on 2016-03-18 with total page 301 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume provides insights into current research on fungal populations, communities and their interactions with other organisms. It focuses on fungal responses to the physical environment; interactions with bacteria, other fungi, invertebrates and plants; the role of fungi in ecosystem processes such as decomposition and nutrient cycling; and aspects of biogeography and conservation. Since the publication of the second edition of Volume IV in 2007, the massive use of “omics” methods has revolutionized our understanding of fungal lifestyles. Highlighting these advances, the third edition has been completely updated and revised. Several chapters deal with various applications of genomics and transcriptomics in biological pest control, as well as interactions with other living systems. This is an invaluable source of information both for scientists who wish to update their knowledge of current advances and for graduate students interested in obtaining a comprehensive introduction to this field of research.
Download or read book Disturbance Effects on Soil Carbon and Greenhouse Gas Emissions in Forest Ecosystems written by Scott X. Chang and published by MDPI. This book was released on 2020-05-23 with total page 232 pages. Available in PDF, EPUB and Kindle. Book excerpt: Forest ecosystems are often disturbed by agents such as harvesting, fire, wind, insects and diseases, and acid deposition, with differing intensities and frequencies. Such disturbances can markedly affect the amount, form, and stability of soil organic carbon in, and the emission of greenhouse gases, including CO2, CH4, and N2O from, forest ecosystems. It is vitally important that we improve our understanding of the impact of different disturbance regimes on forest soil carbon dynamics and greenhouse gas emissions to guide our future research, forest management practices, and policy development. This Special Issue provides an important update on the disturbance effects on soil carbon and greenhouse gas emissions in forest ecosystems in different climate regions.
Download or read book Soil Microbial Responses to Disturbance Events and Consequences for Carbon Cycling in Terrestrial Ecosystems written by Sandra Robin Holden and published by . This book was released on 2014 with total page 189 pages. Available in PDF, EPUB and Kindle. Book excerpt: Understanding the response of soil microbial communities and decomposition to global environmental changes is central to our ability to accurately forecast future terrestrial carbon (C) storage and atmospheric CO2 levels. Increases in the frequency and severity of disturbance events are one element of global change in terrestrial ecosystems. The goal of this dissertation was to measure the response of soil microbial communities and decomposition to disturbance events and to examine the mechanisms underlying post-disturbance changes in decomposition. In the first part of my dissertation work I explored these questions within the context of wildfires in boreal forests. Chapter 1 characterized soil microbial communities and the rate of decomposition across a fire chronosequence in interior Alaska. I found that boreal forest fires reduced soil microbial abundance, altered fungal community composition, and suppressed litter decomposition. Chapter 2 investigated whether soil microbial responses to boreal forest fires differ as a function of fire severity. I demonstrated that higher severity fires elicited greater reductions in soil microbial biomass and larger shifts in fungal community composition than lower severity fires. Chapter 3 tested the mechanisms through which boreal forest fires alter decomposition processes. I discovered that decomposition rates were slower in recently burned forests because of post-fire reductions in soil moisture and C substrate quality. In the second part of my dissertation I expanded my findings to other types of disturbance events using meta-analysis. Chapter 4 reviewed the response of soil microbial biomass to fires. I found that soil microbial biomass was significantly lower in recently burned ecosystems, but the response of microbial biomass to fire differed by fire type and biome. Chapter 5 examined soil microbial responses to abiotic (fire, harvesting, storms) and biotic (insect infestation, pathogen outbreaks) disturbances in forests. I observed that abiotic disturbances significantly reduced soil microbial biomass, while changes in microbial biomass were non-significant following biotic disturbance events. Collectively, these findings suggest that reductions in soil microbial biomass and decomposition rates following abiotic disturbances are likely to slow the transfer of C from soils to the atmosphere and provide a negative feedback to rising atmospheric CO2 concentrations and global change.
Download or read book Disturbance Ecology of Soil Microbial Communities in Response to the Centralia Pa Coal Fire written by Jackson Winther Sorensen and published by . This book was released on 2019 with total page 218 pages. Available in PDF, EPUB and Kindle. Book excerpt: Microbial communities are ubiquitous in our world and play important roles in biogeochemical and ecosystems processes on Earth. The ability of these microbial communities to provide these different processes is frequently tied to their community structure, which can be thought of both in terms of membership (i.e. who is there) and the relative abundance of these members. Changes in environmental conditions often lead to changes in microbial community structure as well. Microbial communities are formed through the process of assembly, which in turn is driven by the four processes of 1) Selection 2) Dispersal 3) Drift and 4) Diversification. Understanding the relative importance of each of these processes in different systems is important for predicting how microbial communities will change in response to disturbances. This dissertation presents work that uses the coal fire in Centralia, PA as a model press disturbance for understanding soil microbial community responses to and recovery from disturbance. The experiments herein aim to shed light the relative roles of Selection, Dispersal, and Drift in governing these responses in soil microbial communities experience a temperature disturbance. An observation study of a chronosequence of fire disturbance in Centralia, PA is used to generate hypotheses as to the relative roles of Selection, Dispersal, and Drift in the assembly of soil microbial communities experiencing a temperature disturbance. Further, an in depth look at some of these communities using shotgun metagenomics is used to observe specific microbial traits and characteristics selected for by the temperature disturbance. Finally, a laboratory soil mesocosm warming experiment investigates the relative influence of Dispersal and dormancy in governing responses to and recovery from disturbance.
Download or read book Dissertation Abstracts International written by and published by . This book was released on 2008 with total page 850 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Jacksonville Harbor Project in Duval County Florida April 2014 written by United States. Office of the Assistant Secretary of the Army (Civil Works) and published by . This book was released on 2015 with total page 1552 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The causes and consequences of microbial community structure written by Diana Reid Nemergut and published by Frontiers E-books. This book was released on 2015-01-22 with total page 185 pages. Available in PDF, EPUB and Kindle. Book excerpt: The causes and consequences of differences in microbial community structure, defined here as the relative proportions of rare and abundant organisms within a community, are poorly understood. Articles in “The Causes and Consequences of Microbial Community Structure”, use empirical or modeling approaches as well as literature reviews to enrich our mechanistic understanding of the controls over the relationship between community structure and ecosystem processes. Specifically, authors address the role of trait distributions and tradeoffs, species-species interactions, evolutionary dynamics, community assembly processes and physical controls in affecting ‘who’s there’ and ‘what they are doing.’
Download or read book Bacterial Communities Under Soil Disturbance from Experimental Mixing in the Lab to Tillage and Bioturbation in the Field written by Jaimie West and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Soil microhabitats are heterogeneous, disconnected, and isolated. Thus, soil supports a vast diversity of microbial inhabitants. How do physical disturbances-which disrupt soil microhabitats-affect bacterial community composition and community assembly processes (e.g., selection and dispersal)? Starting in the lab, we evaluated how bacterial communities are affected by soil mixing at various frequencies over a 16-week incubation. We hypothesized that soil mixing would decrease bacterial richness, and that community assembly would be driven by homogenizing dispersal and homogeneous selection. Using 16S rRNA gene sequencing, we found support for our hypotheses, and results further implied that the vast diversity observed in soil is a direct function of the generally unmixed, isolated nature of microbial communities. When we recapitulated this soil mixing experiment under anoxic conditions, findings corroborated the original study: soil mixing homogenized bacterial communities and increased fast growth potential, regardless of oxygen regime. Further, we found that the static anoxic environment decreased bacterial richness overall, and suppressed the influence of mixing-driven selection relative to the oxic treatment. We then took these fundamental ecological findings at the laboratory-scale, and applied them to field settings in southern Wisconsin under real-world soil mixing mechanisms, evaluating long-term tillage in agricultural soils and earthworm bioturbation in forested soils. With these field experiments, we specifically targeted the effects of disturbance on soil aggregation-which protects soil organic matter and promotes soil carbon persistence-and the bacterial communities that inhabit soil microaggregates. The effects of tillage mirrored those of the lab mixing experiments, resulting in more homogeneous soil bacterial communities, driven by homogenizing dispersal. However, bioturbation and aggregate generation due to the casting activity of non-native earthworms (co-occurring Amynthas tokioensis and A. agrestis) did not consistently impose a strong selective filter on the soil bacterial community. Despite high levels of activity in an otherwise relatively undisturbed forest environment, it does not seem that this earthworm activity necessarily acts to homogenize soil communities via dispersal. Further, we did not identify major distinctions between bacterial communities of the free microaggregate vs. occluded-within-macroaggregate microaggregate fractions in either the agricultural tillage study or the forest earthworm bioturbation study, thus suggesting that soil microaggregates readily shift between these operationally defined fractions, particularly at the end of the agricultural growing season, or in the presence of Amynthas spp. earthworms. With this work, we improve our understanding of the microbial response to soil disturbance, and thus the potential implications of increased soil disturbance under global change.
Download or read book Quantitative Techniques in Participatory Forest Management written by Eugenio Martinez-Falero and published by CRC Press. This book was released on 2016-04-19 with total page 627 pages. Available in PDF, EPUB and Kindle. Book excerpt: Forest management has evolved from a mercantilist view to a multi-functional one that integrates economic, social, and ecological aspects. However, the issue of sustainability is not yet resolved. Quantitative Techniques in Participatory Forest Management brings together global research in three areas of application: inventory of the forest variables that determine the main environmental indices, description and design of new environmental indices, and the application of sustainability indices for regional implementations. All these quantitative techniques create the basis for the development of scientific methodologies of participatory sustainable forest management.
Download or read book Role of Microbial Communities in Mediating Ecosystem Response to Disturbance written by Erica A. H. Smithwick and published by . This book was released on 2006 with total page 383 pages. Available in PDF, EPUB and Kindle. Book excerpt:
