Nitrogen Dynamics in Woody Plant Ecosystems PDF Download

Author: Richard Douglas Smith
Publisher:
ISBN:
Category :
Languages : en
Pages : 200

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Author: Julia Den-Yue Liao
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Woody plant invasion of grasslands is prevalent worldwide, but the biogeochemical consequences of this vegetation shift remain largely unquantified. In the Rio Grande Plains, TX, grasslands and savannas dominated by C4 grasses have undergone succession over the past century to subtropical thorn woodlands dominated by C3 trees/shrubs. To elucidate mechanisms of soil organic carbon (SOC) and soil total N (STN) storage and dynamics in this ecosystem, I measured the mass and isotopic composition ([o] 13C, 15N) of C and N in whole-soil and soil size/density fractions in chronosequences consisting of remnant grasslands (Time 0) and woody plant stands ranging in age from 10-130 years. Rates of SOC and STN storage averaged 10-30 g C m−2yr−1 and 1-3 g N m−2yr−1, respectively. These accumulation rates increased soil C and N pools 80-200% following woody encroachment. Soil microbial biomass (SMB-C) also increased after woody invasion. Decreasing C[subscript]mic/C [subscript]org and higher qCO2 in woodlands relative to grasslands suggests that woody litter is of poorer quality than grassland litter. Greater SOC and STN following woody invasion may also be due to increased protection of organic matter by stable soil structure. Soil aggregation increased following woody ; however, most of the C and N accumulated in free particulate organic matter (POM) fractions not protected within aggregates. Mean residence times (MRTs) of soil fractions were calculated based on changes in their [o]13C with time after woody encroachment. Free POM had the shortest average MRTs (30 years) and silt+clay the longest (360 years). Fine POM had MRTs of about 60 years, reflecting protection by location within aggregates. [o]15N values of soil fractions were positively correlated with their MRTs, suggesting that higher [o]15N values reflect an increased degree of humification. Increases in SOC and STN are probably being sustained by greater inputs, slower turnover of POM (some biochemical recalcitrance), and protection of organic matter in aggregates and association with silt and clay. Grassland-to-woodland conversion during the past century has been geographically extensive in grassland ecosystems worldwide, suggesting that changes in soil C and N dynamics and storage documented here could have significance for global C and N cycles.

Author: David Tilman
Publisher: Princeton University Press
ISBN: 0691209596
Category : Science
Languages : en
Pages : 376

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Although ecologists have long considered morphology and life history to be important determinants of the distribution, abundance, and dynamics of plants in nature, this book contains the first theory to predict explicitly both the evolution of plant traits and the effects of these traits on plant community structure and dynamics. David Tilman focuses on the universal requirement of terrestrial plants for both below-ground and above-ground resources. The physical separation of these resources means that plants face an unavoidable tradeoff. To obtain a higher proportion of one resource, a plant must allocate more of its growth to the structures involved in its acquisition, and thus necessarily obtain a lower proportion of another resource. Professor Tilman presents a simple theory that includes this constraint and tradeoff, and uses the theory to explore the evolution of plant life histories and morphologies along productivity and disturbance gradients. The book shows that relative growth rate, which is predicted to be strongly influenced by a plant's proportional allocation to leaves, is a major determinant of the transient dynamics of competition. These dynamics may explain the differences between successions on poor versus rich soils and suggest that most field experiments performed to date have been of too short a duration to allow unambiguous interpretation of their results.

Author: Rattan Lal
Publisher: CRC Press
ISBN: 1351415751
Category : Technology & Engineering
Languages : en
Pages : 632

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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.

Author: David D. Briske
Publisher: Springer
ISBN: 3319467093
Category : Technology & Engineering
Languages : en
Pages : 664

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This book is open access under a CC BY-NC 2.5 license. This book provides an unprecedented synthesis of the current status of scientific and management knowledge regarding global rangelands and the major challenges that confront them. It has been organized around three major themes. The first summarizes the conceptual advances that have occurred in the rangeland profession. The second addresses the implications of these conceptual advances to management and policy. The third assesses several major challenges confronting global rangelands in the 21st century. This book will compliment applied range management textbooks by describing the conceptual foundation on which the rangeland profession is based. It has been written to be accessible to a broad audience, including ecosystem managers, educators, students and policy makers. The content is founded on the collective experience, knowledge and commitment of 80 authors who have worked in rangelands throughout the world. Their collective contributions indicate that a more comprehensive framework is necessary to address the complex challenges confronting global rangelands. Rangelands represent adaptive social-ecological systems, in which societal values, organizations and capacities are of equal importance to, and interact with, those of ecological processes. A more comprehensive framework for rangeland systems may enable management agencies, and educational, research and policy making organizations to more effectively assess complex problems and develop appropriate solutions.

Author: Mark A. Sutton
Publisher: Cambridge University Press
ISBN: 1139501372
Category : Science
Languages : en
Pages : 665

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Presenting the first continental-scale assessment of reactive nitrogen in the environment, this book sets the related environmental problems in context by providing a multidisciplinary introduction to the nitrogen cycle processes. Issues of upscaling from farm plot and city to national and continental scales are addressed in detail with emphasis on opportunities for better management at local to global levels. The five key societal threats posed by reactive nitrogen are assessed, providing a framework for joined-up management of the nitrogen cycle in Europe, including the first cost-benefit analysis for different reactive nitrogen forms and future scenarios. Incorporating comprehensive maps, a handy technical synopsis and a summary for policy makers, this landmark volume is an essential reference for academic researchers across a wide range of disciplines, as well as stakeholders and policy makers. It is also a valuable tool in communicating the key environmental issues and future challenges to the wider public.

Author: Stefan Schmutz
Publisher: Springer
ISBN: 3319732501
Category : Science
Languages : en
Pages : 562

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This open access book surveys the frontier of scientific river research and provides examples to guide management towards a sustainable future of riverine ecosystems. Principal structures and functions of the biogeosphere of rivers are explained; key threats are identified, and effective solutions for restoration and mitigation are provided. Rivers are among the most threatened ecosystems of the world. They increasingly suffer from pollution, water abstraction, river channelisation and damming. Fundamental knowledge of ecosystem structure and function is necessary to understand how human acitivities interfere with natural processes and which interventions are feasible to rectify this. Modern water legislation strives for sustainable water resource management and protection of important habitats and species. However, decision makers would benefit from more profound understanding of ecosystem degradation processes and of innovative methodologies and tools for efficient mitigation and restoration. The book provides best-practice examples of sustainable river management from on-site studies, European-wide analyses and case studies from other parts of the world. This book will be of interest to researchers in the field of aquatic ecology, river system functioning, conservation and restoration, to postgraduate students, to institutions involved in water management, and to water related industries.

Author: Mary Ann Topa
Publisher:
ISBN:
Category :
Languages : en
Pages : 266

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Author: Peter Frank Scogings
Publisher: John Wiley & Sons
ISBN: 1119081106
Category : Science
Languages : en
Pages : 794

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Insights on current research and recent developments in understanding global savanna systems Increasingly recognized as synonymous with tropical grassy biomes, savannas are found in tropical and sub-tropical climates as well as warm, temperate regions of North America. Savanna Woody Plants and Large Herbivores examines the interactions between woody plants and browsing mammals in global savannas—focusing primarily on the C4 grassy ecosystems with woody components that constitute the majority of global savannas—and discusses contemporary savanna management models and applications. This much-needed addition to current research examines topics including the varying behavior of browsing mammals, the response to browsing by woody species, and the factors that inhibit forage intake. Contributions from an international team of active researchers and experts compare and contrast different savanna ecosystems, offering a global perspective on savanna functioning, the roles of soil and climate in resource availability and organism interaction, and the possible impacts of climate change across global savannas. Fills a gap in literature on savanna management issues, including biodiversity conservation and animal production Applies concepts developed in other biomes to future savanna research Complements contemporary books on savanna or large herbivore ecology Focuses on the woody component of savanna ecosystems and large herbivore interactions in savannas Compares tree-mammal systems of savannas and other eco-systems of temperate and boreal regions Provides numerous case studies of plant-mammal interactions from various savanna ecosystems Savanna Woody Plants and Large Herbivores is a valuable addition to those in fields such as ecology, wildlife and conservation biology, natural resource management, and environmental science.

Author: Zahid Javid
Publisher:
ISBN:
Category : Forest ecology
Languages : en
Pages : 170

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