Suchergebnisse

Intro -- Biogeochemistry: An Analysis of Global Change -- Copyright -- Dedication -- Contents -- Preface -- Acknowledgments -- Part I: Processes and reactions -- Chapter 1: Introduction -- What is biogeochemistry? -- Understanding the earth as a chemical system -- Perturbations of the steady-state -- Large-scale experiments -- Scales of endeavor -- Thermodynamics -- Stoichiometry -- Lovelock's Gaia -- Chapter 2: Origins -- Introduction -- Origins of the elements -- Origin of the solar system and the solid earth -- Origin of the atmosphere and the oceans -- Origin of life -- Evolution of metabolic pathways -- Photosynthesis: The origin of oxygen on earth -- Chemoautotrophy -- Anaerobic respiration in an aerobic world -- Comparative planetary history: Earth, Mars, and Venus -- Mars -- Venus -- Moons and exoplanets -- Summary -- Chapter 3: The Atmosphere -- Introduction -- Structure and circulation -- Atmospheric composition -- Gases -- Aerosols -- Biogeochemical reactions in the troposphere -- Major constituents-Nitrogen -- Oxygen -- Carbon dioxide -- Trace biogenic gases -- Oxidation reactions in the atmosphere -- Atmospheric deposition -- Processes -- Regional patterns and trends -- Biogeochemical reactions in the stratosphere -- Ozone -- Stratospheric sulfur compounds -- Models of the atmosphere and global climate -- Summary -- Chapter 4: The Lithosphere -- Introduction -- Rock weathering -- Chemical weathering -- Secondary minerals -- Soil chemical reactions -- Cation exchange capacity -- Soil buffering -- Anion adsorption capacity -- Phosphorus minerals -- Soil development -- Forests -- Grasslands -- Deserts -- Models of soil development -- Weathering rates -- Chemical weathering rates -- Mechanical weathering -- Total denudation rates -- Summary -- Chapter 5: The Carbon Cycle of Terrestrial Ecosystems -- Introduction -- Photosynthesis.

The Hubbard Brook Experimental Forest (HBEF) was established in 1955 by the U.S. Department of Agriculture, Forest Service out of concerns about the effects of logging increasing flooding and erosion. To address this issue, within the HBEF hydrological and micrometeorological monitoring was initiated in small watersheds designated for harvesting experiments. The Hubbard Brook Ecosystem Study (HBES) originated in 1963, with the idea of using the small watershed approach to study element fluxes and cycling and the response of forest ecosystems to disturbances, such as forest management practices and air pollution. Early evidence of acid rain was documented at the HBEF and research by scientists at the site helped shape acid rain mitigation policies. New lines of investigation at the HBEF have built on the long legacy of watershed research resulting in a shift from comparing inputs and outputs and quantifying pools and fluxes to a more mechanistic understanding of ecosystem processes within watersheds. For example, hydropedological studies have shed light on linkages between hydrologic flow paths and soil development that provide valuable perspective for managing forests and understanding stream water quality. New high frequency in situ stream chemistry sensors are providing insights about extreme events and diurnal patterns that were indiscernible with traditional weekly sampling. Additionally, tools are being developed for visual and auditory data exploration and discovery by a broad audience. Given the unprecedented environmental change that is occurring, data from the small watersheds at the HBEF are more relevant now than ever and will continue to serve as a basis for sound environmental decision-making. ; Public domain authored by a U.S. government employee

Quantitative models are crucial to almost every area of ecosystem science. They provide a logical structure that guides and informs empirical observations of ecosystem processes. They play a particularly crucial role in synthesizing and integrating our understanding of the immense diversity of ecosystem structure and function. Increasingly, models are being called on to predict the effects of human actions on natural ecosystems. Despite the widespread use of models, there exists intense debate within the field over a wide range of practical and philosophical issues pertaining to quantitative modeling. This book--which grew out of a gathering of leading experts at the ninth Cary Conference--explores those issues. The book opens with an overview of the status and role of modeling in ecosystem science, including perspectives on the long-running debate over the appropriate level of complexity in models. This is followed by eight chapters that address the critical issue of evaluating ecosystem models, including methods of addressing uncertainty. Next come several case studies of the role of models in environmental policy and management. A section on the future of modeling in ecosystem science focuses on increasing the use of modeling in undergraduate education and the modeling skills of professionals within the field. The benefits and limitations of predictive (versus observational) models are also considered in detail. Written by stellar contributors, this book grants access to the state of the art and science of ecosystem modeling