31 results match your criteria ecosystem-scale modeling


Mechanism Across Scales: A Holistic Modeling Framework Integrating Laboratory and Field Studies for Microbial Ecology.

Front Microbiol 2021 24;12:642422. Epub 2021 Mar 24.

Division of Environmental Genomics and Systems Biology, Lawrence Berkeley National Laboratory, Berkeley, CA, United States.

Over the last century, leaps in technology for imaging, sampling, detection, high-throughput sequencing, and -omics analyses have revolutionized microbial ecology to enable rapid acquisition of extensive datasets for microbial communities across the ever-increasing temporal and spatial scales. The present challenge is capitalizing on our enhanced abilities of observation and integrating diverse data types from different scales, resolutions, and disciplines to reach a causal and mechanistic understanding of how microbial communities transform and respond to perturbations in the environment. This type of causal and mechanistic understanding will make predictions of microbial community behavior more robust and actionable in addressing microbially mediated global problems. Read More

View Article and Full-Text PDF

Making 'Chemical Cocktails' - Evolution of Urban Geochemical Processes across the Periodic Table of Elements.

Appl Geochem 2020 Aug;119:1-104632

Department of Geography and Environmental Systems, University of Maryland Baltimore County, 1000 Hilltop Circle, Baltimore, Maryland 21250.

Urbanization contributes to the formation of novel elemental combinations and signatures in terrestrial and aquatic watersheds, also known as 'chemical cocktails.' The composition of chemical cocktails evolves across space and time due to: (1) elevated concentrations from anthropogenic sources, (2) accelerated weathering and corrosion of the built environment, (3) increased drainage density and intensification of urban water conveyance systems, and (4) enhanced rates of geochemical transformations due to changes in temperature, ionic strength, pH, and redox potentials. Characterizing chemical cocktails and underlying geochemical processes is necessary for: (1) tracking pollution sources using complex chemical mixtures instead of individual elements or compounds; (2) developing new strategies for co-managing groups of contaminants; (3) identifying proxies for predicting transport of chemical mixtures using continuous sensor data; and (4) determining whether interactive effects of chemical cocktails produce ecosystem-scale impacts greater than the sum of individual chemical stressors. Read More

View Article and Full-Text PDF

Macrosystems EDDIE teaching modules significantly increase ecology students' proficiency and confidence working with ecosystem models and use of systems thinking.

Ecol Evol 2020 Nov 2;10(22):12515-12527. Epub 2020 Oct 2.

Science Education Resource Center Carleton College Northfield MN USA.

Simulation models are increasingly used by ecologists to study complex, ecosystem-scale phenomena, but integrating ecosystem simulation modeling into ecology undergraduate and graduate curricula remains rare. Engaging ecology students with ecosystem simulation models may enable students to conduct hypothesis-driven scientific inquiry while also promoting their use of systems thinking, but it remains unknown how using hands-on modeling activities in the classroom affects student learning. Here, we developed short (3-hr) teaching modules as part of the Macrosystems EDDIE (Environmental Data-Driven Inquiry & Exploration) program that engage students with hands-on ecosystem modeling in the R statistical environment. Read More

View Article and Full-Text PDF
November 2020

The FLUXNET2015 dataset and the ONEFlux processing pipeline for eddy covariance data.

Authors:
Gilberto Pastorello Carlo Trotta Eleonora Canfora Housen Chu Danielle Christianson You-Wei Cheah Cristina Poindexter Jiquan Chen Abdelrahman Elbashandy Marty Humphrey Peter Isaac Diego Polidori Markus Reichstein Alessio Ribeca Catharine van Ingen Nicolas Vuichard Leiming Zhang Brian Amiro Christof Ammann M Altaf Arain Jonas Ardö Timothy Arkebauer Stefan K Arndt Nicola Arriga Marc Aubinet Mika Aurela Dennis Baldocchi Alan Barr Eric Beamesderfer Luca Belelli Marchesini Onil Bergeron Jason Beringer Christian Bernhofer Daniel Berveiller Dave Billesbach Thomas Andrew Black Peter D Blanken Gil Bohrer Julia Boike Paul V Bolstad Damien Bonal Jean-Marc Bonnefond David R Bowling Rosvel Bracho Jason Brodeur Christian Brümmer Nina Buchmann Benoit Burban Sean P Burns Pauline Buysse Peter Cale Mauro Cavagna Pierre Cellier Shiping Chen Isaac Chini Torben R Christensen James Cleverly Alessio Collalti Claudia Consalvo Bruce D Cook David Cook Carole Coursolle Edoardo Cremonese Peter S Curtis Ettore D'Andrea Humberto da Rocha Xiaoqin Dai Kenneth J Davis Bruno De Cinti Agnes de Grandcourt Anne De Ligne Raimundo C De Oliveira Nicolas Delpierre Ankur R Desai Carlos Marcelo Di Bella Paul di Tommasi Han Dolman Francisco Domingo Gang Dong Sabina Dore Pierpaolo Duce Eric Dufrêne Allison Dunn Jiří Dušek Derek Eamus Uwe Eichelmann Hatim Abdalla M ElKhidir Werner Eugster Cacilia M Ewenz Brent Ewers Daniela Famulari Silvano Fares Iris Feigenwinter Andrew Feitz Rasmus Fensholt Gianluca Filippa Marc Fischer John Frank Marta Galvagno Mana Gharun Damiano Gianelle Bert Gielen Beniamino Gioli Anatoly Gitelson Ignacio Goded Mathias Goeckede Allen H Goldstein Christopher M Gough Michael L Goulden Alexander Graf Anne Griebel Carsten Gruening Thomas Grünwald Albin Hammerle Shijie Han Xingguo Han Birger Ulf Hansen Chad Hanson Juha Hatakka Yongtao He Markus Hehn Bernard Heinesch Nina Hinko-Najera Lukas Hörtnagl Lindsay Hutley Andreas Ibrom Hiroki Ikawa Marcin Jackowicz-Korczynski Dalibor Janouš Wilma Jans Rachhpal Jassal Shicheng Jiang Tomomichi Kato Myroslava Khomik Janina Klatt Alexander Knohl Sara Knox Hideki Kobayashi Georgia Koerber Olaf Kolle Yoshiko Kosugi Ayumi Kotani Andrew Kowalski Bart Kruijt Julia Kurbatova Werner L Kutsch Hyojung Kwon Samuli Launiainen Tuomas Laurila Bev Law Ray Leuning Yingnian Li Michael Liddell Jean-Marc Limousin Marryanna Lion Adam J Liska Annalea Lohila Ana López-Ballesteros Efrén López-Blanco Benjamin Loubet Denis Loustau Antje Lucas-Moffat Johannes Lüers Siyan Ma Craig Macfarlane Vincenzo Magliulo Regine Maier Ivan Mammarella Giovanni Manca Barbara Marcolla Hank A Margolis Serena Marras William Massman Mikhail Mastepanov Roser Matamala Jaclyn Hatala Matthes Francesco Mazzenga Harry McCaughey Ian McHugh Andrew M S McMillan Lutz Merbold Wayne Meyer Tilden Meyers Scott D Miller Stefano Minerbi Uta Moderow Russell K Monson Leonardo Montagnani Caitlin E Moore Eddy Moors Virginie Moreaux Christine Moureaux J William Munger Taro Nakai Johan Neirynck Zoran Nesic Giacomo Nicolini Asko Noormets Matthew Northwood Marcelo Nosetto Yann Nouvellon Kimberly Novick Walter Oechel Jørgen Eivind Olesen Jean-Marc Ourcival Shirley A Papuga Frans-Jan Parmentier Eugenie Paul-Limoges Marian Pavelka Matthias Peichl Elise Pendall Richard P Phillips Kim Pilegaard Norbert Pirk Gabriela Posse Thomas Powell Heiko Prasse Suzanne M Prober Serge Rambal Üllar Rannik Naama Raz-Yaseef Corinna Rebmann David Reed Victor Resco de Dios Natalia Restrepo-Coupe Borja R Reverter Marilyn Roland Simone Sabbatini Torsten Sachs Scott R Saleska Enrique P Sánchez-Cañete Zulia M Sanchez-Mejia Hans Peter Schmid Marius Schmidt Karl Schneider Frederik Schrader Ivan Schroder Russell L Scott Pavel Sedlák Penélope Serrano-Ortíz Changliang Shao Peili Shi Ivan Shironya Lukas Siebicke Ladislav Šigut Richard Silberstein Costantino Sirca Donatella Spano Rainer Steinbrecher Robert M Stevens Cove Sturtevant Andy Suyker Torbern Tagesson Satoru Takanashi Yanhong Tang Nigel Tapper Jonathan Thom Michele Tomassucci Juha-Pekka Tuovinen Shawn Urbanski Riccardo Valentini Michiel van der Molen Eva van Gorsel Ko van Huissteden Andrej Varlagin Joseph Verfaillie Timo Vesala Caroline Vincke Domenico Vitale Natalia Vygodskaya Jeffrey P Walker Elizabeth Walter-Shea Huimin Wang Robin Weber Sebastian Westermann Christian Wille Steven Wofsy Georg Wohlfahrt Sebastian Wolf William Woodgate Yuelin Li Roberto Zampedri Junhui Zhang Guoyi Zhou Donatella Zona Deb Agarwal Sebastien Biraud Margaret Torn Dario Papale

Sci Data 2020 07 9;7(1):225. Epub 2020 Jul 9.

DIBAF, University of Tuscia, Viterbo, 01100, Italy.

The FLUXNET2015 dataset provides ecosystem-scale data on CO, water, and energy exchange between the biosphere and the atmosphere, and other meteorological and biological measurements, from 212 sites around the globe (over 1500 site-years, up to and including year 2014). These sites, independently managed and operated, voluntarily contributed their data to create global datasets. Data were quality controlled and processed using uniform methods, to improve consistency and intercomparability across sites. Read More

View Article and Full-Text PDF

Molybdenum threshold for ecosystem scale alternative vanadium nitrogenase activity in boreal forests.

Proc Natl Acad Sci U S A 2019 12 14;116(49):24682-24688. Epub 2019 Nov 14.

Department of Geosciences, Princeton University, Princeton, NJ 08544.

Biological nitrogen fixation (BNF) by microorganisms associated with cryptogamic covers, such as cyanolichens and bryophytes, is a primary source of fixed nitrogen in pristine, high-latitude ecosystems. On land, low molybdenum (Mo) availability has been shown to limit BNF by the most common form of nitrogenase (Nase), which requires Mo in its active site. Vanadium (V) and iron-only Nases have been suggested as viable alternatives to countering Mo limitation of BNF; however, field data supporting this long-standing hypothesis have been lacking. Read More

View Article and Full-Text PDF
December 2019

Refining the role of phenology in regulating gross ecosystem productivity across European peatlands.

Glob Chang Biol 2020 02 3;26(2):876-887. Epub 2019 Dec 3.

Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, Umeå, Sweden.

The role of plant phenology as a regulator for gross ecosystem productivity (GEP) in peatlands is empirically not well constrained. This is because proxies to track vegetation development with daily coverage at the ecosystem scale have only recently become available and the lack of such data has hampered the disentangling of biotic and abiotic effects. This study aimed at unraveling the mechanisms that regulate the seasonal variation in GEP across a network of eight European peatlands. Read More

View Article and Full-Text PDF
February 2020

Coinfection Organizes Epidemiological Networks of Viruses and Hosts and Reveals Hubs of Transmission.

Phytopathology 2019 Jun 22;109(6):1003-1010. Epub 2019 Apr 22.

Centro de Biotecnología y Genómica de Plantas Universidad Politécnica de Madrid (UPM)-Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA) and Escuela Técnica Superior de Ingeniería Agronómica, Alimentaria y de Biosistemas, Universidad Politécnica de Madrid, Madrid 28223, Spain.

Multiple virus infections affect the competence of host plants to transmit disease. The effects of coinfection on transmission are expected to produce ecologically complex pathogen and host-pathogen interactions. However, the prediction of disease risk will rely on untangling nonrandom from random patterns of infection to identify underlying processes that drive these interactions. Read More

View Article and Full-Text PDF

Role of Shellfish Aquaculture in the Reduction of Eutrophication in an Urban Estuary.

Environ Sci Technol 2018 01 15;52(1):173-183. Epub 2017 Dec 15.

Environmental Protection Agency Long Island Sound Office, Government Center , Suite 9-11, 888 Washington Blvd., Stamford, Connecticut 06904-2152, United States.

Land-based management has reduced nutrient discharges; however, many coastal waterbodies remain impaired. Oyster "bioextraction" of nutrients and how oyster aquaculture might complement existing management measures in urban estuaries was examined in Long Island Sound, Connecticut. Eutrophication status, nutrient removal, and ecosystem service values were estimated using eutrophication, circulation, local- and ecosystem-scale models, and an avoided-costs valuation. Read More

View Article and Full-Text PDF
January 2018

Dynamic Carboniferous tropical forests: new views of plant function and potential for physiological forcing of climate.

New Phytol 2017 Sep 25;215(4):1333-1353. Epub 2017 Jul 25.

Center for Integrative Geosciences, University of Connecticut, Storrs, CT, 06269, USA.

Contents 1333 I. 1334 II. 1335 III. Read More

View Article and Full-Text PDF
September 2017

A multi-objective constraint-based approach for modeling genome-scale microbial ecosystems.

PLoS One 2017 10;12(2):e0171744. Epub 2017 Feb 10.

Computational Biology group, LINA UMR 6241 CNRS, EMN, Université de Nantes, Nantes, France.

Interplay within microbial communities impacts ecosystems on several scales, and elucidation of the consequent effects is a difficult task in ecology. In particular, the integration of genome-scale data within quantitative models of microbial ecosystems remains elusive. This study advocates the use of constraint-based modeling to build predictive models from recent high-resolution -omics datasets. Read More

View Article and Full-Text PDF

Impact of Leaf Traits on Temporal Dynamics of Transpired Oxygen Isotope Signatures and Its Impact on Atmospheric Vapor.

Front Plant Sci 2017 18;8. Epub 2017 Jan 18.

Ecosystem Physiology, University Freiburg Freiburg, Germany.

Oxygen isotope signatures of transpiration (δ ) are powerful tracers of water movement from plant to global scale. However, a mechanistic understanding of how leaf morphological/physiological traits effect δ is missing. A laser spectrometer was coupled to a leaf-level gas-exchange system to measure fluxes and isotopic signatures of plant transpiration under controlled conditions in seven distinct species (). Read More

View Article and Full-Text PDF
January 2017

Do the energy fluxes and surface conductance of boreal coniferous forests in Europe scale with leaf area?

Glob Chang Biol 2016 12 13;22(12):4096-4113. Epub 2016 Oct 13.

Department of Physics, University of Helsinki, PO Box 64, 00140 University of Helsinki, Finland.

Earth observing systems are now routinely used to infer leaf area index (LAI) given its significance in spatial aggregation of land surface fluxes. Whether LAI is an appropriate scaling parameter for daytime growing season energy budget, surface conductance (G ), water- and light-use efficiency and surface-atmosphere coupling of European boreal coniferous forests was explored using eddy-covariance (EC) energy and CO fluxes. The observed scaling relations were then explained using a biophysical multilayer soil-vegetation-atmosphere transfer model as well as by a bulk G representation. Read More

View Article and Full-Text PDF
December 2016

Considerations of Environmentally Relevant Test Conditions for Improved Evaluation of Ecological Hazards of Engineered Nanomaterials.

Environ Sci Technol 2016 06 3;50(12):6124-45. Epub 2016 Jun 3.

University of California Center for Environmental Implications of Nanotechnology (UC CEIN), University of California , Los Angeles, California 90095, United States.

Engineered nanomaterials (ENMs) are increasingly entering the environment with uncertain consequences including potential ecological effects. Various research communities view differently whether ecotoxicological testing of ENMs should be conducted using environmentally relevant concentrations-where observing outcomes is difficult-versus higher ENM doses, where responses are observable. What exposure conditions are typically used in assessing ENM hazards to populations? What conditions are used to test ecosystem-scale hazards? What is known regarding actual ENMs in the environment, via measurements or modeling simulations? How should exposure conditions, ENM transformation, dose, and body burden be used in interpreting biological and computational findings for assessing risks? These questions were addressed in the context of this critical review. Read More

View Article and Full-Text PDF

[Land use and land cover charnge (LUCC) and landscape service: Evaluation, mapping and modeling].

Ying Yong Sheng Tai Xue Bao 2015 May;26(5):1594-600

Studies on ecosystem service from landscape scale aspect have received increasing attention from researchers all over the world. Compared with ecosystem scale, it should be more suitable to explore the influence of human activities on land use and land cover change (LUCC), and to interpret the mechanisms and processes of sustainable landscape dynamics on landscape scale. Based on comprehensive and systematic analysis of researches on landscape service, this paper firstly discussed basic concepts and classification of landscape service. Read More

View Article and Full-Text PDF

Modeling elephant-mediated cascading effects of water point closure.

Ecol Appl 2015 Mar;25(2):402-15

Wildlife management to reduce the impact of wildlife on their habitat can be done in several ways, among which removing animals (by either culling or translocation) is most often used. There are, however, alternative ways to control wildlife densities, such as opening or closing water points. The effects of these alternatives are poorly studied. Read More

View Article and Full-Text PDF

Ecosystem-scale volatile organic compound fluxes during an extreme drought in a broadleaf temperate forest of the Missouri Ozarks (central USA).

Glob Chang Biol 2015 Oct 7;21(10):3657-74. Epub 2015 Jul 7.

Department of Earth System Science, University of California, Irvine, CA, 92697, USA.

Considerable amounts and varieties of biogenic volatile organic compounds (BVOCs) are exchanged between vegetation and the surrounding air. These BVOCs play key ecological and atmospheric roles that must be adequately represented for accurately modeling the coupled biosphere-atmosphere-climate earth system. One key uncertainty in existing models is the response of BVOC fluxes to an important global change process: drought. Read More

View Article and Full-Text PDF
October 2015

Modeling the direct and indirect effects of copper on phytoplankton-zooplankton interactions.

Aquat Toxicol 2015 May 7;162:73-81. Epub 2015 Mar 7.

Laboratoire Ecologie, Systématique et Evolution, UMR 8079, Univ. Paris-Sud Bât. 362, 91405 Orsay Cedex, France.

Predicting the effects of pollution at the community level is difficult because of the complex impacts of ecosystem dynamics and properties. To predict the effects of copper on a plant-herbivore interaction in a freshwater ecosystem, we built a model that focuses on the interaction between an alga, Scenedesmus sp., and a herbivore, Daphnia sp. Read More

View Article and Full-Text PDF

Modeling food web structure and selenium biomagnification in Lake Macquarie, New South Wales, Australia, using stable carbon and nitrogen isotopes.

Environ Toxicol Chem 2015 Mar 6;34(3):608-17. Epub 2015 Feb 6.

Institute for Applied Ecology, University of Canberra, Canberra, Australian Capital Territory, Australia; Archaeology and Natural History, College of Asia and the Pacific, The Australian National University, Canberra, Australian Capital Territory, Australia.

As a consequence of coal-fired power station operations, elevated selenium concentrations have been reported in the sediments and biota of Lake Macquarie (New South Wales, Australia). In the present study, an ecosystem-scale model has been applied to determine how selenium in a seagrass food web is processed from sediments and water through diet to predators, using stable isotopes (δ(13) C and δ(15) N) to establish the trophic position of organisms. Trophic position, habitat, and feeding zone were examined as possible factors influencing selenium bioaccumulation. Read More

View Article and Full-Text PDF

Completing the FACE of elevated CO₂ research.

Environ Int 2014 Dec 28;73:252-8. Epub 2014 Aug 28.

Institute of Biological Environmental and Rural Sciences, Aberystwyth University, Ceredigion, SY23 3DA, Wales, UK. Electronic address:

We appraise the present geographical extent and inherent knowledge limits, following two decades of research on elevated CO2 responses in plant communities, and ask whether such research has answered the key question in quantifying the limits of compensatory CO2 uptake in the major biomes. Our synthesis of all ecosystem-scale (between 10 m(2) and 3000 m(2) total experimental plot area) elevated CO2 (eCO2) experiments in natural ecosystems conducted worldwide since 1987 (n=151) demonstrates that the locations of these eCO2 experiments have been spatially biased, targeting primarily the temperate ecosystems of northern America and Europe. We consider the consequences, suggesting fundamentally that this limits the capacity of the research to understand how the world's major plant communities will respond to eCO2. Read More

View Article and Full-Text PDF
December 2014

Forest response and recovery following disturbance in upland forests of the Atlantic Coastal Plain.

Front Plant Sci 2014 26;5:294. Epub 2014 Jun 26.

Department of Biology and Molecular Biology, Montclair State University Montclair, NJ, USA.

Carbon and water cycling of forests contribute significantly to the Earth's overall biogeochemical cycling and may be affected by disturbance and climate change. As a larger body of research becomes available about leaf-level, ecosystem and regional scale effects of disturbances on forest ecosystems, a more mechanistic understanding is developing which can improve modeling efforts. Here, we summarize some of the major effects of physical and biogenic disturbances, such as drought, prescribed fire, and insect defoliation, on leaf and ecosystem-scale physiological responses as well as impacts on carbon and water cycling in an Atlantic Coastal Plain upland oak/pine and upland pine forest. Read More

View Article and Full-Text PDF

Sources and sinks of carbonyl sulfide in an agricultural field in the Southern Great Plains.

Proc Natl Acad Sci U S A 2014 Jun 9;111(25):9064-9. Epub 2014 Jun 9.

Institute of Ecology and Environmental Sciences, Université Pierre et Marie Curie, Grignon Campus, 78850 Thiverval-Grignon, France;Department of Atmospheric and Oceanic Sciences, University of California, Los Angeles, CA 90095

Net photosynthesis is the largest single flux in the global carbon cycle, but controls over its variability are poorly understood because there is no direct way of measuring it at the ecosystem scale. We report observations of ecosystem carbonyl sulfide (COS) and CO2 fluxes that resolve key gaps in an emerging framework for using concurrent COS and CO2 measurements to quantify terrestrial gross primary productivity. At a wheat field in Oklahoma we found that in the peak growing season the flux-weighted leaf relative uptake of COS and CO2 during photosynthesis was 1. Read More

View Article and Full-Text PDF

On the persistence of memory: soft clocks and terrestrial biosphere-atmosphere interactions.

Plant Signal Behav 2013 Nov 3;8(11):e26964. Epub 2013 Dec 3.

Hawkesbury Institute for the Environment; University of Western Sydney; Richmond, NSW Australia.

The circadian clock is considered a central "orchestrator" of gene expression and metabolism. Concomitantly, the circadian clock is considered of negligible influence in the field and beyond leaf levels, where direct physiological responses to environmental cues are considered the main drivers of diel fluctuations. I propose to bridge the gap across scales by examining current evidence on whether circadian rhythmicity in gas exchange is relevant for field settings and at the ecosystem scale. Read More

View Article and Full-Text PDF
November 2013

Experimental vs. modeled water use in mature Norway spruce (Picea abies) exposed to elevated CO(2).

Front Plant Sci 2012 16;3:229. Epub 2012 Oct 16.

School of Applied Sciences, Auckland University of Technology Auckland, New Zealand ; Forest Ecology, ETH Zurich Zurich, Switzerland ; Institute of Botany, University of Basel Basel, Switzerland.

Rising levels of atmospheric CO(2) have often been reported to reduce plant water use. Such behavior is also predicted by standard equations relating photosynthesis, stomatal conductance, and atmospheric CO(2) concentration, which form the core of dynamic global vegetation models (DGVMs). Here, we provide first results from a free air CO(2) enrichment (FACE) experiment with naturally growing, mature (35 m) Picea abies (L. Read More

View Article and Full-Text PDF
October 2012

A methodology for ecosystem-scale modeling of selenium.

Integr Environ Assess Manag 2010 Oct;6(4):685-710

US Geological Survey, Menlo Park, California 94025, USA.

The main route of exposure for selenium (Se) is dietary, yet regulations lack biologically based protocols for evaluations of risk. We propose here an ecosystem-scale model that conceptualizes and quantifies the variables that determine how Se is processed from water through diet to predators. This approach uses biogeochemical and physiological factors from laboratory and field studies and considers loading, speciation, transformation to particulate material, bioavailability, bioaccumulation in invertebrates, and trophic transfer to predators. Read More

View Article and Full-Text PDF
October 2010

Modeling whole-tree carbon assimilation rate using observed transpiration rates and needle sugar carbon isotope ratios.

New Phytol 2010 Mar 19;185(4):1000-15. Epub 2010 Jan 19.

Department of Ecology and Evolutionary Biology, University of Colorado, Boulder, CO 80309, USA.

*Understanding controls over plant-atmosphere CO(2) exchange is important for quantifying carbon budgets across a range of spatial and temporal scales. In this study, we used a simple approach to estimate whole-tree CO(2) assimilation rate (A(Tree)) in a subalpine forest ecosystem. *We analysed the carbon isotope ratio (delta(13)C) of extracted needle sugars and combined it with the daytime leaf-to-air vapor pressure deficit to estimate tree water-use efficiency (WUE). Read More

View Article and Full-Text PDF

Complexity in water and carbon dioxide fluxes following rain pulses in an African savanna.

Oecologia 2009 Sep 7;161(3):469-80. Epub 2009 Jul 7.

Graduate School of Geography, Clark University, 950 Main Street, Worcester, MA 01610, USA.

The idea that many processes in arid and semi-arid ecosystems are dormant until activated by a pulse of rainfall, and then decay from a maximum rate as the soil dries, is widely used as a conceptual and mathematical model, but has rarely been evaluated with data. This paper examines soil water, evapotranspiration (ET), and net ecosystem CO2 exchange measured for 5 years at an eddy covariance tower sited in an Acacia-Combretum savanna near Skukuza in the Kruger National Park, South Africa. The analysis characterizes ecosystem flux responses to discrete rain events and evaluates the skill of increasingly complex "pulse models". Read More

View Article and Full-Text PDF
September 2009

Application of ecosystem-scale fate and bioaccumulation models to predict fish mercury response times to changes in atmospheric deposition.

Environ Toxicol Chem 2009 Apr;28(4):881-93

U.S. Environmental Protection Agency, Office of Research and Development, Ecosystem Research Division, 960 College Station Road, Athens, Georgia 30605, USA.

Management strategies for controlling anthropogenic mercury emissions require understanding how ecosystems will respond to changes in atmospheric mercury deposition. Process-based mathematical models are valuable tools for informing such decisions, because measurement data often are sparse and cannot be extrapolated to investigate the environmental impacts of different policy options. Here, we bring together previously developed and evaluated modeling frameworks for watersheds, water bodies, and food web bioaccumulation of mercury. Read More

View Article and Full-Text PDF

Effect of eutrophication upon radionuclide dynamics in the Sacca di Goro lagoon (Po River Delta, Italy): a combined field, experimental and modeling study.

Environ Pollut 2003 ;125(3):433-46

Department of Environmental Sciences, University of Parma, Parco Area delle Scienze, Italy.

The focus of this paper is on the relationship between eutrophication and radionuclide circulation at the whole ecosystem scale in the shallow estuarine environment of the Sacca di Goro (Po River Delta, Italy). This lagoon is frequently affected by dystrophic crises, due to decomposition of huge amounts of macroalgae (mainly Ulva rigida), and critical conditions created at the interface between sediment and water are such that Cs-137 accumulated in the sediment can be mobilized and made available in the water column. The release of cesium from sediment in this ecosystem has been evaluated through a field experiment in which chemical conditions typical of anoxic crises were artificially created in enclosures. Read More

View Article and Full-Text PDF
November 2003

Measuring and modeling conductances of black spruce at three organizational scales: shoot, branch and canopy.

Tree Physiol 2000 Jun;20(11):713-723

IERM, University of Edinburgh, Edinburgh EH9 3JU, U.K.

To investigate the extent to which the energy balance of a globally important ecosystem is controlled by biological and environmental processes, measurements of water vapor flux were made on individual black spruce (Picea mariana [Mill.] B.S. Read More

View Article and Full-Text PDF

Plant ecophysiology and forest response to global change.

Authors:
N Buchmann

Tree Physiol 2002 Nov;22(15-16):1177-84

Max-Planck-Institut für Biogeochemie, P.O. Box 10 01 64, D-07701 Jena, Germany.

There are many ways of studying forest responses to global change. Most current national and international programs focus on net gas exchange of the terrestrial biosphere and are typically interdisciplinary, multi-scale projects. Key objectives of these programs are surprisingly similar to those of classical plant ecophysiology studies, i. Read More

View Article and Full-Text PDF
November 2002