LEARN: Land EcosystemAtmosphere Reactive Nitrogen

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LEARN Land Ecosystem-Atmosphere Reactive
Nitrogen A Proposed Project for
iLEAPS Mary Anne Carroll,
Coordinator iLEAPS Science Steering Committee
Meeting Vienna, Austria April 30, 2005
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MOTIVATION
Haber-Bosch process invented

• Changes in N fluxes of reactive, or biologically
  available N.
• (b) Simultaneous increases in atmospheric N2O and
  increased manure production as a result of
  reactive N generation in (a).

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SPATIAL PATTERNS OF TOTAL INORGANIC NITROGEN
DEPOSITION
MOTIVATION
F.J. Detener
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MOTIVATION
Figure by A. J. Hogg
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A schematic of the "life-cycle" of gas-phase
nitrogen including dominant emissions sources,
tropospheric transformations, role in the overall
nitrogen cycle, and important linkages to the
carbon cycle.
MOTIVATION
(Shepson, Bertman, Sparks, and Carroll, 2002)
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Building on a recent community workshop
http//www.acd.ucar.edu/oppFund/BGS/ and link on
iLEAPS web page
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LEARN Proposed Steering Committee Claus Beier,
RISØ National Laboratory, Roskilde,
Denmark Steven Bertman, Western Michigan
University, Kalamazoo, MI, USA Mary Anne Carroll,
University of Michigan, Ann Arbor, MI, USA Jan
Willem Erisman, Netherlands Energy Research
Foundation, Petten, The Netherlands David Fowler,
Centre for Ecology and Hydrology, Edinburgh
Research Station, Edinburgh, Scotland Alex
Guenther, National Center for Atmospheric
Research, Boulder, CO, USA Elisabeth Holland,
National Center for Atmospheric Research,
Boulder, CO, USA Luiz Martinelli, Universidade de
Sao Paulo, Sao Paul, Brazil Franz Meixner, Max
Planck Institute for Chemistry, Mainz,
Germany Knute Nadelhoffer, University of
Michigan, Ann Arbor, Michigan, USA Dominique
Serca, National Center for Scientific Research
(CNRS), Laboratoire d'Aérologie, Toulouse, France
Paul Shepson, Purdue University, West Lafayette,
Indiana, USA Jed Sparks, Cornell University,
Ithaca, New York, USA
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LEARN Proposed Steering Committee Claus Beier,
RISØ National Laboratory, Roskilde,
Denmark Steven Bertman, Western Michigan
University, Kalamazoo, MI, USA Mary Anne Carroll,
University of Michigan, Ann Arbor, MI, USA Jan
Willem Erisman, Netherlands Energy Research
Foundation, Petten, The Netherlands David Fowler,
Centre for Ecology and Hydrology, Edinburgh
Research Station, Edinburgh, Scotland Alex
Guenther, National Center for Atmospheric
Research, Boulder, CO, USA Elisabeth Holland,
National Center for Atmospheric Research,
Boulder, CO, USA Luiz Martinelli, Universidade de
Sao Paulo, Sao Paul, Brazil Franz Meixner, Max
Planck Institute for Chemistry, Mainz,
Germany Knute Nadelhoffer, University of
Michigan, Ann Arbor, Michigan, USA Dominique
Serca, National Center for Scientific Research
(CNRS), Laboratoire d'Aérologie, Toulouse, France
Paul Shepson, Purdue University, West Lafayette,
Indiana, USA Jed Sparks, Cornell University,
Ithaca, New York, USA
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Science Issues The critical questions involving
atmosphere-terrestrial biosphere exchange of
reactive nitrogen described below have been
identified by scientists with expertise in plant
physiological ecology, soil microbiology and
biochemistry, nutrient transfer and
biogeochemistry, atmospheric chemistry and
composition, biosphere/atmosphere fluxes, and
integrated modeling U.S. Nitrogen Science Plan,
2004. They concern

• Atmosphere-Biosphere Interactions
• Emissions
• Deposition and Foliar Uptake
• Canopy Assimilation and Ecosystem Response
• Atmospheric Chemistry and Atmosphere-Biosphere
  Feedbacks
• C. Other Important Interactions
  Ecosystem-community effects

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EMISSIONS
ATMOSPHERIC CHEMISTRY
ECOSYSTEM RESPONSE
REMOBILIZATION
ASSIMILATION
DEPOSITION
FOLIAR UPTAKE
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See proposal
Atmosphere-Biosphere Interactions
1. Emissions a) What is the spatial and
temporal variation in emission of the dominant
nitrogen trace gases (NO2, NO, N2O, and
NH3)? b) What is the influence of soil moisture
on partitioning of gaseous N emissions? How do
soil wetting/drying dynamics affect
emissions? c) What role do terrestrial ecosystem
emissions of particles, CO, oxygenated VOCs,
monoterpenes and sesquiterpenes have on
determining the atmospheric fate of nitrogen
compounds? d) How will emission patterns and
atmospheric chemical processing respond to
changes in climate, land use, and the chemical
composition of the atmosphere? e) How will
whole-ecosystem emissions respond to changes in
nitrogen inputs?
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See proposal
Atmosphere-Biosphere Interactions

• Deposition And Foliar Uptake
• What are the dominant receptor points for
  nitrogen (and other) gases across the landscape?
  How is nitrogen flux partitioned across receptor
  points?
• What are the physiological controls over and the
  relative importance of canopy uptake of nitrogen?
• What is the relative role of revolatilization,
  cuticular transfer, stomatal uptake and wash-off
  to the overall flux of nitrogen between the
  atmosphere and biosphere?
• What are the physical and biological controls on
  the compensation points for NO2 and NH3 (and
  other N gas species)?
• Is it legitimate to apply the micrometeorological
  techniques used for measuring fluxes of water
  vapor and CO2 to reactive gases or to
  non-homogeneous and complex surfaces such as
  forests?
• What is the cause of the large discrepancies
  observed between particle flux measurements and
  models?
• How do atmospheric flux components interact
  (i.e., how do co-deposition of gases and
  particles affect surface affinity and uptake)?

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See proposal
Atmosphere-Biosphere Interactions

• Canopy Assimilation and Ecosystem Response
• a) What are the mechanisms and magnitudes of
  secondary chemical reactions and processes
  occurring inside the leaf (i.e., mesophyll
  resistance) that define the assimilation rate of
  reactive nitrogen into the canopy?
• b) What is the partitioning and impact of canopy
  versus soil derived nitrogen sources? Are they
  fundamentally different in terms of ecosystem
  response?
• c) What is the carbon yield of nitrogen
  incorporation from differential incorporation
  pathways?
• d) What are the relative strengths of critical
  feedbacks between atmospheric and biospheric
  processes (e.g., nitrogen addition, elevated CO2,
  ozone formation)?

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Atmospheric Chemistry and Atmosphere-Biosphere
Feedbacks
See proposal
a) What oxidation products of NOx are formed
under different atmospheric conditions and how
are they partitioned? b) What are the mechanisms
of formation, reaction rates and product
properties of multifunctional organic nitrates?
What is their role and importance? c) What are
the deposition velocities for reactive nitrogen
compounds? d) What is the role of NO3 in daytime
photochemistry in forest environments? e) Is
nighttime chemistry involving biogenic emissions
of hydrocarbons and reactive nitrogen important
to the formation of organic nitrates? If so,
what are the biogenic species, the chemical
mechanisms and reaction rates, and the oxidation
products?
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Atmospheric Chemistry and Atmosphere-Biosphere
Feedbacks
See proposal
f) How does turbulent mixing within the nocturnal
boundary layer affect reactive nitrogen species
distributions? g) What is the role of
heterogeneous chemistry in the processing of
atmospheric reactive nitrogen and the formation
of oxidants? h) What controls the biogenic
emissions and the mechanisms of oxidation and
reaction rates of oxygenated and
higher-molecular-weight VOCs? What is their
role in the formation of organic nitrates? i) How
does mixing in complex canopies and uneven or
sloping terrain affect biogenic emissions and
the within-canopy chemical and physical
processes that determine partitioning of
gaseous and aerosol reactive nitrogen? With
what affect on above-canopy fluxes?
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Other Important Interactions Ecosystem-community
effects
See proposal

• What structures plant and microbial communities
  naturally? Can a baseline be generated to make
  comparisons to system experiencing increased N
  deposition?
• What are the key interactions when controls are
  altered simultaneously (i.e., concominant
  increase in nitrogen deposition and temperature)?
• How will local or regional perturbations be
  influenced by global-scale anthropogenic forcing
  factors? What are the interactions with other
  global change drivers?
• What are the controls of soil moisture content on
  fungal communities/function?
• e) How will plant-fungus associations (i.e.,
  mycorrhizae) be influenced by perturbations to
  the nitrogen cycle in native and managed systems?

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Measurement and Modeling Recommendations
See proposal

• Atmosphere-Biosphere Interactions Emissions
• Develop initial algorithms using enclosure
  emission measurement systems and test results
  of initial studies at existing manipulative field
  sites (e.g., elevated CO2, nutrient amendments,
  water, ozone, temperature).
• Make simultaneous nitrogen and carbon flux
  measurements at existing tower flux sites
  located in a few key ecosystems. Quantify
  temporal variations in emissions.
• Use aircraft flux measurements to evaluate the
  ability of emission models to extrapolate to
  regional scales and to characterize emission
  responses to land use and climate changes.

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Measurement and Modeling Recommendations
See proposal

• Atmosphere-Biosphere Interactions Deposition
  and Foliar Uptake
• Conduct detailed chamber experiments to quantify
  canopy assimilation of reactive nitrogen,
  synergistic effects, and non-linearities at
  realistic concentrations.
• Using a group of tower sites that reflect
  gradients in magnitude and speciation of
  nitrogen fluxes and pool sizes, climate and
  ecosystem type, conduct detailed ecosystem
  integrated measurements including the
  quantification of all major nitrogen and carbon
  fluxes along the atmosphere-biosphere-hydrosphere
  continuum.
• Develop modeling tools to scale detailed uptake
  models/experiments to regional/global scales.

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Measurement and Modeling Recommendations
See proposal

• Atmosphere-Biosphere Interactions Canopy
  Assimilation and Ecosystem Response
• Using experimental laboratory protocols, quantify
  the assimilation chemistry governing canopy
  assimilation of nitrogen into plant and/or
  microbial metabolism.
• Develop parameterized models based on
  fertilization experiments to estimate the carbon
  yield of nitrogen addition by differential
  pathways.
• Begin the development of holistic models
  considering nitrogen transformation and flux
  in both the atmospheric and biospheric
  compartment with emphasis on feedbacks,
  co-limitation, and commingled affects.

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Measurement and Modeling Recommendations
See proposal

• Atmospheric Chemistry and Atmosphere-Biosphere
  Feedbacks
• a) Conduct controlled laboratory studies of gas
  phase and heterogeneous reactions to determine
  reaction mechanisms for oxygenated and
  higher-molecular biogenic VOCs and identify and
  quantify VOC oxidation products under realistic
  conditions.
• b) Augment existing field programs that focus on
  limited aspects of nitrogen and carbon cycling to
  obtain comprehensive suites of observations
  including surface fluxes and concentration
  gradients of key reactants, intermediates, and
  products as well as the critical meteorology.
• c) Employ satellite observations to further test
  our understanding of NOx emissions and
  distributions.
• Further develop /evaluate analytical capabilities
  
• Couple atmospheric models to process-based
  vegetation models that predict uptake and
  emission of nitrogen species from a vertically
  resolved canopy driven by vegetation physiology.

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Measurement and Modeling Recommendations
See proposal
Atmospheric Chemistry and Atmosphere-Biosphere
Feedbacks f) Using 1-d models that include
detailed turbulent mixing, constrained by
observed micrometeorology and concentrations of
selected tracers, conduct studies of the details
of rapid chemical reactions and exchanges in the
canopy. g) Using 3-dimensional chemical tracer
models that have parameterized the sub grid
processes, conduct studies of the distribution of
longer-lived species and to make predictions at
larger horizontal scales.
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Measurement and Modeling Recommendations
See proposal

• Other Important Interactions and Connections
  Modeling and Integrated Database
  Development
• Foster the development and testing of integrated
  river-basin models for nitrogen export.
• Develop (or improve) process models of coupled
  water, carbon, and nitrogen transport and
  transformation that (to) include terrestrial
  components of the hydrologic cycle. Test models
  against data from integrated databases and
  results of field studies.
• Develop infrastructure and protocols for
  coherency in addressing issues of data quality,
  consistencies of methodologies and reporting and
  linkage of traditional hydrology and water
  quality data with other areas of information that
  inform on nitrogen cycling (e.g., fertilizer
  accounting data, drainage networks,
  land-atmosphere flux data, and nutrient cycling
  rate data).

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Measurement and Modeling Recommendations
See proposal

• Other Important Interactions and Connections
  Ecosystem-community effects
• Conduct empirical studies of plant and microbial
  community composition and spatial and temporal
  variability in response to nitrogen perturbation.
• Leverage current large-scale studies aimed at
  assessing carbon cycling (FACE and Ameriflux
  experiments) to include nitrogen treatments and
  explore plant and microbial community dynamics.
• Foster technologies (e.g., genetic
  fingerprinting, sequencing) to augment our
  understanding of microbial species identity and
  how it relates to biogeochemical function.
• Develop or utilize existing networks of long-term
  field sites (or databases) to track changes in
  plant and microbial community composition under
  altered nitrogen cycling regimes.

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Regional and Global Aspects
Implementation of the LEARN project within
iLEAPS will extend the work of several
international efforts that have worked to
synthesize information on human alteration of the
nitrogen cycle (e.g., the International SCOPE
Project on Nitrogen Transport and
Transformations) and will be conducted in
parallel with projects focusing on aquatic
ecosystems (e.g., the Comprehensive Federal
Interagency Research Plan). LEARN will focus on
the integration of research efforts focusing on
atmosphere-terrestrial biosphere exchange of
reactive nitrogen and on leveraging upon and
expanding existing networks currently focusing on
the terrestrial carbon cycle to include reactive
nitrogen measurements.
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Regional and Global Aspects, continued
In cooperation with the Global Land Project and
IGAC, LEARN will encourage and support the
integration of expertise in plant physiological
ecology, soil microbiology and biochemistry,
nutrient transfer and biogeochemistry,
atmospheric chemistry and composition,
biosphere/atmosphere fluxes, and integrated
modeling in the organization of multilateral,
interdisciplinary studies of reactive nitrogen
cycling and impacts. LEARN will also encourage
and support the extension of current focus sites
to include additional interdisciplinary
activities and the integration of ground-based
studies with aircraft and satellite observations.
LEARN will encourage the involvement of
scientists from developing countries by seeking
collaborations and making demographic inclusivity
at related conferences and summer schools a
priority. LEARN will also explore where best to
focus its observational studies through
conversations with the international community.
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iLEAPS/LEARN and AIMES/INI
The International Nitrogen Initiative (INI) has
transitioned from a Fast-Track project to a
regular project within IGBPs integrative
activity focusing on Analysis, Integration and
Modeling of the Earth System (AIMES). INIs
goal is to optimize nitrogens beneficial role
in sustainable food production and minimize
nitrogens negative effects on human health and
the environment resulting from food and energy
production. INI, under AMES, is responsible
for the international integration of nitrogen
acitivites and is focusing on scientific
assessment, development of solutions to solve a
wide variety of problems, and interactions with
policymakers to implement these solutions.
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Relationship between LEARN and INI
LEARN, under iLEAPS, would be one of several IGBP
projects that will conduct research and other
activities that will be useful to INI in its
assessment role.
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LEARN Proposed Steering Committee Claus Beier,
RISØ National Laboratory, Roskilde,
Denmark Steven Bertman, Western Michigan
University, Kalamazoo, MI, USA Mary Anne Carroll,
University of Michigan, Ann Arbor, MI, USA Jan
Willem Erisman, Netherlands Energy Research
Foundation, Petten, The Netherlands David Fowler,
Centre for Ecology and Hydrology, Edinburgh
Research Station, Edinburgh, Scotland Alex
Guenther, National Center for Atmospheric
Research, Boulder, CO, USA Elisabeth Holland,
National Center for Atmospheric Research,
Boulder, CO, USA Luiz Martinelli, Universidade
de Sao Paulo, Sao Paul, Brazil Franz Meixner, Max
Planck Institute for Chemistry, Mainz,
Germany Knute Nadelhoffer, University of
Michigan, Ann Arbor, Michigan, USA Dominique
Serca, National Center for Scientific Research
(CNRS), Laboratoire d'Aérologie, Toulouse, France
Paul Shepson, Purdue University, West Lafayette,
Indiana, USA Jed Sparks, Cornell University,
Ithaca, New York, USA INI Regional Center
Director or Oversight Committee Member
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Capacity Building and Knowledge Transfer
LEARN will foster exchange between and
integration of traditionally more narrowly
oriented disciplines, including plant
physiological ecology, soil microbiology,
meteorology, and atmospheric chemistry. This
will be done via workshops focusing on
crossdisciplinary experimental design and through
on-site summer schools. LEARN will assist
iLEAPS in exploring knowledge transfer and junior
scientist career support though such vehicles as
student exchange and postdoctoral fellowships and
mid-career support through such vehicles as
exchanges and/or sabbaticals.
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This is a list of potential participants only. .
Although many of the potential participants
have been in contact with the organizers in
relation to ongoing science planning and research
activities, many of the potential participants on
this list have not yet been contacted regarding
this activity. They are listed to indicate the
potential breadth and depth of the proposed
activity.
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Issues
LEARN Proposed Steering Committee Add
participants from Africa and Asia Invite
someone from DEBITS SSC?
LEARN is expected to be a multi-year project,
with integrated planning and experimental design
being the focus of years 1-2, and regional-based
focus studies conducted in an integrated fashion
(interdisciplinary modeling and measurement
activities) with the shorter- and longer-term
goals of facilitating global model development
and tests and assessment activities (years 3 5)
and obtaining a full understanding of
atmosphere-land ecosystem reactive nitrogen
exchange on a global basis (years 5 ).
Strategies for moving forward to productive
activities SC meeting to define initial tasks
and timeline Considering the formation of
working groups (e.g., joing iLEAPS/LEARN and GLP)
to address specific science questions / specific
regional activities
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North American Nitrogen Center
The North American Nitrogen Center is one of five
continental-scale centers of the International
Nitrogen Initiative sponsored by the
International Council of Science (ICSU) through
the Scientific Committee on Problems of the
Environment (SCOPE) and the International
Geosphere-Biosphere Program (IGBP).

• The goals of the North American Nitrogen Center
  are
• To better assess the sources of N pollution and
  the drivers of change in N cycling across the
  regions of North America, with an emphasis on
  evaluating trends in fluxes and environmental
  exposure.
• To comprehensively and quantitatively assess
  both the ecological and human-health consequences
  of N pollution in North America.
• Use existing coastal N assessments (extending to
  Canada and Mexico), emphasize other ecological
  effects and human health consequences
• To develop policy options for reducing N
  pollution and to encourage large-scale pilot
  studies to test potential policies and technical
  solutions.
• To communicate the issues of human acceleration
  of the N cycle to the public and to decision
  makers, and to facilitate communication and
  interaction among the scientific community.