An Integrated Network for Terrestrial Ecosystem Research on Feedbacks to the Atmosphere and ClimatE (INTERFACE): Linking experimentalists, ecosystem modelers, and Earth system modelers
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Keflavik group

CLIMMANI/INTERFACE joint workshop:

Nutrient constraints on the net carbon balance

June 15-17, 2011
Keflavik, Iceland

The INTERFACE and CLIMMANI networks bring together researchers working on climate change effects in terrestrial ecosystems in order to facilitate interaction, syntheses of results and collaboration. In particular, bringing experimentalists and ecosystem and Earth system modelers together has a special priority.

This workshop explored 6 topics that we believe are keys to understanding how the net carbon balance is controlled by nutrient interactions. Each session synthesized and discussed the state of knowledge within one of these areas and identified gaps in knowledge and abilities to model it at a local and global scale. Each session lasted 2½ hours. The overarching goal of the workshop was to catalyze discussions and future activities that improve the realism of Earth system models.

Local organizers were Bjarni D. Sigurdsson and Helena M. Stefansdottir from the Agricultural University of Iceland.

Scientific organizing committee  

Claus Beier

Bridget Emmett

Jeff Dukes

Peter Thornton

Session Topic Question Session Chairs
Session 1
Wed. 15th June
Carbon availability as a control on carbon sequestration To what extent is carbon uptake in plants controlled by CO2 availability or by plant demand – is atmospheric CO2 concentration or the carbon consumption by growth driving sequestration, and is this correctly described in plot scale and Earth system models?

Christian Körner

Steve Running

Hendrik Poorter: Is plant growth driven by photosynthesis?

Christian Körner: Concepts and constraints for scaling from baseline metabolism to ecosystem carbon relations

Reto Stockli: Integrating the terrestrial water and carbon cycles in Earth Systems

Steve Running: Global scale calculations of the terrestrial carbon and water cycle components with remote sensing.

Session 2
Wed. 15th June
Nitrogen limitation and nitrogen fixation Nitrogen is one of the prime limiting factors for carbon sequestration. Consequently, the input of N to a given site is important for understanding future responses of carbon sequestration. One of the main unknown input fluxes is nitrogen fixation, which is associated with both methodological problems as well as lack of process understanding.

Tom DeLuca

Elena Shevliakova

Dr. Stefan Gerber: Global dynamic land modelling of C & N cycling.

Dr. Lianhai Wu: Ecosystem scale modelling of C and N flux incorporating leguminous N fixation in agricultural systems.

Dr. Sasha Reed: Topic area: Controls on N fixation in tropical ecosystems.

Michael Gundale: Nitrogen fixation in moss communities in boreal forests and broader influence on ecosystem N cycle.
Session 3
Wed. 15th June
Phosphorus limitations to plant growth and microbial processes Nitrogen receives attention as a primary constraint on carbon sequestration in terrestrial ecosystems. However, it is generally accepted that phosphorus may play an increasing role in many ecosystems.  This needs to be experimentally investigated and documented, as P cycling may need to be included in modeling frameworks.

Cory Cleveland

Lina Mercado

Jon Lloyd:  Phosphorus and tropical ecosystem productivity: A critical evaluation of the Vitousek Paradigm 25+ years on  

Ben Turner:  Nutrient limitation of above and below-ground productivity in lowland and montane tropical rain forest

Ben Houlton:  A framework for representing P in earth system models

Lina Mercado:  Accounting for  N &P limitations in tropical forests using the land component of an earth system model

Session 4
Thurs. 16th June
Acidity and base cation availability as a controlling factor on soil carbon sequestration Recent findings indicate that soil acidity may strongly influence soil carbon sequestration and decomposition processes. This also has strong interactions with base cation status and macronutrient availability. How well do we understand these processes and are they included in our present models?

Filip Oulehle

Christy Goodale

Filip Ouhle: Major changes in forest carbon and nitrogen cycling caused by declining sulphur deposition.

Frank Berninger: Long term changes in tree productivity as a response to acid and nitrogenous deposition, evidence from tree rings and isotopes.

Vince Gauci: Sulfur deposition and methane emissions from wetland soils

April Melvin: Calcium fertilization alters forest carbon storage

Session 5
Thurs. 16th June
Ecological adaptation and its impacts, interactions and controls on resource availability Resource availability and limitations may have a direct impact on carbon sequestration processes, but also affect ecological processes and plant species composition, which feed back to resource availability. How well do we understand these processes and their indirect control on resource availability, and can we model them?

Sarah Hobbie

Ben Smith

Rüdiger Grote: Resource-use description in physiologically-based models – A major restriction for describing competition?

Will Cornwel: Limits to positive feedbacks: a more complete model for community assembly and species' effects on decomposition.

Katie Suding: Indirect controls on resource availability: a trait-based effect and response framework to understand when community change matters.

Rosie Fisher: The representation of space and stochasticity in one-dimensional and deterministic global vegetation models
Session 6
Thurs. 16th June
Nitrogen limitation as a controlling factor for soil carbon dynamics Nitrogen is often considered to be the prime and general limiting factor for carbon sequestration in terrestrial ecosystems. There is increasing debate on the role of N in controlling soil carbon dynamics.

Ivan Janssens

Marc Post

Ivan Janssens: N deposition and fertilization reduce soil respiration: Evidence and mechanisms.

Peter van Bodegom: Towards global quantification of soil N-C-cycles by coupling trait-based vegetation models to microbial biomass induced soil mineralization models

Marc Post: Representations soil carbon dynamics and nitrogen limitation of decomposition in terrestrial ecosystem models: Present and future directions

Pam Templer: Impact of nitrogen deposition on carbon storage in terrestrial ecosystems

Poster Session
Thurs. 16th June
Claus Beier
Jeff Dukes


Thurs. 16th June
Jeff Dukes
Claus Beier

  13th June 14th June 15th June 16th June 17th June
9.00-11.30   Iceland Excursion Session 1 Session 4 General discussion and wrap up
13.00-15.30   Iceland Excursion Session 2 Session 5 Lunch and/or departure
16.00-18.30 Arrival for some

Arrival for some Iceland Excursion

Session 3 Session 6  
    Dinner and icebreaker Conference dinner Poster session and snack - dinner  
Purdue University | Biological Sciences.