Training in multi-scale approaches to understanding carbon dynamics in Arctic and upland systems

A network of Marie Curie host fellowships for Early Stage Research Training

MULTIARC fellowships

Leaf, Plant and Vegetation gas exchange

1 Fellow @ University of Sheffield, UK
Lead supervisors: Professor Malcolm C Press & Dr Gareth K Phoenix

Position filled: Eva Koller

Key aims are to determine the inherent capacities of key vegetation types along the carbon storage gradient (glacial chronosequence) to sequester carbon by assessment of both leaf and whole plant level measurements of gas exchange. The project will aim to understand how this carbon sequestration is driven by the traits of component plants (photosynthesis, respiration, growth rates, seasonal and longer-term dynamics), the availability of nutrients within the system. Existing field manipulation experiments will also allow opportunity to determine the sensitivity of plant functional types to environmental change and how this will impact on plant scale carbon dynamics.

1 Fellow @ Abisko Scientific Research Station (ANS), Sweden
Lead supervisor: Professor Torben Christensen

Position filled: Michal Heliasz

This project aims to determine the role of vegetation in larger scale carbon dynamics. To scale up, measurements of carbon fluxes will be made at the plot and larger scale through the use of field chambers and via eddy-flux-covariance towers. Spatial and temporal variability of landscape scale fluxes based on multiple eddy co-variance tower measurements will be analysed. These data will allow the fellow to ascertain the extent to which photosynthesis and respiration at the level of the species/functional type drive community gas exchange. Critical factors determining the annual C-balance at the landscape scale will be identified and used as validation for the behaviour of larger scale model based C flux estimates.

Plant/decomposition/soil interactions

2 Fellows @ VU Amsterdam, The Netherlands
Lead supervisors: Professor Rien Aerts & Dr Hans Cornelissen

Positions Filled: Gregoire Freschet and Marika Makkonen

Following fixation (acquisition) of carbon by plants, decomposition of litter is a limiting step that controls the subsequent cycling of carbon (and nutrients) in upland and Arctic systems. Decomposition is particularly important in these communities since low tissue quality and climatic constraints limit decomposition rates resulting in large accumulation of organic matter with knock-on feedback to the global carbon balance and climate. Here, important issues of scaling prevail since the key drivers of litter production and decomposition rates (e.g. topography, soil hydrology, temperatures, quality of the litter produced) operate at different scales.
These fellowships will combine five research avenues to quantify and interpret litter decomposition at plot, ecosystem and catchment scales. (1) Simultaneous screening of root, rhizome and stem decomposition of dominant species from key ecosystems. (2) In situ litter decomposition and soil respiration studies in different ecosystems for representative dominant species. (3) Quantifying litter inputs in key ecosystems such that fluxes determined above (at the plot level) can be scaled to the ecosystem and catchment. (4) Effects of climate warming and hydrological change on decomposition rates and carbon fluxes using existing long-term in situ climate manipulation experiments (Abisko only), applying experimental 13C labelling.

Soil leachate carbon dynamics and catchment hydrochemistry

1 Fellow @ University of Sheffield, UK
Lead Supervisors: Dr Andy Hodson and Dr Gareth Phoenix

Position filled: Nils Ohlanders

This fellowship will integrate the plant orientated fellowships and provide a bridge to scaling from plant-scale carbon dynamics to the stream, river, lake and catchment carbon dynamics. To achieve this, detailed monitoring will be taken of soil water chemistry, carbon loads and nutrients, within the major vegetation types of the contrasting catchments. These data will be linked to the vegetation monitoring, soil respiration and decomposition studies (detailed on this page) to gain a fuller understanding of the biotic controls on leachate carbon fluxes and chemistry. The resulting detailed data sets and monitoring of leachate volumes will be used to determine system efflux of carbon to water systems.

This will be coupled with freshwater monitoring of major ions and the various organic/inorganic fractions of carbon, nitrogen and phosphorus will be collected from the river systems throughout the annual water cycle. Differences in the composition and fluxes of these constituents at key nodes within the river systems will characterise the nature and locus of important processes governing the sequestration and downstream fate of dissolved carbon. Particular attention will be given to biogeochemical controls upon inorganic carbon sequestration from mineral weathering, to organic carbon inputs and their changes along the stream network and to CO2 and CH4 gas transfers across the air/water interface.

Integrating across scales

1 Fellow @ Abisko Scientific Research Station (ANS), Sweden
Lead supervisor: Professor Terry Callaghan & Dr Ed Hanna

Position filled: Yang Zhenlin

This fellow will simulate historic (ca. 1900 to present) climatic variability and change across the catchment using meteorological station measurements, European Centre for Medium Range for Weather Forecasts (ECMWF) meteorological reanalysis and a digital elevation model, to relate micrometeorologial variations across the catchment to the wider synoptic scale. This will involve improved calculations of lapse rates, snow/ice melting and shading, using a combination of empirical and modelled data and tools such as the Solar Analyst (Helios Environmental Modeling Institute, LLC). We will then apply our knowledge of surface air temperature and precipitation variations across the catchment to GCM scenarios of future regional climatic change. Past and future climate thus simulated will form the basis of temperature, precipitation (including snowfall) and radiation series which will be used to drive models of carbon cycling and plant/ecosystem processes.

Data from other fellowships will be used to model carbon storage, accumulation and release within the model catchments. Models will be developed and/or applied which describe how small-scale, upstream processes (e.g. plant type and traits, soil, nutrients, topography, hydrology) impact on catchment scale C dynamics (including testing against empirical data). Additionally, scenarios of climate impacts on different components of catchment C dynamics can be explored (using in part, the empirical data from other fellows) to predict environmental change impacts on those catchment C dynamics. The approach will utilize Dynamic Global Vegetation models (DGVMs) and will build on the modelling of ecosystem structure and function in the context of future climate scenarios and downscaling of climate to the plot level.

Updated February 2008