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See detailORCHIDEE-CROP (v0), a new process based Agro-Land Surface Model: model description and evaluation over Europe
Wu, Xiuchen; Vuichard, N.; Ciais, P. et al

in Geoscientific Model Development Discussions [=GMDD] (2016), 8

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See detailInterpreting canopy development and physiology using a European phenology camera network at flux sites
Wingate, L.; Ogée, J.; Cremonese, E. et al

in Biogeosciences (2015), 12(10), 5995-6015

Plant phenological development is orchestrated through subtle changes in photoperiod, temperature, soil moisture and nutrient availability. Presently, the exact timing of plant development stages and ... [more ▼]

Plant phenological development is orchestrated through subtle changes in photoperiod, temperature, soil moisture and nutrient availability. Presently, the exact timing of plant development stages and their response to climate and management practices are crudely represented in land surface models. As visual observations of phenology are laborious, there is a need to supplement long-term observations with automated techniques such as those provided by digital repeat photography at high temporal and spatial resolution. We present the first synthesis from a growing observational network of digital cameras installed on towers across Europe above deciduous and evergreen forests, grasslands and croplands, where vegetation and atmosphere CO2 fluxes are measured continuously. Using colour indices from digital images and using piecewise regression analysis of time series, we explored whether key changes in canopy phenology could be detected automatically across different land use types in the network. The piecewise regression approach could capture the start and end of the growing season, in addition to identifying striking changes in colour signals caused by flowering and management practices such as mowing. Exploring the dates of green-up and senescence of deciduous forests extracted by the piecewise regression approach against dates estimated from visual observations, we found that these phenological events could be detected adequately (RMSE < 8 and 11 days for leaf out and leaf fall, respectively). We also investigated whether the seasonal patterns of red, green and blue colour fractions derived from digital images could be modelled mechanistically using the PROSAIL model parameterised with information of seasonal changes in canopy leaf area and leaf chlorophyll and carotenoid concentrations. From a model sensitivity analysis we found that variations in colour fractions, and in particular the late spring `green hump' observed repeatedly in deciduous broadleaf canopies across the network, are essentially dominated by changes in the respective pigment concentrations. Using the model we were able to explain why this spring maximum in green signal is often observed out of phase with the maximum period of canopy photosynthesis in ecosystems across Europe. Coupling such quasi-continuous digital records of canopy colours with co-located CO2 flux measurements will improve our understanding of how changes in growing season length are likely to shape the capacity of European ecosystems to sequester CO2 in the future. [less ▲]

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See detailContrasting response of European forest and grassland energy exchange to heatwaves
Teuling, A. J.; Seneviratne, S. I.; Stöckli, R. et al

in Nature Geoscience (2010), 3(10), 722-727

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See detailManagement effects on European cropland respiration
Eugster, W.; Moffat, A. M.; Ceschia, E. et al

in Agriculture, Ecosystems & Environment (2010), 139

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See detailManagement effects on net ecosystem carbon and GHG budgets at European crop sites
Ceschia, E.; Beziat, P.; Dejoux, J. F. et al

in Agriculture, Ecosystems & Environment (2010), 139

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See detailThe net biome production of full crop rotations in Europe
Kutsch, W. L.; Aubinet, Marc ULg; Buchmann, N. et al

in Agriculture, Ecosystems & Environment (2010), 139

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See detailExceptional Carbon Uptake In European Forests During The Warm Spring Of 2007: A Data-Model Analysis
Delpierre, N.; Soudani, K.; Kostner, B. et al

in Global Change Biology (2009), 15(6), 1455-1474

Temperate and boreal forests undergo drastic functional changes in the springtime, shifting within a few weeks from net carbon (C) sources to net C sinks. Most of these changes are mediated by temperature ... [more ▼]

Temperate and boreal forests undergo drastic functional changes in the springtime, shifting within a few weeks from net carbon (C) sources to net C sinks. Most of these changes are mediated by temperature. The autumn 2006-winter 2007 record warm period was followed by an exceptionally warm spring in Europe, making spring 2007 a good candidate for advances in the onset of the photosynthetically active period. An analysis of a decade of eddy covariance data from six European forests stands, which encompass a wide range of functional types (broadleaf evergreen, broadleaf deciduous, needleleaf evergreen) and a wide latitudinal band (from 44 degrees to 62 degrees N), revealed exceptional fluxes during spring 2007. Gross primary productivity (GPP) of spring 2007 was the maximum recorded in the decade examined for all sites but a Mediterranean evergreen forest (with a +40 to +130 gC m(-2) anomaly compared with the decadal mean over the January-May period). Total ecosystem respiration (TER) was also promoted during spring 2007, though less anomalous than GPP (with a +17 to +93 gC m(-2) anomaly over 5 months), leading to higher net uptake than the long-term mean at all sites (+12 to +79 gC m(-2) anomaly over 5 months). A correlative analysis relating springtime C fluxes to simple phenological indices suggested spring C uptake and temperatures to be related. The CASTANEA process-based model was used to disentangle the seasonality of climatic drivers (incoming radiation, air and soil temperatures) and biological drivers (canopy dynamics, thermal acclimation of photosynthesis to low temperatures) on spring C fluxes along the latitudinal gradient. A sensitivity analysis of model simulations evidenced the roles of (i) an exceptional early budburst combined with elevated air temperature in deciduous sites, and (ii) an early relief of winter thermal acclimation in coniferous sites for the promotion of 2007 spring assimilation. [less ▲]

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See detailEvidence For Soil Water Control On Carbon And Water Dynamics In European Forests During The Extremely Dry Year: 2003
Granier, A.; Reichstein, M.; Breda, N. et al

in Agricultural and Forest Meteorology (2007), 143(1-2),

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See detailReduction Of Ecosystem Productivity And Respiration During The European Summer 2003 Climate Anomaly: A Joint Flux Tower, Remote Sensing And Modelling Analysis
Reichstein, M.; Ciais, P.; Papale, D. et al

in Global Change Biology (2007), 13(3),

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See detailAn Analysis of Soil Respiration across Northern Hemisphere Temperate Ecosystems
Hibbard, K. A.; Law, B. E.; Reichstein, M. et al

in Biogeochemistry (2005), 73(1), 29-70

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See detailQuality Analysis Applied On Eddy Covariance Measurements At Complex Forest Sites Using Footprint Modelling
Rebmann, C.; Gockede, M.; Foken, T. et al

in Theoretical and Applied Climatology (2005), 80(2-4),

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See detailEurope-Wide Reduction In Primary Productivity Caused By The Heat And Drought In 2003
Ciais, P.; Reichstein, M.; Viovy, N. et al

in Nature (2005), 437(7058),

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See detailSpruce forests (Norway and Sitka spruce, including Douglas fir): Carbon and water fluxes, Balances, Ecological and ecophysiological determinants
Bernhofer, C.; Aubinet, Marc ULg; Clément, R. et al

in Valentini, Riccardo (Ed.) Fluxes of Carbon, Water and Energy of European Forests (2003)

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See detailCarbon balance gradient in European forests: should we doubt 'surprising' results? A reply to Piovesan & Adams
Jarvis, P. G.; Dolman, A. J.; Schulze, E. D. et al

in Journal of Vegetation Science (2001), 12(1), 145-150

This paper responds to the Forum contribution by Piovesan & Adams (2000) who criticized the results obtained by the EUROFLUX network on carbon fluxes of several European forests. The major point of ... [more ▼]

This paper responds to the Forum contribution by Piovesan & Adams (2000) who criticized the results obtained by the EUROFLUX network on carbon fluxes of several European forests. The major point of criticism was that the data provided by EUROFLUX are inconsistent with current scientific understanding. It is argued that understanding the terrestrial global carbon cycle requires more than simply restating what was known previously, and that Piovesan & Adams have not been able to show any major conflicts between our findings and ecosystem or atmospheric-transport theories. [less ▲]

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See detailGap Filling Strategies For Long Term Energy Flux Data Sets
Falge, E.; Baldocchi, D.; Olson, R. et al

in Agricultural and Forest Meteorology (2001), 107(1),

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See detailGap Filling Strategies For Defensible Annual Sums Of Net Ecosystem Exchange
Falge, E.; Baldocchi, D.; Olson, R. et al

in Agricultural and Forest Meteorology (2001), 107(1),

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See detailProductivity Overshadows Temperature In Determining Soil And Ecosystem Respiration Across European Forests
Janssens, Ia.; Lankreijer, H.; Matteucci, G. et al

in Global Change Biology (2001), 7(3),

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See detailRespiration As The Main Determinant Of Carbon Balance In European Forests
Valentini, R.; Matteucci, G.; Dolman, Aj. et al

in Nature (2000), 404(6780),

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See detailEstimates of the annual net carbon and water exchange of forests: the EUROFLUX methodology.
Aubinet, Marc ULg; Grelle, A.; Ibrom, A. et al

in Advances in Ecological Research (1999), 30

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