Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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Atmospheric deposition, CO2, and change in the land carbon sink
Fernández-Martínez, M. ; Vicca, S. ; Janssens, I.A. ; Ciais, P. ; Obersteiner, M. ; Bartrons, M. ; Sardans, Jordi ; Verger, Aleixandre ; Canadell, J.G. ; Chevallier, F. ; Wang, X. ; Bernhofer, C. ; Curtis, P.S. ; Gianelle, D. ; Grünwald, T. ; Heinesch, B. ; Ibrom, A. ; Knohl, A. ; Laurila, T. ; Law, Beverly E. ; Limousin, J.M. ; Longdoz, B. ; Loustau, D. ; Mammarella, I. ; Matteucci, G. ; Monson, R.K. ; Montagnani, L. ; Moors, E.J. ; Munger, J.W. ; Papale, D. ; Piao, S.L. ; Peñuelas, J. - \ 2017
Scientific Reports 7 (2017). - ISSN 2045-2322 - 13 p.

Concentrations of atmospheric carbon dioxide (CO2) have continued to increase whereas atmospheric deposition of sulphur and nitrogen has declined in Europe and the USA during recent decades. Using time series of flux observations from 23 forests distributed throughout Europe and the USA, and generalised mixed models, we found that forest-level net ecosystem production and gross primary production have increased by 1% annually from 1995 to 2011. Statistical models indicated that increasing atmospheric CO2 was the most important factor driving the increasing strength of carbon sinks in these forests. We also found that the reduction of sulphur deposition in Europe and the USA lead to higher recovery in ecosystem respiration than in gross primary production, thus limiting the increase of carbon sequestration. By contrast, trends in climate and nitrogen deposition did not significantly contribute to changing carbon fluxes during the studied period. Our findings support the hypothesis of a general CO2-fertilization effect on vegetation growth and suggest that, so far unknown, sulphur deposition plays a significant role in the carbon balance of forests in industrialized regions. Our results show the need to include the effects of changing atmospheric composition, beyond CO2, to assess future dynamics of carbon-climate feedbacks not currently considered in earth system/climate modelling.

Thermal adaptation of net ecosystem exchange
Yuan, W. ; Luo, Y. ; Liang, S. ; YU, G. ; Niu, S. ; Stoy, J. ; Chen, J. ; Desai, A.R. ; Lindroth, A. ; Gough, C.M. ; Ceulenmans, R. ; Arain, A. ; Bernhofer, C. ; Cook, B. ; Cook, D.R. ; Dragoni, D. ; Gielen, B. ; Janssens, I.A. ; Longdoz, B. ; Liu, H. ; Lund, M. ; Matteucci, G. ; Moors, E.J. ; Scott, R.L. ; Seufert, G. ; Varner, R. - \ 2011
Biogeosciences 8 (2011)6. - ISSN 1726-4170 - p. 1453 - 1463.
carbon-dioxide exchange - long-term measurements - oak-dominated forest - scots pine forest - sub-alpine forest - soil respiration - deciduous forest - interannual variability - temperate forest - european forests
Thermal adaptation of gross primary production and ecosystem respiration has been well documented over broad thermal gradients. However, no study has examined their interaction as a function of temperature, i.e. the thermal responses of net ecosystem exchange of carbon (NEE). In this study, we constructed temperature response curves of NEE against temperature using 380 site-years of eddy covariance data at 72 forest, grassland and shrubland ecosystems located at latitudes ranging from ~29° N to 64° N. The response curves were used to define two critical temperatures: transition temperature (Tb) at which ecosystem transfer from carbon source to sink and optimal temperature (To) at which carbon uptake is maximized. Tb was strongly correlated with annual mean air temperature. To was strongly correlated with mean temperature during the net carbon uptake period across the study ecosystems. Our results imply that the net ecosystem exchange of carbon adapts to the temperature across the geographical range due to intrinsic connections between vegetation primary production and ecosystem respiration.
Impact of severe dry season on net ecosystem exchange in the Neotropical rainforest of French Guiana
Bonal, D. ; Bosc, A. ; Ponton, S. ; Goret, J. ; Burban, B. ; Gross, P. ; Bonnefonds, J.M. ; Elbers, J.A. ; Longdoz, B. ; Epron, D. ; Guehl, J. ; Granier, A. - \ 2008
Global Change Biology 14 (2008)8. - ISSN 1354-1013 - p. 1917 - 1933.
ecosystemen - droog seizoen - tropische regenbossen - eddy-covariantie - netto ecosysteem koolstofbalans - atmosferische grenslaag - droogte - frans-guyana - ecosystems - dry season - tropical rain forests - eddy covariance - net ecosystem carbon balance - atmospheric boundary-layer - drought - french guiana - transitional tropical forest - carbon-dioxide uptake - soil co2 efflux - european forests - amazonian ecosystems - respiration - climate - fluxes
The lack of information on the ways seasonal drought modifies the CO2 exchange between Neotropical rainforest ecosystems and the atmosphere and the resulting carbon balance hinders our ability to precisely predict how these ecosystems will respond as global environmental changes force them to face increasingly contrasting conditions in the future. To address this issue, seasonal variations in daily net ecosystem productivity (NEPd) and two main components of this productivity, daily total ecosystem respiration (REd) and daily gross ecosystem productivity (GEPd), were estimated over 2 years at a flux tower site in French Guiana, South America (5 °16'54"N, 52 °54'44"W). We compared seasonal variations between wet and dry periods and between dry periods of contrasting levels of intensity (i.e. mild vs. severe) during equivalent 93-day periods. During the wet periods, the ecosystem was almost in balance with the atmosphere (storage of 9.0 g C m¿2). Seasonal dry periods, regardless of their severity, are associated with higher incident radiation and lower REd combined with reduced soil respiration associated with low soil water availability. During the mild dry period, as is normally the case in this region, the amount of carbon stored in the ecosystem was 32.7 g C m¿2. Severe drought conditions resulted in even lower REd, whereas the photosynthetic activity was only moderately reduced and no change in canopy structure was observed. Thus, the severe dry period was characterized by greater carbon storage (64.6 g C m¿2), emphasizing that environmental conditions, such as during a severe drought, modify the CO2 exchange between Neotropical rainforest ecosystems and the atmosphere and potentially the resulting carbon balance
Quality control of CarboEurope flux data - Part 1: Coupling footprint analyses with flux data quality assessment to evaluate sites in forest ecosystems
Gockede, M. ; Foken, T. ; Aubinet, M. ; Aurela, M. ; Banza, J. ; Bernhofer, C. ; Bonnefonds, J.M. ; Brunet, Y. ; Carrara, A. ; Clement, R. ; Dellwik, E. ; Elbers, J.A. ; Eugster, W. ; Fuhrer, J. ; Granier, A. ; Grunwald, T. ; Heinsch, B. ; Janssens, I.A. ; Knohl, A. ; Koeble, R. ; Laurila, T. ; Longdoz, B. ; Manca, G. ; Marek, M. ; Markkanen, T. ; Mateus, J. ; Matteucci, G. ; Mauder, M. ; Migliavacca, M. ; Minerbi, S. ; Moncrieff, J. ; Montagnani, L. ; Moors, E.J. ; Ourcival, J.M. ; Papale, D. ; Pereira, J.M. ; Pilegaard, K. ; Pita, G. ; Rambal, S. ; Rebmann, C. ; Rodrigues, A. ; Rotenberg, E. ; Sanz, M.J. ; Sedlak, P. ; Seufert, G. ; Siebicke, L. ; Soussana, J.F. ; Valentini, R. ; Vesala, T. ; Verbeeck, H. ; Yakir, D. - \ 2008
Biogeosciences 5 (2008)2. - ISSN 1726-4170 - p. 433 - 450.
warmtestroming - eddy-covariantie - gegevensanalyse - ecosystemen - bossen - atmosferische grenslaag - heat flow - eddy covariance - data analysis - ecosystems - forests - atmospheric boundary-layer - eddy covariance measurements - water-vapor - boundary-layer - heat-flux - turbulence statistics - correlation systems - stochastic-models - sonic anemometer - surface fluxes - carbon-dioxide
We applied a site evaluation approach combining Lagrangian Stochastic footprint modeling with a quality assessment approach for eddy-covariance data to 25 forested sites of the CarboEurope-IP network. The analysis addresses the spatial representativeness of the flux measurements, instrumental effects on data quality, spatial patterns in the data quality, and the performance of the coordinate rotation method. Our findings demonstrate that application of a footprint filter could strengthen the CarboEurope-IP flux database, since only one third of the sites is situated in truly homogeneous terrain. Almost half of the sites experience a significant reduction in eddy-covariance data quality under certain conditions, though these effects are mostly constricted to a small portion of the dataset. Reductions in data quality of the sensible heat flux are mostly induced by characteristics of the surrounding terrain, while the latent heat flux is subject to instrumentation-related problems. The Planar-Fit coordinate rotation proved to be a reliable tool for the majority of the sites using only a single set of rotation angles. Overall, we found a high average data quality for the CarboEurope-IP network, with good representativeness of the measurement data for the specified target land cover types.
Evidence for soil water control on carbon and water dynamics in European forests during the extremely dry year: 2003
Granier, A. ; Reichstein, M. ; Bréda, N. ; Janssens, I.A. ; Falge, E. ; Ciais, P. ; Grünwald, T. ; Aubinet, M. ; Berbigier, P. ; Bernhofer, C. ; Buchmann, N. ; Facini, O. ; Grassi, G. ; Heinesch, B. ; Ilvesniemi, H. ; Keronen, P. ; Knohl, A. ; Köstner, B. ; Lagergren, F. ; Lindroth, A. ; Longdoz, B. ; Loustau, D. ; Mateus, J. ; Montagnani, L. ; Nys, C. ; Moors, E.J. ; Papale, D. ; Peiffer, M. ; Pilegaard, K. ; Pita, G. ; Pumpanen, J. ; Rambal, S. ; Rebmann, C. ; Rodrigues, A. ; Seufert, G. ; Tenhunen, J. ; Vesala, T. ; Wang, Q. - \ 2007
Agricultural and Forest Meteorology 143 (2007)1-2. - ISSN 0168-1923 - p. 123 - 145.
droogte - waterbalans - bodemwater - bossen - netto ecosysteem koolstofbalans - west-europa - drought - water balance - soil water - forests - net ecosystem carbon balance - western europe - leaf-area index - fagus-sylvatica l. - ecosystem co2 exchange - sap flow measurements - boreal aspen forest - canopy conductance - deciduous forest - severe drought - beech forest - scots pine
The drought of 2003 was exceptionally severe in many regions of Europe, both in duration and in intensity. In some areas, especially in Germany and France, it was the strongest drought for the last 50 years, lasting for more than 6 months. We used continuous carbon and water flux measurements at 12 European monitoring sites covering various forest ecosystem types and a large climatic range in order to characterise the consequences of this drought on ecosystems functioning. As soil water content in the root zone was only monitored in a few sites, a daily water balance model was implemented at each stand to estimate the water balance terms: trees and understorey transpiration, rainfall interception, throughfall, drainage in the different soil layers and soil water content. This model calculated the onset date, duration and intensity of the soil water shortage (called water stress) using measured climate and site properties: leaf area index and phenology that both determine tree transpiration and rainfall interception, soil characteristics and root distribution, both influencing water absorption and drainage. At sites where soil water content was measured, we observed a good agreement between measured and modelled soil water content. Our analysis showed a wide spatial distribution of drought stress over Europe, with a maximum intensity within a large band extending from Portugal to NE Germany. Vapour fluxes in all the investigated sites were reduced by drought, due to stomatal closure, when the relative extractable water in soil (REW) dropped below ca. 0.4. Rainfall events during the drought, however, typically induced rapid restoration of vapour fluxes. Similar to the water vapour fluxes, the net ecosystem production decreased with increasing water stress at all the sites. Both gross primary production (GPP) and total ecosystem respiration (TER) also decreased when REW dropped below 0.4 and 0.2, for GPP and TER, respectively. A higher sensitivity to drought was found in the beech, and surprisingly, in the broadleaved Mediterranean forests; the coniferous stands (spruce and pine) appeared to be less drought-sensitive. The effect of drought on tree growth was also large at the three sites where the annual tree growth was measured. Especially in beech, this growth reduction was more pronounced in the year following the drought (2004). Such lag effects on tree growth should be considered an important feature in forest ecosystems, which may enhance vulnerability to more frequent climate extremes.
Quality analysis applied on eddy covariance measurements at complex forest sites using footprint modelling
Rebmann, C. ; Göckede, M. ; Foken, T. ; Aubinet, M. ; Aurela, M. ; Berbigier, P. ; Bernhofer, C. ; Buchmann, N. ; Carrara, A. ; Cescatti, A. ; Ceulemans, R. ; Clement, R. ; Elbers, J.A. ; Granier, A. ; Grünwald, T. ; Guyon, D. ; Havránková, K. ; Heinesch, B. ; Knohl, A. ; Laurila, T. ; Longdoz, B. ; Marcolla, B. ; Markkanen, T. ; Miglietta, F. ; Moncrieff, J. ; Montagnani, L. ; Moors, E.J. ; Nardino, M. ; Ourcival, J.M. ; Rambal, S. ; Rannik, Ü. ; Rotenberg, E. ; Sedlak, P. ; Unterhuber, G. ; Vesala, T. ; Yakir, D. - \ 2005
Theoretical and Applied Climatology 80 (2005). - ISSN 0177-798X - p. 121 - 141.
carbon sequestration - heterogeneous forest - flux measurements - deciduous forest - beech forest - net carbon - exchange - co2 - atmosphere - balance
Measuring turbulent fluxes with the eddy covariance method has become a widely accepted and powerful tool for the determination of long term data sets for the exchange of momentum, sensible and latent heat, and trace gases such as CO2 between the atmosphere and the underlying surface. Several flux networks developed continuous measurements above complex terrain, e.g. AmeriFlux and EUROFLUX, with a strong focus on the net exchange of CO2 between the atmosphere and the underlying surface. Under many conditions basic assumptions for the eddy covariance method in its simplified form, such as stationarity of the flow, homogeneity of the surface and fully developed turbulence of the flow field, are not fulfilled. To deal with non-ideal conditions which are common at many FLUXNET sites, quality tests have been developed to check if these basic theoretical assumptions are valid. In the framework of the CARBOEUROFLUX project, we combined quality tests described by Foken and Wichura (1996) with the analytical footprint model of Schmid (1997). The aim was to identify suitable wind sectors and meteorological conditions for flux measurements. These tools were used on data of 18 participating sites. Quality tests were applied on the fluxes of momentum, sensible and latent heat, and on the CO2-flux, respectively. The influence of the topography on the vertical wind component was also checked. At many sites the land use around the flux towers is not homogeneous or the fetch may not be large enough. So the relative contribution of the land use type intended to be measured was also investigated. Thus the developed tool allows comparative investigations of the measured turbulent fluxes at different sites if using the same technique and algorithms for the determination of the fluxes as well as analyses of potential problems caused by influences of the surrounding land use patterns
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