|Multi-site evaluation of the MOD17 model over homogeneous agricultural vegetation
Gelybó, G. ; Barcza, Z. ; Kern, A. ; Alberti, G. ; tommasi, P. Di; Elbers, J.A. ; Fischer, M. ; Gonzalez-Meler, M. ; Griffis, T. ; Kutsch, W.L. ; Magliulo, E. ; Matamala, R. ; Moors, E.J. ; Peressotti, A. ; Suyker, A.E. ; Verma, S.B. - \ 2010
Mycorrhizal hyphal turnover as a dominant process for carbon input into soil organic matter
Godbold, D. ; Hoosbeek, M.R. ; Lukac, M. ; Francesca Cotrufo, M. ; Janssens, I.A. ; Ceulemans, R. ; Polle, A. ; Velthorst, E.J. ; Scarascia-Mugnozza, G. ; Angelis, P. de; Miglietta, F. ; Peressotti, A. - \ 2006
Plant and Soil 281 (2006)1-2. - ISSN 0032-079X - p. 15 - 24.
elevated atmospheric co2 - douglas-fir ecosystem - 1st growing-season - ectomycorrhizal fungi - forest ecosystems - external mycelium - root turnover - enrichment - nitrogen - patterns
The atmospheric concentration of CO2 is predicted to reach double current levels by 2075. Detritus from aboveground and belowground plant parts constitutes the primary source of C for soil organic matter (SOM), and accumulation of SOM in forests may provide a significant mechanism to mitigate increasing atmospheric CO2 concentrations. In a poplar (three species) plantation exposed to ambient (380 ppm) and elevated (580 ppm) atmospheric CO2 concentrations using a Free Air Carbon Dioxide Enrichment (FACE) system, the relative importance of leaf litter decomposition, fine root and fungal turnover for C incorporation into SOM was investigated. A technique using cores of soil in which a C-4 crop has been grown (delta C-13 -18.1 parts per thousand) inserted into the plantation and detritus from C-3 trees (delta C-13 -27 to -30 parts per thousand) was used to distinguish between old (native soil) and new (tree derived) soil C. In-growth cores using a fine mesh (39 mu m) to prevent in-growth of roots, but allow in-growth of fungal hyphae were used to assess contribution of fine roots and the mycorrhizal external mycelium to soil C during a period of three growing seasons (1999-2001). Across all species and treatments, the mycorrhizal external mycelium was the dominant pathway (62%) through which carbon entered the SOM pool, exceeding the input via leaf litter and fine root turnover. The input via the mycorrhizal external mycelium was not influenced by elevated CO2, but elevated atmospheric CO2 enhanced soil C inputs via fine root turnover. The turnover of the mycorrhizal external mycelium may be a fundamental mechanism for the transfer of root-derived C to SOM.
Comparison between tower and aircraft-based eddy covariance fluxes in five European regions
Gioli, B. ; Miglietta, F. ; Martino, B. De; Hutjes, R.W.A. ; Dolman, A.J. ; Lindroth, A. ; Schumacher, M. ; Sanz, M.J. ; Manca, G. ; Peressotti, A. ; Dumas, E.J. - \ 2004
Agricultural and Forest Meteorology 127 (2004)1-2. - ISSN 0168-1923 - p. 1 - 16.
atmospheric boundary-layer - carbon-dioxide - water-vapor - boreal forest - sensible heat - latent-heat - co2 - footprint - exchange - fluxnet
Airborne eddy covariance measurements provide a unique opportunity to directly measure surface energy, mass and momentum fluxes at the regional scale. This offers the possibility to complement the data that are obtained by the ground-based eddy covariance networks and to validate estimates of the surface fluxes that can be obtained by means of satellite products and models. The overall accuracy and the reliability of airborne eddy covariance measurements have already been assessed in the past for different platforms. More recently an international collaboration between several research laboratories and a European aeronautical manufacturer led to the development of a new small environmental research aircraft, called the Sky Arrow ERA (Environmental Research Aircraft). This aircraft has been used in the framework of the European Research Project RECAB (Regional Assessment and Modelling of the Carbon Balance in Europe), that is part of the CarboEurope projects cluster, to measure surface mass and energy exchange at five different European locations. An extensive comparison between airborne and ground-based flux data at seven flux measurement sites, showed the overall matching between airborne and tower data. While friction velocity and latent heat flux estimates made by airborne and tower data were comparable at all sites and under whatever conditions, substantial and consistent underestimation of CO2 (28% on average) and sensible heat fluxes (35% on average) was observed. Differences in the aircraft and tower footprint and flux divergence with height explained most of the discrepancies.
More new carbon in the mineral soil of a poplar plantation under Free Air Carbon Erichment (POPFACE): Cause of increased priming effect?
Hoosbeek, M.R. ; Lukac, M. ; Dam, D. ; Godbold, D. ; Velthorst, E.J. ; Bondi, F.A. ; Peressotti, A. ; Cotrufo, M.F. ; Angelis, P. de; Scarascia-Mugnozza, G. - \ 2004
Global Biogeochemical Cycles 18 (2004)1. - ISSN 0886-6236 - 7 p.
elevated atmospheric co2 - organic-matter - terrestrial ecosystems - turnover - forest - storage - system - decomposition - mechanisms - feedbacks
 In order to establish suitability of forest ecosystems for long-term storage of C, it is necessary to characterize the effects of predicted increased atmospheric CO2 levels on the pools and fluxes of C within these systems. Since most C held in terrestrial ecosystems is in the soil, we assessed the influence of Free Air Carbon Enrichment (FACE) treatment on the total soil C content (C-total) and incorporation of litter derived C (C-new) into soil organic matter (SOM) in a fast growing poplar plantation. C-new was estimated by the C3/C4 stable isotope method. C-total contents increased under control and FACE respectively by 12 and 3%, i.e., 484 and 107 gC/m(2), while 704 and 926 gC/m(2) of new carbon was sequestered under control and FACE during the experiment. We conclude that FACE suppressed the increase of C-total and simultaneously increased C-new. We hypothesize that these opposite effects may be caused by a priming effect of the newly incorporated litter, where priming effect is defined as the stimulation of SOM decomposition caused by the addition of labile substrates.
|More new carbon in the mineral soil if a popular plantation under FACE (POPFACE)
Hoosbeek, M.R. ; Lukac, M. ; Dam, D. ; Godbold, D. ; Velthorst, E.J. ; Biondi, F.A. ; Peressotti, A. ; Gotrufo, M.F. ; Angelis, P. de; Scarascia-Mugnozza, G. - \ 2004