Showing papers by "Robert Clement published in 2001"
University of California, Berkeley1, Oak Ridge National Laboratory2, Oregon State University3, Gembloux Agro-Bio Tech4, Dresden University of Technology5, University of Nebraska–Lincoln6, University of Antwerp7, Institut national de la recherche agronomique8, United States Forest Service9, Duke University10, University of Edinburgh11, Harvard University12, University of Helsinki13, Max Planck Society14, University of Bayreuth15, University of New Hampshire16
TL;DR: In this paper, the impact of different gap filling methods on the annual sum of net ecosystem exchange (F NEE ) responses is investigated, based on mean diurnal variation, look-up tables (LookUp), and nonlinear regressions (Regr).
1,717 citations
University of Antwerp1, Lund University2, Max Planck Society3, University of Franche-Comté4, University of Kiel5, Gembloux Agro-Bio Tech6, Dresden University of Technology7, University of Padua8, University of Helsinki9, University of Göttingen10, University of Edinburgh11, United States Forest Service12, Institut national de la recherche agronomique13
TL;DR: In this article, the authors presented CO2 flux data from 18 forest ecosystems, studied in the European Union funded EUROFLUX project, and observed a significant correlation was observed between annual soil respiration (SR) and gross primary productivity (GPP) among the relatively undisturbed forests.
Abstract: Summary
This paper presents CO2 flux data from 18 forest ecosystems, studied in the European Union funded EUROFLUX project. Overall, mean annual gross primary productivity (GPP, the total amount of carbon (C) fixed during photosynthesis) of these forests was 1380 ± 330 gC m−2 y−1 (mean ±SD). On average, 80% of GPP was respired by autotrophs and heterotrophs and released back into the atmosphere (total ecosystem respiration, TER = 1100 ± 260 gC m−2 y−1). Mean annual soil respiration (SR) was 760 ± 340 gC m−2 y−1 (55% of GPP and 69% of TER).
Among the investigated forests, large differences were observed in annual SR and TER that were not correlated with mean annual temperature. However, a significant correlation was observed between annual SR and TER and GPP among the relatively undisturbed forests. On the assumption that (i) root respiration is constrained by the allocation of photosynthates to the roots, which is coupled to productivity, and that (ii) the largest fraction of heterotrophic soil respiration originates from decomposition of young organic matter (leaves, fine roots), whose availability also depends on primary productivity, it is hypothesized that differences in SR among forests are likely to depend more on productivity than on temperature.
At sites where soil disturbance has occurred (e.g. ploughing, drainage), soil espiration was a larger component of the ecosystem C budget and deviated from
the relationship between annual SR (and TER) and GPP observed among the less-disturbed forests. At one particular forest, carbon losses from the soil were so large, that in some years the site became a net source of carbon to the atmosphere. Excluding the disturbed sites from the present analysis reduced mean SR to 660 ± 290 gC m−2 y−1, representing 49% of GPP and 63% of TER in the relatively undisturbed forest ecosystems.
958 citations
University of California, Berkeley1, Oak Ridge National Laboratory2, Oregon State University3, Dresden University of Technology4, University of Nebraska–Lincoln5, University of Antwerp6, University of Edinburgh7, Institut national de la recherche agronomique8, United States Forest Service9, Duke University10, University of Helsinki11, Harvard University12, Max Planck Society13, University of Bayreuth14, University of New Hampshire15
TL;DR: In this article, the authors adapted methods of gap filling for NEE (net ecosystem exchange of carbon) to energy fluxes and applied them to data sets available from the EUROFLUX and AmeriFlux eddy covariance databases.
531 citations
University of Edinburgh1, Wageningen University and Research Centre2, Max Planck Society3, University of Antwerp4, Institut national de la recherche agronomique5, Lund University6, Swedish University of Agricultural Sciences7, Dresden University of Technology8, Gembloux Agro-Bio Tech9, University of Helsinki10, University of Göttingen11
TL;DR: In this article, the authors respond to the Forum contribution by Piovesan & Adams (2000) who criticized the results obtained by the EUROFLUX network on carbon fluxes of several European forests.
Abstract: 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.
22 citations