Manioc : Portail | resultats 1 - 20 pour la recherche: Department of Earth Sciences, University of Oxford

Éditeur(s) : HAL CCSD Wiley
Résumé : The allocation and cycling of carbon (C) within forests is an important component of the biospheric C cycle, but is particularly understudied within tropical forests. We synthesise reported and unpublished results from three lowland rainforest sites in Amazonia (in the regions of Manaus, Tapajos and Caxiuana), all major sites of the Large-Scale Biosphere-Atmosphere Programme (LBA). We attempt a comprehensive synthesis of the C stocks, nutrient status and, particularly, the allocation and internal C dynamics of all three sites. The calculated net primary productivities (NPP) are 10.1 +/- 1.4 Mg C ha(-1) yr(-1) (Manaus), 14.4 +/- 1.3 Mg C ha(-1) yr(-1) (Tapajos) and 10.0 +/- 1.2 Mg C ha(-1) yr(-1) (Caxiuana). All errors bars report standard errors. Soil and leaf nutrient analyses indicate that Tapajos has significantly more plant-available phosphorus and calcium. Autotrophic respiration at all three sites (14.9-21.4 Mg C ha yr(-1)) is more challenging to measure, with the largest component and greatest source of uncertainty being leaf dark respiration. Comparison of measured soil respiration with that predicted from C cycling measurements provides an independent constraint. It shows general good agreement at all three sites, with perhaps some evidence for measured soil respiration being less than expected. Twenty to thirty percent of fixed C is allocated belowground. Comparison of gross primary productivity (GPP), derived from ecosystem flux measurements with that derived from component studies (NPP plus autotrophic respiration) provides an additional crosscheck. The two approaches are in good agreement, giving increased confidence in both approaches to estimating GPP. The ecosystem carbon-use efficiency (CUEs), the ratio of NPP to GPP, is similar at Manaus (0.34 +/- 0.10) and Caxiuana (0.32 +/- 0.07), but may be higher at Tapajos (0.49 +/- 0.16), although the difference is not significant. Old growth or infertile tropical forests may have low CUE compared with recently disturbed and/or fertile forests.
ISSN: 1354-1013

hal-01032150
https://hal.archives-ouvertes.fr/hal-01032150
DOI : 10.1111/j.1365-2486.2008.01780.x

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History of slavery in Connecticut
Auteur(s) : Steiner, Bernard C.
Année de publication :

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CO2 balance of boreal, temperate, and tropical forests derived from a global database
Auteur(s) : Luyssaert, S. INGLIMA, I. Jung, M. RICHARDSON, A. D. Reichstein, M. Papale, D. Piao, S. L. SCHULZE, E. -D.
Auteurs secondaires : Department of Biology ; University of Antwerp (UA) Centre Interdisciplinaire de Recherche Ions Lasers (CIRIL) ; Université de Caen Normandie (UNICAEN) ; Normandie Université (NU) - Normandie Université (NU) - Ecole Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN) ; Normandie Université (NU) - Commissariat à l'énergie atomique et aux énergies alternatives (CEA) - Centre National de la Recherche Scientifique (CNRS) Faculty of Information Sciences and Engineering ; University of Canberra Biogeochemical-Model-Data Integration Group ; Max Planck Institute for Biogeochemistry Department of Forest Environment and Resources ; University of Tuscia Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing 100085, China ; affiliation inconnue Sino-French Institute for Earth System Science, College of Urban and Environmental Sciences, Peking University, Beijing 100871, China ; affiliation inconnue Max-Planck-Institut für Biogeochemie (MPI-BGC)

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Contributions of a global network of tree diversity experiments to sustainable forest plantations
Auteur(s) : Verheyen, Kris Vanhellemont, Margot Auge, Harald Baeten, Lander Baraloto, Christopher Barsoum, Nadia Bilodeau-Gauthier, Simon Bruelheide, Helge
Auteurs secondaires : Forest & Nature Lab, Department of Forest and Water Management ; Ghent University [Belgium] (UGENT) Department of Community Ecology ; Helmholtz Centre for Environmental Research - UFZ (GERMANY) German Institute for Integrative Biodiversity Research (iDiv) Ecologie des forêts de Guyane (ECOFOG) ; Centre de Coopération Internationale en Recherche Agronomique pour le Développement (CIRAD) - Institut National de la Recherche Agronomique (INRA) - Université des Antilles et de la Guyane (UAG) - AgroParisTech - Université de Guyane (UG) - Centre National de la Recherche Scientifique (CNRS) Florida International University (FIU) Department of Botany ; Instituto Nacional de Pesquisas da Amazônia Centre for Ecosystems, Society and Biosecurity ; Forest Research Centre for Forest Research (CFR) ; Université du Québec à Montréal (UQAM)

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Global Positioning System measurements of strain accumulation and slip transfer through the restraining bend along the Dead Sea fault system in Lebanon
Auteur(s) : Gomez, F. Karam, G. Khawlie, M. Mcclusky, S. Vernant, Philippe Reilinger, R. Jaafar, R. Tabet, C.
Auteurs secondaires : Department of Geological Sciences, University of Missouri, Columbia, Missouri ; Université du Québec Department of Civil Engineering, Lebanese American University, Jbail ; Université du Québec Lebanese National Center for Remote Sensing, Beirut ; Université du Québec Massachusetts Institute of Technology (MIT) Géosciences Montpellier ; Université des Antilles et de la Guyane (UAG) - Institut national des sciences de l'Univers (INSU - CNRS) - Université de Montpellier (UM) - Centre National de la Recherche Scientifique (CNRS) Lebanese National Council for Scientific Research, Beirut ; Université du Québec Hasbaya ; Université du Québec Institute for the Study of the Continents, Snee Hall, Cornell University, Ithaca, New York ; Université du Québec

Éditeur(s) : HAL CCSD Oxford University Press (OUP)
Résumé : Approximately 4 yr of campaign and continuous Global Positioning System (GPS) measurements across the Dead Sea fault system (DSFS) in Lebanon provide direct measurements of interseismic strain accumulation along a 200-km-long restraining bend in this continental transform fault. Late Cenozoic transpression within this restraining bend has maintained more than 3000 m of topography in the Mount Lebanon and Anti-Lebanon ranges. The GPS velocity field indicates 4-5 mm yr(-1) of relative plate motion is transferred through the restraining bend to the northern continuation of the DSFS in northwestern Syria. Near-field GPS velocities are generally parallel to the major, left-lateral strike-slip faults, suggesting that much of the expected convergence across the restraining bend is likely accommodated by different structures beyond the aperture of the GPS network (e.g. offshore Lebanon and, possibly, the Palmyride fold belt in SW Syria). Hence, these geodetic results suggest a partitioning of crustal deformation involving strike-slip displacements in the interior of the restraining bend, and crustal shortening in the outer part of the restraining bend. Within the uncertainties, the GPS-based rates of fault slip compare well with Holocene-averaged estimates of slip along the two principal strike-slip faults: the Yammouneh and Serghaya faults. Of these two faults, more slip occurs on the Yammouneh fault, which constitutes the primary plate boundary structure between the Arabia and Sinai plates. Hence, the Yammouneh fault is the structural linkage that transfers slip to the northern part of the transform in northwestern Syria. From the perspective of the regional earthquake hazard, the Yammouneh fault is presently locked and accumulating interseismic strain.
ISSN: 0956-540X

hal-00406620
https://hal.archives-ouvertes.fr/hal-00406620
DOI : 10.1111/j.1365-246X.2006.03328.x

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