scholarly journals Asynchronism in leaf and wood production in tropical forests: a study combining satellite and ground-based measurements

2013 ◽  
Vol 10 (5) ◽  
pp. 8247-8281 ◽  
Author(s):  
F. Wagner ◽  
V. Rossi ◽  
C. Stahl ◽  
D. Bonal ◽  
B. Hérault
Keyword(s):  
Carbon Cycle ◽  
Tropical Forests ◽  
Time Scale ◽  
Carbon Allocation ◽  
Net Primary Production ◽  
Time Lag ◽  
Production Model ◽  
Wood Production ◽  
Modis Evi ◽  
Seasonal Time Scale

Abstract. The fixation of carbon in tropical forests mainly occurs through the production of wood and leaves, both being the principal components of net primary production. Currently field and satellite observations are independently used to describe the forest carbon cycle, but the link between satellite-derived forest phenology and field-derived forest productivity remains opaque. We used a unique combination of a MODIS EVI dataset, a climate-explicit wood production model and direct litterfall observations at an intra-annual time scale in order to question the synchronism of leaf and wood production in tropical forests. Even though leaf and wood biomass fluxes had the same range (respectively 2.4 ± 1.4 Mg C ha−1yr−1 and 2.2 ± 0.4 Mg C ha−1yr−1), they occured separately in time. EVI increased with the magnitude of leaf renewal at the beginning of the dry season when solar irradiance was at its maximum. At this time, wood production stopped. At the onset of the rainy season when new leaves were fully mature and water available again, wood production quickly increased to reach its maximum in less than a month, reflecting a change in carbon allocation from short lived pools (leaves) to long lived pools (wood). The time lag between peaks of EVI and wood production (109 days) revealed a substantial decoupling between the irradiance-driven leaf renewal and the water-driven wood production. Our work is a first attempt to link EVI data, wood production and leaf phenology at a seasonal time scale in a tropical evergreen rainforest and pave the way to develop more sophisticated global carbon cycle models in tropical forests.

scholarly journals Asynchronism in leaf and wood production in tropical forests: a study combining satellite and ground-based measurements

2013 ◽  
Vol 10 (11) ◽  
pp. 7307-7321 ◽  
Author(s):  
F. Wagner ◽  
V. Rossi ◽  
C. Stahl ◽  
D. Bonal ◽  
B. Hérault
Keyword(s):  
Carbon Cycle ◽  
Tropical Forests ◽  
Vegetation Index ◽  
Carbon Allocation ◽  
Net Primary Production ◽  
Time Lag ◽  
Production Model ◽  
Climate Data ◽  
Wood Production ◽  
Global Carbon

Abstract. The fixation of carbon in tropical forests mainly occurs through the production of wood and leaves, both being the principal components of net primary production. Currently field and satellite observations are independently used to describe the forest carbon cycle, but the link between satellite-derived forest phenology and field-derived forest productivity remains opaque. We used a unique combination of a MODIS enhanced vegetation index (EVI) dataset, a wood production model based on climate data and direct litterfall observations at an intra-annual timescale in order to question the synchronism of leaf and wood production in tropical forests. Even though leaf and wood biomass fluxes had the same range (respectively 2.4 ± 1.4 and 2.2 ± 0.4 Mg C ha−1 yr−1), they occurred separately in time. EVI increased with leaf renewal at the beginning of the dry season, when solar irradiance was at its maximum. At this time, wood production stopped. At the onset of the rainy season, when new leaves were fully mature and water available again, wood production quickly increased to reach its maximum in less than a month, reflecting a change in carbon allocation from short-lived pools (leaves) to long-lived pools (wood). The time lag between peaks of EVI and wood production (109 days) revealed a substantial decoupling between the leaf renewal assumed to be driven by irradiance and the water-driven wood production. Our work is a first attempt to link EVI data, wood production and leaf phenology at a seasonal timescale in a tropical evergreen rainforest and pave the way to develop more sophisticated global carbon cycle models in tropical forests.

Variations of carbon allocation and turnover time across tropical forests

2021 ◽  
Author(s):  
Hui Yang ◽  
Philippe Ciais ◽  
Yilong Wang ◽  
Yuanyuan Huang ◽  
Jean‐Pierre Wigneron ◽  
...  
Keyword(s):  
Tropical Forests ◽  
Carbon Allocation ◽  
Turnover Time

scholarly journals Millennium time-scale experiments on climate-carbon cycle with doubled CO2 concentration

2020 ◽  
Vol 7 (1) ◽  
Author(s):  
Tomohiro Hajima ◽  
Akitomo Yamamoto ◽  
Michio Kawamiya ◽  
Xuanming Su ◽  
Michio Watanabe ◽  
...  
Keyword(s):  
Carbon Cycle ◽  
Time Scale ◽  
Co2 Concentration ◽  
Doubled Co2 Concentration

scholarly journals Lianas reduce carbon accumulation and storage in tropical forests

2015 ◽  
Vol 112 (43) ◽  
pp. 13267-13271 ◽  
Author(s):  
Geertje M. F. van der Heijden ◽  
Jennifer S. Powers ◽  
Stefan A. Schnitzer
Keyword(s):  
Tropical Forests ◽  
Large Scale ◽  
Net Primary Production ◽  
Carbon Dynamics ◽  
Carbon Accumulation ◽  
Carbon Uptake ◽  
Woody Vines ◽  
Significant Difference ◽  
Agent Of Change ◽  
The Impact

Tropical forests store vast quantities of carbon, account for one-third of the carbon fixed by photosynthesis, and are a major sink in the global carbon cycle. Recent evidence suggests that competition between lianas (woody vines) and trees may reduce forest-wide carbon uptake; however, estimates of the impact of lianas on carbon dynamics of tropical forests are crucially lacking. Here we used a large-scale liana removal experiment and found that, at 3 y after liana removal, lianas reduced net above-ground carbon uptake (growth and recruitment minus mortality) by ∼76% per year, mostly by reducing tree growth. The loss of carbon uptake due to liana-induced mortality was four times greater in the control plots in which lianas were present, but high variation among plots prevented a significant difference among the treatments. Lianas altered how aboveground carbon was stored. In forests where lianas were present, the partitioning of forest aboveground net primary production was dominated by leaves (53.2%, compared with 39.2% in liana-free forests) at the expense of woody stems (from 28.9%, compared with 43.9%), resulting in a more rapid return of fixed carbon to the atmosphere. After 3 y of experimental liana removal, our results clearly demonstrate large differences in carbon cycling between forests with and without lianas. Combined with the recently reported increases in liana abundance, these results indicate that lianas are an important and increasing agent of change in the carbon dynamics of tropical forests.

scholarly journals New insights into carbon allocation by trees from the hypothesis that annual wood production is maximized

2013 ◽  
Vol 199 (4) ◽  
pp. 981-990 ◽  
Author(s):  
Ross E. McMurtrie ◽  
Roderick C. Dewar
Keyword(s):  
Carbon Allocation ◽  
Wood Production

scholarly journals Challenges to Reproduce Vegetation Structure and Dynamics in Amazonia Using a Coupled Climate–Biosphere Model

2009 ◽  
Vol 13 (11) ◽  
pp. 1-28 ◽  
Author(s):  
Mônica Carneiro Alves Senna ◽  
Marcos Heil Costa ◽  
Lucía Iracema Chipponelli Pinto ◽  
Hewlley Maria Acioli Imbuzeiro ◽  
Luciana Mara Freitas Diniz ◽  
...  
Keyword(s):  
Vegetation Structure ◽  
Carbon Allocation ◽  
Net Primary Production ◽  
Ecosystem Structure ◽  
Intergovernmental Panel ◽  
Area Index ◽  
Carbon Cycle Model ◽  
Accurate Representation ◽  
Structure And Dynamics ◽  
Biosphere Model

Abstract The Amazon rain forest constitutes one of the major global stocks of carbon. Recent studies, including the last Intergovernmental Panel on Climate Change report and the Coupled Climate Carbon Cycle Model Intercomparison Project, have suggested that it may reduce in size and lose biomass during the twenty-first century through a savannization process. A better understanding of how this ecosystem structure, dynamics, and carbon balance may respond to future climate changes is needed. This article investigates how well a fully coupled atmosphere–biosphere model can reproduce vegetation structure and dynamics in Amazonia to the extent permitted by available data. The accurate representation of the coupled climate–biosphere dynamics requires the accurate representation of climate, net primary production (NPP), and its partition among the several carbon pool components. The simulated climate is validated against precipitation (within 5% of four datasets) and incident solar radiation (within 7% of observations). The authors also validate (i) simulated land cover, which reproduces well the observed patterns; (ii) NPP, within 5% of observations; and (iii) respiration rates, within 15% of observations. The performance of simulated variables that depend on carbon allocation, like NPP partitioning, leaf area index, and aboveground live biomass, although good on a regional mean, is significantly low when spatial patterns are considered. These errors may be attributed to fixed carbon allocation and residence time parameters assumed by the model. Carbon allocation apparently varies spatially, and to simulate this spatial variability is quite a challenge.

An attempt to understand δ13C cycles with a simple conceptual model.

2021 ◽  
Author(s):  
Gaelle Leloup ◽  
Didier Paillard
Keyword(s):  
Organic Matter ◽  
Carbon Cycle ◽  
Conceptual Model ◽  
Carbon Isotope ◽  
Time Scale ◽  
Marine Biology ◽  
Climate Modelling ◽  
Orbital Eccentricity ◽  
Sediment Data ◽  
Geomagnetic Polarity

<div> <div> <p>A correct understanding of the human perturbation on the carbon cycle is a fundamental prerequisite of future climate modelling on large timescales.</p> <p>However, « classical » carbon cycle theories barely take into account the « organic » part of the carbon cycle and are not able to reproduce past δ<sup>13</sup>C data.</p> <p>Analysis of sediment data reveals the presence of cycles in the δ<sup>13</sup>C record. A 400 kyr cycle has been observed at several time periods, from the Eocene to present [1-4]. Moreover, longer cycles have been observed : 2.4, 4.6 and 9 Myr [5-8]. The 9 Myr cycle is present since the start of the Mesozoic. These periodicities seem linked to eccentricity periods.</p> <p>By forcing astronomically the (net) organic matter burial in a carbon cycle conceptual model, Paillard [9] reproduced 400 kyr and 2.4 Myr cycles in δ<sup>13</sup>C.</p> <p>The net organic matter burial has a key role on δ<sup>13</sup>C, as terrestrial and marine biology preferentially use <sup>12</sup>C during photosynthesis. Therefore if the burial of (<sup>12</sup>C rich) organic matter is relatively more important, the δ<sup>13</sup>C of the superficial system will decrease, and inversely.</p> <p>However, this conceptual model was not able to explain longer term cycles at 4.6 and 9 Myr.</p> <p>Here, we develop a new conceptual model based on Paillard [9], which includes the role of oxygen. Indeed, oxygen also influences the organic matter burial.</p> <p>With this new conceptual model coupling carbon and oxygen cycle, it is possible to obtain 400 kyr, 2.4 Myr, but also longer cycles.</p> <p> </p> <p>References :</p> <p>[1] Sexton et al, 2011, Eocene global warming events driven by ventilation of oceanic dissolved organic carbon</p> <p>[2] Pälike et al, 2006 The Heartbeat of the Oligocene Climate System</p> <p>[3] Billups et al, 2004 Astronomic calibration of the late Oligocene through early Miocene geomagnetic polarity time scale</p> <p>[4]Wang et al, 2010, Obscuring of long eccentricity cyclicity in Pleistocene oceanic carbon isotope records</p> <p>[5] Boulila et al, 2012, A ~9 myr cycle in Cenozoic δ13C record and long-term orbital eccentricity modulation: Is there a link?</p> <p>[6] Ikeda et al, 2014, 70 million year astronomical time scale for the deep-sea bedded chert sequence (Inuyama, Japan): Implications for Triassic–Jurassic geochronology.</p> <p>[7] Martinez et al, 2015, Orbital pacing of carbon fluxes by a ∼9-My eccentricity cycle during the Mesozoic</p> <p>[8] Sprovieri M, et al. (2013) Late Cretaceous orbitally-paced carbon isotope stratigraphy from the Bottaccione Gorge (Italy).</p> <p>[9] Paillard, 2017, The Plio-Pleistocene climatic evolution as a consequence of orbital forcing on the carbon cycle.</p> </div> </div>

scholarly journals Diagnosis of CO2 dynamics and fluxes in global coastal oceans

2019 ◽  
Vol 7 (4) ◽  
pp. 786-797 ◽  
Author(s):  
Zhimian Cao ◽  
Wei Yang ◽  
Yangyang Zhao ◽  
Xianghui Guo ◽  
Zhiqiang Yin ◽  
...  
Keyword(s):  
Carbon Cycle ◽  
Dissolved Inorganic Carbon ◽  
Net Primary Production ◽  
Carbon Sink ◽  
Analytical Framework ◽  
Coastal System ◽  
Coastal Oceans ◽  
Co2 Dynamics ◽  
Earth System Models

Abstract Global coastal oceans as a whole represent an important carbon sink but, due to high spatial–temporal variability, a mechanistic conceptualization of the coastal carbon cycle is still under development, hindering the modelling and inclusion of coastal carbon in Earth System Models. Although temperature is considered an important control of sea surface pCO2, we show that the latitudinal distribution of global coastal surface pCO2 does not match that of temperature, and its inter-seasonal changes are substantially regulated by non-thermal factors such as water mass mixing and net primary production. These processes operate in both ocean-dominated and river-dominated margins, with carbon and nutrients sourced from the open ocean and land, respectively. These can be conceptualized by a semi-analytical framework that assesses the consumption of dissolved inorganic carbon relative to nutrients, to determine how a coastal system is a CO2 source or sink. The framework also finds utility in accounting for additional nutrients in organic forms and testing hypotheses such as using Redfield stoichiometry, and is therefore an essential step toward comprehensively understanding and modelling the role of the coastal ocean in the global carbon cycle.

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