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Schwalm, C.R.; Williams, C.A.; Schaefer, K.; Arneth, A.; Bonal, D.; Buchmann, N.; Chen, J.Q.; Law, B.E.; Lindroth, A.; Luyssaert, S.; Reichstein, M.; Richardson, A.D. |
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Title |
Assimilation exceeds respiration sensitivity to drought: A FLUXNET synthesis |
Type |
Journal Article |
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Year |
2010 |
Publication  |
Global Change Biology |
Abbreviated Journal |
Glob. Change Biol. |
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Volume |
16 |
Issue |
2 |
Pages |
657-670 |
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Keywords |
biome; carbon cycling; drought; eddy covariance; evaporative fraction; FLUXNET; synthesis |
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Abstract |
The intensification of the hydrological cycle, with an observed and modeled increase in drought incidence and severity, underscores the need to quantify drought effects on carbon cycling and the terrestrial sink. FLUXNET, a global network of eddy covariance towers, provides dense data streams of meteorological data, and through flux partitioning and gap filling algorithms, estimates of net ecosystem productivity (F-NEP), gross ecosystem productivity (P), and ecosystem respiration (R). We analyzed the functional relationship of these three carbon fluxes relative to evaporative fraction (EF), an index of drought and site water status, using monthly data records from 238 micrometeorological tower sites distributed globally across 11 biomes. The analysis was based on relative anomalies of both EF and carbon fluxes and focused on drought episodes by biome and climatic season. Globally P was approximate to 50% more sensitive to a drought event than R. Network-wide drought-induced decreases in carbon flux averaged -16.6 and -9.3 g C m-2 month-1 for P and R, i.e., drought events induced a net decline in the terrestrial sink. However, in evergreen forests and wetlands drought was coincident with an increase in P or R during parts of the growing season. The most robust relationships between carbon flux and EF occurred during climatic spring for F-NEP and in climatic summer for P and R. Upscaling flux sensitivities to a global map showed that spatial patterns for all three carbon fluxes were linked to the distribution of croplands. Agricultural areas exhibited the highest sensitivity whereas the tropical region had minimal sensitivity to drought. Combining gridded flux sensitivities with their uncertainties and the spatial grid of FLUXNET revealed that a more robust quantification of carbon flux response to drought requires additional towers in all biomes of Africa and Asia as well as in the cropland, shrubland, savannah, and wetland biomes globally. |
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[Schwalm, Christopher R.; Williams, Christopher A.] Clark Univ, Grad Sch Geog, Worcester, MA 01610 USA, Email: cschwalm@clarku.edu |
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WILEY-BLACKWELL PUBLISHING, INC |
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1354-1013 |
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ISI:000274419400014 |
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EcoFoG @ eric.marcon @ |
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69 |
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Fisher, J.B.; Malhi, Y.; Bonal, D.; Da Rocha, H.R.; De Araujo, A.C.; Gamo, M.; Goulden, M.L.; Hirano, T.; Huete, A.R.; Kondo, H.; Kumagai, T.; Loescher, H.W.; Miller, S.; Nobre, A.D.; Nouvellon, Y.; Oberbauer, S.F.; Panuthai, S.; Roupsard, O.; Saleska, S.; Tanaka, K.; Tanaka, N.; Tu, K.P.; Von Randow, C. |
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Title |
The land-atmosphere water flux in the tropics |
Type |
Journal Article |
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Year |
2009 |
Publication |
Global Change Biology |
Abbreviated Journal |
Glob. Change Biol. |
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Volume |
15 |
Issue |
11 |
Pages |
2694-2714 |
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Keywords |
Amazon; eddy covariance; evaporation; evapotranspiration; ISLSCP-II; LBA; model; remote sensing; tropical |
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Abstract |
Tropical vegetation is a major source of global land surface evapotranspiration, and can thus play a major role in global hydrological cycles and global atmospheric circulation. Accurate prediction of tropical evapotranspiration is critical to our understanding of these processes under changing climate. We examined the controls on evapotranspiration in tropical vegetation at 21 pan-tropical eddy covariance sites, conducted a comprehensive and systematic evaluation of 13 evapotranspiration models at these sites, and assessed the ability to scale up model estimates of evapotranspiration for the test region of Amazonia. Net radiation was the strongest determinant of evapotranspiration (mean evaporative fraction was 0.72) and explained 87% of the variance in monthly evapotranspiration across the sites. Vapor pressure deficit was the strongest residual predictor (14%), followed by normalized difference vegetation index (9%), precipitation (6%) and wind speed (4%). The radiation-based evapotranspiration models performed best overall for three reasons: (1) the vegetation was largely decoupled from atmospheric turbulent transfer (calculated from X decoupling factor), especially at the wetter sites; (2) the resistance-based models were hindered by difficulty in consistently characterizing canopy (and stomatal) resistance in the highly diverse vegetation; (3) the temperature-based models inadequately captured the variability in tropical evapotranspiration. We evaluated the potential to predict regional evapotranspiration for one test region: Amazonia. We estimated an Amazonia-wide evapotranspiration of 1370 mm yr(-1), but this value is dependent on assumptions about energy balance closure for the tropical eddy covariance sites; a lower value (1096 mm yr(-1)) is considered in discussion on the use of flux data to validate and interpolate models. |
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[Fisher, Joshua B.; Malhi, Yadvinder] Univ Oxford, Environm Change Inst, Sch Geog & Environm, Oxford OX1 3QY, England, Email: joshbfisher@gmail.com |
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WILEY-BLACKWELL PUBLISHING, INC |
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1354-1013 |
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ISI:000270662000011 |
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EcoFoG @ eric.marcon @ |
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101 |
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Malhi, Y.; Aragao, L.E.O.C.; Metcalfe, D.B.; Paiva, R.; Quesada, C.A.; Almeida, S.; Anderson, L.; Brando, P.; Chambers, J.Q.; da Costa, A.C.L.; Hutyra, L.R.; Oliveira, P.; Patino, S.; Pyle, E.H.; Robertson, A.L.; Teixeira, L.M. |
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Title |
Comprehensive assessment of carbon productivity, allocation and storage in three Amazonian forests |
Type |
Journal Article |
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Year |
2009 |
Publication |
Global Change Biology |
Abbreviated Journal |
Glob. Change Biol. |
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Volume |
15 |
Issue |
5 |
Pages |
1255-1274 |
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Keywords |
allocation; Amazonia; carbon; growth; litterfall; productivity; respiration; roots; soil; tropical forest |
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Abstract |
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. |
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[Malhi, Yadvinder; Aragao, Luiz Eduardo O. C.; Metcalfe, Daniel B.; Anderson, Liana] Sch Geog & Environm, Environm Change Inst, Oxford OX1 3QY, England, Email: yadvinder.malhi@ouce.ox.ac.uk |
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WILEY-BLACKWELL PUBLISHING, INC |
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1354-1013 |
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ISI:000265033700015 |
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no |
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EcoFoG @ eric.marcon @ |
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117 |
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Bonal, D.; Bosc, A.; Ponton, S.; Goret, J.Y.; Burban, B.; Gross, P.; Bonnefond, J.M.; Elbers, J.; Longdoz, B.; Epron, D.; Guehl, J.M.; Granier, A. |
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Title |
Impact of severe dry season on net ecosystem exchange in the Neotropical rainforest of French Guiana |
Type |
Journal Article |
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Year |
2008 |
Publication |
Global Change Biology |
Abbreviated Journal |
Glob. Change Biol. |
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Volume |
14 |
Issue |
8 |
Pages |
1917-1933 |
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Keywords |
dry season; ecosystem respiration; eddy covariance; gross ecosystem productivity; Neotropical rainforest; net ecosystem productivity; soil drought; solar radiation |
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Abstract |
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 (R-Ed) and daily gross ecosystem productivity (GEP(d)), were estimated over 2 years at a flux tower site in French Guiana, South America (5 degrees 16'54'N, 52 degrees 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 R-Ed 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 R-Ed, 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. |
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[Bonal, Damien; Goret, Jean-Yves; Burban, Benoit] INRA, UMR Ecol Forets Guyane, Kourou 97387, French Guiana, Email: damien.bonal@kourou.cirad.fr |
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BLACKWELL PUBLISHING |
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1354-1013 |
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ISI:000257712400015 |
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no |
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EcoFoG @ eric.marcon @ |
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133 |
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Author |
Luyssaert, S.; Inglima, I.; Jung, M.; Richardson, A.D.; Reichsteins, M.; Papale, D.; Piao, S.L.; Schulzes, E.D.; Wingate, L.; Matteucci, G.; Aragao, L.; Aubinet, M.; Beers, C.; Bernhoffer, C.; Black, K.G.; Bonal, D.; Bonnefond, J.M.; Chambers, J.; Ciais, P.; Cook, B.; Davis, K.J.; Dolman, A.J.; Gielen, B.; Goulden, M.; Grace, J.; Granier, A.; Grelle, A.; Griffis, T.; Grunwald, T.; Guidolotti, G.; Hanson, P.J.; Harding, R.; Hollinger, D.Y.; Hutyra, L.R.; Kolar, P.; Kruijt, B.; Kutsch, W.; Lagergren, F.; Laurila, T.; Law, B.E.; Le Maire, G.; Lindroth, A.; Loustau, D.; Malhi, Y.; Mateus, J.; Migliavacca, M.; Misson, L.; Montagnani, L.; Moncrieff, J.; Moors, E.; Munger, J.W.; Nikinmaa, E.; Ollinger, S.V.; Pita, G.; Rebmann, C.; Roupsard, O.; Saigusa, N.; Sanz, M.J.; Seufert, G.; Sierra, C.; Smith, M.L.; Tang, J.; Valentini, R.; Vesala, T.; Janssens, I.A. |
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Title |
CO2 balance of boreal, temperate, and tropical forests derived from a global database |
Type |
Journal Article |
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Year |
2007 |
Publication |
Global Change Biology |
Abbreviated Journal |
Glob. Change Biol. |
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Volume |
13 |
Issue |
12 |
Pages |
2509-2537 |
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Keywords |
carbon cycle; CO2; forest ecosystems; global database; gross primary productivity; net ecosystem productivity; net primary productivity |
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Abstract |
Terrestrial ecosystems sequester 2.1 Pg of atmospheric carbon annually. A large amount of the terrestrial sink is realized by forests. However, considerable uncertainties remain regarding the fate of this carbon over both short and long timescales. Relevant data to address these uncertainties are being collected at many sites around the world, but syntheses of these data are still sparse. To facilitate future synthesis activities, we have assembled a comprehensive global database for forest ecosystems, which includes carbon budget variables (fluxes and stocks), ecosystem traits (e.g. leaf area index, age), as well as ancillary site information such as management regime, climate, and soil characteristics. This publicly available database can be used to quantify global, regional or biome-specific carbon budgets; to re-examine established relationships; to test emerging hypotheses about ecosystem functioning [e.g. a constant net ecosystem production (NEP) to gross primary production (GPP) ratio]; and as benchmarks for model evaluations. In this paper, we present the first analysis of this database. We discuss the climatic influences on GPP, net primary production (NPP) and NEP and present the CO2 balances for boreal, temperate, and tropical forest biomes based on micrometeorological, ecophysiological, and biometric flux and inventory estimates. Globally, GPP of forests benefited from higher temperatures and precipitation whereas NPP saturated above either a threshold of 1500 mm precipitation or a mean annual temperature of 10 degrees C. The global pattern in NEP was insensitive to climate and is hypothesized to be mainly determined by nonclimatic conditions such as successional stage, management, site history, and site disturbance. In all biomes, closing the CO2 balance required the introduction of substantial biome-specific closure terms. Nonclosure was taken as an indication that respiratory processes, advection, and non-CO2 carbon fluxes are not presently being adequately accounted for. |
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Univ Antwerp, Dept Biol, B-2610 Antwerp, Belgium, Email: Sebastiaan.Luyssaert@ua.ac.be |
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BLACKWELL PUBLISHING |
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1354-1013 |
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ISI:000251049000004 |
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EcoFoG @ eric.marcon @ |
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151 |
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Gloor, M.; Phillips, O.L.; Lloyd, J.J.; Lewis, S.L.; Malhi, Y.; Baker, T.R.; Lopez-Gonzalez, G.; Peacock, J.; Almeida, S.; de Oliveira, A.C.A.; Alvarez, E.; Amaral, I.; Arroyo, L.; Aymard, G.; Banki, O.; Blanc, L.; Bonal, D.; Brando, P.; Chao, K.J.; Chave, J.; Davila, N.; Erwin, T.; Silva, J.; Di Fiore, A.; Feldpausch, T.R.; Freitas, A.; Herrera, R.; Higuchi, N.; Honorio, E.; Jimenez, E.; Killeen, T.; Laurance, W.; Mendoza, C.; Monteagudo, A.; Andrade, A.; Neill, D.; Nepstad, D.; Vargas, P.N.; Penuela, M.C.; Cruz, A.P.; Prieto, A.; Pitman, N.; Quesada, C.; Salomao, R.; Silveira, M.; Schwarz, M.; Stropp, J.; Ramirez, F.; Ramirez, H.; Rudas, A.; ter Steege, H.; Silva, N.; Torres, A.; Terborgh, J.; Vasquez, R.; van der Heijden, G. |
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Title |
Does the disturbance hypothesis explain the biomass increase in basin-wide Amazon forest plot data? |
Type |
Journal Article |
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Year |
2009 |
Publication |
Global Change Biology |
Abbreviated Journal |
Glob. Change Biol. |
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Volume |
15 |
Issue |
10 |
Pages |
2418-2430 |
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Keywords |
Amazon rainforest; carbon sink; disturbance; mortality; power law |
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Positive aboveground biomass trends have been reported from old-growth forests across the Amazon basin and hypothesized to reflect a large-scale response to exterior forcing. The result could, however, be an artefact due to a sampling bias induced by the nature of forest growth dynamics. Here, we characterize statistically the disturbance process in Amazon old-growth forests as recorded in 135 forest plots of the RAINFOR network up to 2006, and other independent research programmes, and explore the consequences of sampling artefacts using a data-based stochastic simulator. Over the observed range of annual aboveground biomass losses, standard statistical tests show that the distribution of biomass losses through mortality follow an exponential or near-identical Weibull probability distribution and not a power law as assumed by others. The simulator was parameterized using both an exponential disturbance probability distribution as well as a mixed exponential-power law distribution to account for potential large-scale blowdown events. In both cases, sampling biases turn out to be too small to explain the gains detected by the extended RAINFOR plot network. This result lends further support to the notion that currently observed biomass gains for intact forests across the Amazon are actually occurring over large scales at the current time, presumably as a response to climate change. |
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[Gloor, M.; Phillips, O. L.; Lloyd, J. J.; Lewis, S. L.; Baker, T. R.; Lopez-Gonzalez, G.; Peacock, J.; Feldpausch, T. R.] Univ Leeds, Sch Geog, Leeds LS2 9JT, W Yorkshire, England, Email: eugloor@googlemail.com |
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WILEY-BLACKWELL PUBLISHING, INC |
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1354-1013 |
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ISI:000269577800006 |
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EcoFoG @ eric.marcon @ |
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196 |
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Ponton, S.; Flanagan, L.B.; Alstad, K.P.; Johnson, B.G.; Morgenstern, K.; Kljun, N.; Black, T.A.; Barr, A.G. |
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Title |
Comparison of ecosystem water-use efficiency among Douglas-fir forest, aspen forest and grassland using eddy covariance and carbon isotope techniques |
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Journal Article |
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Year |
2006 |
Publication |
Global Change Biology |
Abbreviated Journal |
Glob. Change Biol. |
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Volume |
12 |
Issue |
2 |
Pages |
294-310 |
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Keywords |
boreal forest; conifer forest; eddy covariance; grassland; stable isotopes |
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Abstract |
Comparisons were made among Douglas-fir forest, aspen (broad leaf deciduous) forest and wheatgrass (C-3) grassland for ecosystem-level water-use efficiency (WUE). WUE was defined as the ratio of photosynthetic CO2 assimilation rate and evapotranspiration (ET) rate. The ET data measured by eddy covariance were screened so that they overwhelmingly represented transpiration. The three sites used in this comparison spanned a range of vegetation (plant functional) types and environmental conditions within western Canada. When compared in the relative order Douglas-fir (located on Vancouver Island, BC), aspen (northern Saskatchewan), grassland (southern Alberta), the sites demonstrated a progressive decline in precipitation and a general increase in maximum air temperature and atmospheric saturation deficit (D-max) during the mid-summer. The average (+/- SD) WUE at the grassland site was 2.6 +/- 0.7 mmol mol(-1), which was much lower than the average values observed for the two other sites (aspen: 5.4 +/- 2.3, Douglas-fir: 8.1 +/- 2.4). The differences in WUE among sites were primarily because of variation in ET. The highest maximum ET rates were approximately 5, 3.2 and 2.7 mm day(-1) for the grassland, aspen and Douglas-fir sites, respectively. There was a strong negative correlation between WUE and D-max for all sites. We also made seasonal measurements of the carbon isotope ratio of ecosystem respired CO2 (delta(R)) in order to test for the expected correlation between shifts in environmental conditions and changes to the ecosystem-integrated ratio of leaf intercellular to ambient CO2 concentration (c(i)/c(a)). There was a consistent increase in delta(R) values in the grassland, aspen forest and Douglas-fir forest associated with a seasonal reduction in soil moisture. Comparisons were made between WUE measured using eddy covariance with that calculated based on D and delta(R) measurements. There was excellent agreement between WUE values calculated using the two techniques. Our delta(R) measurements indicated that c(i)/c(a) values were quite similar among the Douglas-fir, aspen and grassland sites, despite large variation in environmental conditions among sites. This implied that the shorter-lived grass species had relatively high c(i)/c(a) values for the D of their habitat. By contrast, the longer-lived Douglas-fir trees were more conservative in water-use with lower c(i)/c(a) values relative to their habitat D. This illustrates the interaction between biological and environmental characteristics influencing ecosystem-level WUE. The strong correlation we observed between the two independent measurements of WUE, indicates that the stable isotope composition of respired CO2 is a useful ecosystem-scale tool to help study constraints to photosynthesis and acclimation of ecosystems to environmental stress. |
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Univ Lethbridge, Dept Biol Sci, Lethbridge, AB T1K 3M4, Canada, Email: larry.flanagan@uleth.ca |
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BLACKWELL PUBLISHING |
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1354-1013 |
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ISI:000234974900013 |
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EcoFoG @ eric.marcon @ |
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226 |
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Eva, H.D.; Belward, A.S.; De Miranda, E.E.; Di Bella, C.M.; Gond, V.; Huber, O.; Jones, S.; Sgrenzaroli, M.; Fritz, S. |
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Title |
A land cover map of South America |
Type |
Journal Article |
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Year |
2004 |
Publication |
Global Change Biology |
Abbreviated Journal |
Glob. Change Biol. |
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Volume |
10 |
Issue |
5 |
Pages |
731-744 |
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Keywords |
Amazonia; ecosystems; land cover; mapping; South America; vegetation classes |
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A digital land cover map of South America has been produced using remotely sensed satellite data acquired between 1995 and the year 2000. The mapping scale is defined by the 1 km spatial resolution of the map grid-cell. In order to realize the product, different sources of satellite data were used, each source providing either a particular parameter of land cover characteristic required by the legend, or mapping a particular land cover class. The map legend is designed both to fit requirements for regional climate modelling and for studies on land cover change. The legend is also compatible with a wider, global, land cover mapping exercise, which seeks to characterize the world's land surface for the year 2000. As a first step, the humid forest domain has been validated using a sample of high-resolution satellite images. The map demonstrates both the major incursions of agriculture into the remaining forest domains and the extensive areas of agriculture, which now dominate South America's grasslands. |
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Commiss European Communities, Joint Res Ctr, Inst Environm & Sustainabil, TP 440, I-21020 Ispra, Italy, Email: hugh.eva@jrc.it |
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BLACKWELL PUBLISHING LTD |
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1354-1013 |
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ISI:000221421600015 |
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EcoFoG @ eric.marcon @ |
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235 |
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Baraloto, C.; Rabaud, S.; Molto, Q.; Blanc, L.; Fortunel, C.; Herault, B.; Davila, N.; Mesones, I.; Rios, M.; Valderrama, E.; Fine, P.V.A. |
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Disentangling stand and environmental correlates of aboveground biomass in Amazonian forests |
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2011 |
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Global Change Biology |
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Glob. Change Biol. |
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17 |
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8 |
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2677-2688 |
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carbon stocks; climate; flooded forest; forest structure; French Guiana; Peru; REDD; soil properties; tropical rainforest; white-sand forest; wood specific gravity |
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Tropical forests contain an important proportion of the carbon stored in terrestrial vegetation, but estimated aboveground biomass (AGB) in tropical forests varies two-fold, with little consensus on the relative importance of climate, soil and forest structure in explaining spatial patterns. Here, we present analyses from a plot network designed to examine differences among contrasting forest habitats (terra firme, seasonally flooded, and white-sand forests) that span the gradient of climate and soil conditions of the Amazon basin. We installed 0.5-ha plots in 74 sites representing the three lowland forest habitats in both Loreto, Peru and French Guiana, and we integrated data describing climate, soil physical and chemical characteristics and stand variables, including local measures of wood specific gravity (WSG). We use a hierarchical model to separate the contributions of stand variables from climate and soil variables in explaining spatial variation in AGB. AGB differed among both habitats and regions, varying from 78 Mg ha(-1) in white-sand forest in Peru to 605 Mg ha(-1) in terra firme clay forest of French Guiana. Stand variables including tree size and basal area, and to a lesser extent WSG, were strong predictors of spatial variation in AGB. In contrast, soil and climate variables explained little overall variation in AGB, though they did co-vary to a limited extent with stand parameters that explained AGB. Our results suggest that positive feedbacks in forest structure and turnover control AGB in Amazonian forests, with richer soils (Peruvian terra firme and all seasonally flooded habitats) supporting smaller trees with lower wood density and moderate soils (French Guianan terra firme) supporting many larger trees with high wood density. The weak direct relationships we observed between soil and climate variables and AGB suggest that the most appropriate approaches to landscape scale modeling of AGB in the Amazon would be based on remote sensing methods to map stand structure. |
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[Baraloto, Christopher; Rabaud, Suzanne; Fortunel, Claire; Rios, Marcos; Valderrama, Elvis] INRA, UMR Ecol Forets Guyane, Kourou 97387, French Guiana, Email: chris.baraloto@ecofog.gf |
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Wiley-Blackwell |
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1354-1013 |
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ISI:000292308300013 |
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EcoFoG @ webmaster @ |
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325 |
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Rowland, L.; Hill, T.C.; Stahl, C.; Siebicke, L.; Burban, B.; Zaragoza-Castells, J.; Ponton, S.; Bonal, D.; Meir, P.; Williams, M. |
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Evidence for strong seasonality in the carbon storage and carbon use efficiency of an Amazonian forest |
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2014 |
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Global Change Biology |
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Global Change Biol. |
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20 |
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3 |
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979-991 |
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Carbon use efficiency; Dalec; Data assimilation; Ecosystem respiration; French Guiana; Seasonal carbon fluxes; Tropical forest |
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The relative contribution of gross primary production and ecosystem respiration to seasonal changes in the net carbon flux of tropical forests remains poorly quantified by both modelling and field studies. We use data assimilation to combine nine ecological time series from an eastern Amazonian forest, with mass balance constraints from an ecosystem carbon cycle model. The resulting analysis quantifies, with uncertainty estimates, the seasonal changes in the net carbon flux of a tropical rainforest which experiences a pronounced dry season. We show that the carbon accumulation in this forest was four times greater in the dry season than in the wet season and that this was accompanied by a 5% increase in the carbon use efficiency. This seasonal response was caused by a dry season increase in gross primary productivity, in response to radiation and a similar magnitude decrease in heterotrophic respiration, in response to drying soils. The analysis also predicts increased carbon allocation to leaves and wood in the wet season, and greater allocation to fine roots in the dry season. This study demonstrates implementation of seasonal variations in parameters better enables models to simulate observed patterns in data. In particular, we highlight the necessity to simulate the seasonal patterns of heterotrophic respiration to accurately simulate the net carbon flux seasonal tropical forest. © 2013 The Authors Global Change Biology Published by John Wiley & Sons Ltd. |
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Research School of Biology, Division of Plant Sciences, Australian National University, Canberra, ACT, 0200, Australia |
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13541013 (Issn) |
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Cited By (since 1996):1; Export Date: 24 February 2014; Source: Scopus; Language of Original Document: English; Correspondence Address: Rowland, L.; School of Geosciences, University of Edinburgh, Edinburgh, EH9 3JN, United Kingdom; email: lucy.rowland@ed.ac.uk; Funding Details: FT110100457, ARC, Australian Research Council; Funding Details: NE/F002149/1, NERC, Natural Environment Research Council; Funding Details: NE/J011002/1, NERC, Natural Environment Research Council |
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