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Chapter Six - Floristic shifts versus critical transitions in Amazonian forest systems
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- By Jérôme Chave, Université Paul Sabatier
- Edited by David A. Coomes, University of Cambridge, David F. R. P. Burslem, University of Aberdeen, William D. Simonson, University of Cambridge
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- Book:
- Forests and Global Change
- Published online:
- 05 June 2014
- Print publication:
- 20 February 2014, pp 131-160
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Summary
Introduction
Tropical forests hold close to 250 Pg of carbon, with Latin America contributing half of this (Saatchi et al. 2011). Although the rates of deforestation appear to have decreased over the past decade, tropical deforestation still represents the bulk of the c. 1.1 PgC yr−1 of C emissions due to land-use change (Friedlingstein et al. 2010). The direct impact of deforestation and degradation has the potential to be mitigated through a performance-based mechanism such as REDD (Reducing Emissions from Deforestation and Forest Degradation), by monetising carbon held in both managed and unmanaged forests (Agrawal, Nepstad & Chhatre 2011). Additionally, tropical forests contribute to a terrestrial carbon sink (Le Quéré et al. 2009), offsetting fossil carbon emissions into the atmosphere through a physiological response of the vegetation (Lewis et al. 2009; Lloyd & Farquhar 2008). Thus tropical forests offer critically important ecosystem services by reducing the short-term effect of anthropogenic carbon emissions into the atmosphere.
However, in the face of global climate trends, the resilience of tropical forests has been called into question (Cox et al. 2000). South America is sensitive to a number of large-scale climatic anomalies, including the El Niño Southern Oscillation, the Pacific Decadal Oscillation and the North Atlantic Oscillation. All of these contribute to displacing the yearly course of the Inter-Tropical Convergence Zone (ITCZ) and increase the strength of the dry season in some regions (Garreaud et al. 2009; Marengo 2004). The 2005 and the 2010 climatic events over Amazonia have exemplified these atmospheric regime shifts, and these may occur more frequently during the twenty-first century. As a result of the increased likelihood of severe droughts, models suggest that Amazonian forests may shift by 2100 to a different biome type akin to a woodland savanna or dry forest (Cox et al. 2000, 2004; Huntingford et al. 2008; Malhi et al. 2009; Poulter et al. 2010). Aside from the radical implications for human and wildlife populations inhabiting Amazonia, this new biome type would have far less potential to hold carbon, and such a shift would have important consequences for global life support services. Some of the predictions of this ‘Amazon dieback’ scenario have been empirically tested (Phillips et al. 2009). Theoretical work has also attempted to understand whether a shift showing alternative stable states is a likely outcome.
Contributors
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- By Pierre Amarenco, Adrià Arboix, Marcel Arnold, Robert W. Baloh, John Bamford, Jason J. S. Barton, Claudio L. Bassetti, Christopher F. Bladin, Julien Bogousslavsky, Julian Bösel, Marie-Germaine Bousser, Thomas Brandt, John C. M. Brust, Erica C. S. Camargo, Louis R. Caplan, Emmanuel Carrera, Carlo W. Cereda, Seemant Chaturvedi, Claudia Chaves, Chin-Sang Chung, Isabelle Crassard, Hans Christoph Diener, Marianne Dieterich, Ralf Dittrich, Geoffrey A. Donnan, Paul Eslinger, Conrado J. Estol, Edward Feldmann, José M. Ferro, Joseph Ghika, Daniel Hanley, Ahamad Hassan, Cathy Helgason, Argye E. Hillis, Marc Hommel, Carlos S. Kase, Julia Kejda-Scharler, Jong S. Kim, Rainer Kollmar, Joshua Kornbluth, Sandeep Kumar, Emre Kumral, Hyung Lee, Didier Leys, Eric Logigian, Mauro Manconi, Elisabeth B. Marsh, Randolph S. Marshall, Isabel P. Martins, Josep Lluís Martí-Vilalta, Heinrich P. Mattle, Jérome Mawet, Mikael Mazighi, Patrik Michel, Jay Preston Mohr, Thierry Moulin, Sandra Narayanan, Kwang-Yeol Park, Florence Pasquier, Charles Pierrot-Deseilligny, Nils Petersen, Raymond Reichwein, E. Bernd Ringelstein, Gabriel J. E. Rinkel, Elliott D. Ross, Arnaud Saj, Martin A. Samuels, Jeremy D. Schmahmann, Stefan Schwab, Florian Stögbauer, Mathias Sturzenegger, Laurent Tatu, Pariwat Thaisetthawatkul, Dagmar Timmann, Jan van Gijn, Ana Verdelho, Francois Vingerhoets, Patrik Vuilleumier, Fabrice Vuillier, Eelco F. M. Wijdicks, Shirley H. Wray, Wendy C. Ziai
- Edited by Louis R. Caplan, Jan van Gijn
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- Book:
- Stroke Syndromes, 3ed
- Published online:
- 05 August 2012
- Print publication:
- 12 July 2012, pp vii-x
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Above-ground biomass and productivity in a rain forest of eastern South America
- Jérôme Chave, Jean Olivier, Frans Bongers, Patrick Châtelet, Pierre-Michel Forget, Peter van der Meer, Natalia Norden, Bernard Riéra, Pierre Charles-Dominique
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- Journal:
- Journal of Tropical Ecology / Volume 24 / Issue 4 / July 2008
- Published online by Cambridge University Press:
- 01 July 2008, pp. 355-366
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The dynamics of tropical forest woody plants was studied at the Nouragues Field Station, central French Guiana. Stem density, basal area, above-ground biomass and above-ground net primary productivity, including the contribution of litterfall, were estimated from two large permanent census plots of 12 and 10 ha, established on contrasting soil types, and censused twice, first in 1992–1994, then again in 2000–2002. Mean stem density was 512 stems ha−1 and basal area, 30 m2 ha−1. Stem mortality rate ranged between 1.51% and 2.06% y−1. In both plots, stem density decreased over the study period. Using a correlation between wood density and wood hardness directly measured by a Pilodyn wood tester, we found that the mean wood density was 0.63 g cm−3, 12% smaller than the mean of wood density estimated from the literature values for the species occurring in our plot. Above-ground biomass ranged from 356 to 398 Mg ha−1 (oven-dry mass), and it increased over the census period. Leaf biomass was 6.47 Mg ha−1. Our total estimate of aboveground net primary productivity was 8.81 MgC ha−1 y−1 (in carbon units), not accounting for loss to herbivory, branchfalls, or biogenic volatile organic compounds, which may altogether account for an additional 1 MgC ha−1 y−1. Coarse wood productivity (stem growth plus recruitment) contributed to 4.16 MgC ha−1 y−1. Litterfall contributed to 4.65 MgC ha−1 y−1 with 3.16 MgC ha−1 y−1 due to leaves, 1.10 MgC ha−1 y−1 to twigs, and 0.39 MgC ha−1 y−1 to fruits and flowers. The increase in above-ground biomass for both trees and lianas is consistent with the hypothesis of a shift in the functioning of Amazonian rain forests driven by environmental changes, although alternative hypotheses such as a recovery from past disturbances cannot be ruled out at our site, as suggested by the observed decrease in stem density.
8 - The importance of phylogenetic structure in biodiversity studies
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- By Jérôme Chave, Université Paul Sabatier, Toulouse, Guillem Chust, Université Paul Sabatier, Toulouse, Christophe Thébaud, Université Paul Sabatier, Toulouse
- Edited by David Storch, Charles University, Prague, Pablo Marquet, Pontificia Universidad Catolica de Chile, James Brown, University of New Mexico
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- Book:
- Scaling Biodiversity
- Published online:
- 05 August 2012
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- 12 July 2007, pp 150-167
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Summary
Introduction
A central goal of biodiversity research is to understand processes of species coexistence at different spatial and temporal scales. Much empirical research has revolved around documenting patterns of species abundance and distribution with sound sampling techniques and statistics (May, 1975; Magurran, 1988; Krebs, 1998). Such data are of tremendous importance not only for documenting current biological diversity patterns, but also for testing fundamental ecological theories (Ricklefs & Schluter, 1993; Brown, 1995; Hubbell, 2001). A common feature of these approaches is the emphasis placed on species as the appropriate currency for quantifying biological diversity. However, documenting species diversity often represents a considerable practical challenge. First, no one exactly knows the total number of extant species on Earth (Erwin, 1982; May, 1994; Novotný et al., 2002; Alroy, 2002). Second, in any given sample, a sizeable fraction of the individuals may represent previously undescribed species, as is especially the case for lesser known groups, like plants in tropical forests, insects or protists. Third, species recognition usually relies upon a set of morphological cues which are not always observable. Thus, many individuals within a sample cannot be reliably assigned to previously described species. This is obvious in microbial communities, where different operational taxonomic units (OTUs) can only be distinguished by DNA screening or other molecular methods (e.g. see Suau et al., 1999 for a study of the microbial diversity of the human gut, and Green & Bohannan, this volume). This issue is also serious in macroscopic organisms.
Fast determination of light availability and leaf area index in tropical forests
- Laurent Cournac, Marc-Antoine Dubois, Jérôme Chave, Bernard Riéra
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- Journal:
- Journal of Tropical Ecology / Volume 18 / Issue 2 / March 2002
- Published online by Cambridge University Press:
- 06 March 2002, pp. 295-302
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An important property of plant communities is the Leaf Area Index (LAI), which is the vertically integrated surface of leaves per unit of ground area. Leaves are the primary sites of photosynthesis and transpiration, thus the LAI, which conditions the light interception by the canopy, is directly related to carbon and water exchange with the atmosphere at the stand scale (McNaughton & Jarvis 1983). LAI also has an impact on tree growth through the interception of light. Light availability below canopies is the principal limiting factor of tree recruitment and growth in forests (Denslow et al. 1990). Several methodologies have been used for measuring LAI in the field. These can be classiffed in four categories (Marshall & Waring 1986): (1) direct measurements by litterfall collection or destructive sampling, (2) allometric correlations with variables such as tree height or tree diameter, (3) gap-fraction assessment (e.g. with hemispherical photographs), (4) measurement of light transmittance with optical sensors.
Estimation of biomass in a neotropical forest of French Guiana: spatial and temporal variability
- JÉRÔME CHAVE, BERNARD RIÉRA, MARC-A. DUBOIS
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- Journal:
- Journal of Tropical Ecology / Volume 17 / Issue 1 / January 2001
- Published online by Cambridge University Press:
- 08 February 2001, pp. 79-96
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Biomass content and turnover rate were estimated for a lowland wet rain forest in French Guiana. A regression model relating the biomass of a tree to its dbh (diameter at breast height) was deduced from previously published data. A power-law allometric relationship of the form AGTB = aDb was used to estimate the tree biomass, AGTB (Mg ha−1), from its dbh D (cm). Using direct measurements of tree biomass in the literature, the best-fit allometric exponent b = 2.42 (SD = 0.02) was found. The logarithm of the coefficient a was normally distributed with an average of −2.00 (SD = 0.27). This method was applied to two permanent research stations of the lowland tropical rain forest of French Guiana: the Nouragues and Piste de Saint-Elie. At the Nouragues, the biomass was estimated from trees 10 cm in diameter on two plots covering a total surface area of 22 ha and yielded an average biomass of 309 Mg ha−1 (± 32 Mg ha−1, 95% confidence interval). Spatial variability was also addressed at the Nouragues by estimating the biomass of trees ≥ 30 cm dbh over a total surface area of 82 ha. For the wet tropical forest vegetation type, an average of 284 Mg ha−1 was obtained (spatial variability ±55 Mg ha−1). Biomass turnover was evaluated at Piste de Saint-Elie from two transects (0.78 and 1 ha) on which all trees ≥5 cm in diameter were recorded and mapped twice in 10 y. Transect 1 showed a slight increase in biomass, from 245 to 260 Mg ha−1 (338 to 345 Mg ha−1 for transect 2), corresponding to a net increase of 1.9 Mg ha−1 y−1 (0.7 Mg ha−1 y−1), and the biomass ingrowth was 3.2 Mg ha−1 y−1 (2.8 Mg ha−1 y−1). These figures are discussed in the light of the natural recruitment dynamics of tropical forests.