Showing papers by "Oliver L. Phillips published in 2013"
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Utrecht University1, Naturalis2, Duke University3, Institut de recherche pour le développement4, Institut national de la recherche agronomique5, Museu Paraense Emílio Goeldi6, University of California, Berkeley7, University of Leeds8, Empresa Brasileira de Pesquisa Agropecuária9, National Institute of Amazonian Research10, National University of Saint Anthony the Abbot in Cuzco11, University of Exeter12, World Wide Fund for Nature13, Universidad Autónoma Gabriel René Moreno14, Norwegian University of Life Sciences15, Max Planck Society16, James Cook University17, Universidade do Estado de Mato Grosso18, University of Amsterdam19, Silver Spring Networks20, State University of Campinas21, University of Edinburgh22, University of Los Andes23, Smithsonian Conservation Biology Institute24, National University of Colombia25, University of East Anglia26, Central University of Ecuador27, Centre national de la recherche scientifique28, Humboldt State University29, New York Botanical Garden30, Universidade Federal do Acre31, Paul Sabatier University32, Missouri Botanical Garden33, Amazon.com34, University of Texas at Austin35, University of Florida36, Venezuelan Institute for Scientific Research37, Environmental Change Institute38, Federal Rural University of Amazonia39, University of São Paulo40, State University of Norte Fluminense41, Smithsonian Tropical Research Institute42, University of Wisconsin–Milwaukee43, Northern Arizona University44, Aarhus University45, Tropenbos International46, University of Kent47, Royal Botanic Gardens48, Universidad Nacional de la Amazonía Peruana49, University of Missouri–St. Louis50, Fairchild Tropical Botanic Garden51, Florida International University52, Wake Forest University53
TL;DR: The finding that Amazonia is dominated by just 227 tree species implies that most biogeochemical cycling in the world’s largest tropical forest is performed by a tiny sliver of its diversity.
Abstract: The vast extent of the Amazon Basin has historically restricted the study of its tree communities to the local and regional scales. Here, we provide empirical data on the commonness, rarity, and richness of lowland tree species across the entire Amazon Basin and Guiana Shield (Amazonia), collected in 1170 tree plots in all major forest types. Extrapolations suggest that Amazonia harbors roughly 16,000 tree species, of which just 227 (1.4%) account for half of all trees. Most of these are habitat specialists and only dominant in one or two regions of the basin. We discuss some implications of the finding that a small group of species—less diverse than the North American tree flora—accounts for half of the world’s most diverse tree community.
963 citations
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TL;DR: In this paper, the authors review the environmental factors controlling the structure and distribution of forests and evaluate their current and future trajectory, concluding that forest biomass is a complex property affected by forest distribution, structure, and ecological processes.
Abstract: Forests are the dominant terrestrial ecosystem on Earth. We review the environmental factors controlling their structure and global distribution and evaluate their current and future trajectory. Adaptations of trees to climate and resource gradients, coupled with disturbances and forest dynamics, create complex geographical patterns in forest assemblages and structures. These patterns are increasingly discernible through new satellite and airborne observation systems, improved forest inventories, and global ecosystem models. Forest biomass is a complex property affected by forest distribution, structure, and ecological processes. Since at least 1990, biomass density has consistently increased in global established forests, despite increasing mortality in some regions, suggesting that a global driver such as elevated CO2 may be enhancing biomass gains. Global forests have also apparently become more dynamic. Advanced information about the structure, distribution, and biomass of the world's forests provides...
621 citations
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Environmental Change Institute1, University of Leeds2, University of Exeter3, National Center for Atmospheric Research4, University of Sheffield5, Met Office6, University College London7, Australian National University8, James Cook University9, University of Edinburgh10, National Institute for Space Research11
TL;DR: In this paper, an exploration of results from 22 climate models in conjunction with a land surface scheme suggests that the resilience of tropical forests to climate change is higher than expected, although uncertainties are large.
Abstract: Assessing potential future carbon loss from tropical forests is important for evaluating the efficacy of programmes for reducing emissions from deforestation and degradation (REDD). An exploration of results from 22 climate models in conjunction with a land surface scheme suggests that in the Americas, Africa and Asia, the resilience of tropical forests to climate change is higher than expected, although uncertainties are large.
379 citations
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University College London1, University of Leeds2, University of Yaoundé I3, Center for International Forestry Research4, Smithsonian Tropical Research Institute5, University of Wisconsin–Milwaukee6, Forestry Commission7, University of Liège8, École Normale Supérieure9, Université libre de Bruxelles10, Royal Museum for Central Africa11, Ghent University12, Duke University13, London School of Economics and Political Science14, Forestry Research Institute of Ghana15, Wildlife Conservation Society16, Royal Botanic Garden Edinburgh17, American Museum of Natural History18, Austral University of Chile19, University of Stirling20, James Cook University21, University of Oxford22, University of York23, University of Agriculture, Faisalabad24, University of Cambridge25, Southern Cross University26, National University of Singapore27, University of Toronto28, University of Southampton29
TL;DR: The results indicate that AGB is mediated by both climate and soils, and suggest that the AGB of African closed-canopy tropical forests may be particularly sensitive to future precipitation and temperature changes.
Abstract: We report above-ground biomass (AGB), basal area, stem density and wood mass density estimates from 260 sample plots (mean size: 1.2 ha) in intact closed-canopy tropical forests across 12 African countries. Mean AGB is 395.7 Mg dry mass ha−1 (95% CI: 14.3), substantially higher than Amazonian values, with the Congo Basin and contiguous forest region attaining AGB values (429 Mg ha−1) similar to those of Bornean forests, and significantly greater than East or West African forests. AGB therefore appears generally higher in palaeo- compared with neotropical forests. However, mean stem density is low (426 ± 11 stems ha−1 greater than or equal to 100 mm diameter) compared with both Amazonian and Bornean forests (cf. approx. 600) and is the signature structural feature of African tropical forests. While spatial autocorrelation complicates analyses, AGB shows a positive relationship with rainfall in the driest nine months of the year, and an opposite association with the wettest three months of the year; a negative relationship with temperature; positive relationship with clay-rich soils; and negative relationships with C : N ratio (suggesting a positive soil phosphorus–AGB relationship), and soil fertility computed as the sum of base cations. The results indicate that AGB is mediated by both climate and soils, and suggest that the AGB of African closed-canopy tropical forests may be particularly sensitive to future precipitation and temperature changes.
302 citations
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TL;DR: In this paper, the authors report that the catchment of the world's largest river is experiencing a substantial wetting trend since approximately 1990, which coincides with the onset of an upward trend in tropical Atlantic sea surface temperatures (SST).
Abstract: The Amazon basin hosts half the planet's remaining moist tropical forests, but they may be threatened in a warming world. Nevertheless, climate model predictions vary from rapid drying to modest wetting. Here we report that the catchment of the world's largest river is experiencing a substantial wetting trend since approximately 1990. This intensification of the hydrological cycle is concentrated overwhelmingly in the wet season driving progressively greater differences in Amazon peak and minimum flows. The onset of the trend coincides with the onset of an upward trend in tropical Atlantic sea surface temperatures (SST). This positive longer-term correlation contrasts with the short-term, negative response of basin-wide precipitation to positive anomalies in tropical North Atlantic SST, which are driven by temporary shifts in the intertropical convergence zone position. We propose that the Amazon precipitation changes since 1990 are instead related to increasing atmospheric water vapor import from the warming tropical Atlantic.
278 citations
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TL;DR: Tracking and predicting the effects of environmental change on tree biomass requires well-designed studies that address the issues that are reviewed, and statistical control of the axiomatic co-variation of tree size and age is required.
220 citations
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TL;DR: It was found that stem height was the best predictor variable for arborescent palm biomass, but the relationship between stem height and biomass differed among species, and most species showed weak biomass–diameter relationships, but a significant relationship could be identified across all species.
120 citations
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TL;DR: In this article, the woody biomass residence time (τw) of an ecosystem is an important variable for accurately simulating its biomass stocks, and the authors reviewed published data from 177 ecosystems.
Abstract: Background: The woody biomass residence time (τw) of an ecosystem is an important variable for accurately simulating its biomass stocks. Methods and results: We reviewed published data from 177 for...
117 citations
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James Cook University1, University of Leeds2, University of Edinburgh3, Forest Research Institute4, Commonwealth Scientific and Industrial Research Organisation5, Universidade do Estado de Mato Grosso6, Royal Botanic Garden Edinburgh7, University of Yaoundé I8, National Institute of Amazonian Research9, University of Brasília10, Forestry Commission11, University of Tasmania12, Conservation International13, University College London14
TL;DR: In this article, the authors integrated observed variations in tropical vegetation structure and floristic composition into a single classification scheme by using clustering techniques to identify twelve structural groupings based on height and canopy cover of the dominant upper stratum.
Abstract: Background: There is no generally agreed classification scheme for the many different vegetation formation types occurring in the tropics. This hinders cross-continental comparisons and causes confusion as words such as ‘forest’ and ‘savanna’ have different meanings to different people. Tropical vegetation formations are therefore usually imprecisely and/or ambiguously defined in modelling, remote sensing and ecological studies. Aims: To integrate observed variations in tropical vegetation structure and floristic composition into a single classification scheme. Methods: Using structural and floristic measurements made on three continents, discrete tropical vegetation groupings were defined on the basis of overstorey and understorey structure and species compositions by using clustering techniques. Results: Twelve structural groupings were identified based on height and canopy cover of the dominant upper stratum and the extent of lower-strata woody shrub cover and grass cover. Structural classifications di...
110 citations
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TL;DR: Overall, current evidence indicates that the increase in lianas will negatively impact the carbon balance of tropical forests, with potentially far-reaching consequences for global atmospheric CO2 levels and associated climate change.
Abstract: Mature tropical forests sequester large quantities of atmospheric CO2, which they store as plant biomass. These forests are changing however, including an increase in liana abundance and biomass over recent decades in Neotropical forests. We ask here how this increase in lianas might impact the tropical forest carbon cycle and their capacity for carbon storage and sequestration. Lianas reduce tree growth, survival, and leaf productivity; however, lianas also invest significantly in leaf production, and the increase in lianas could conceivably offset liana-induced reductions in tree canopy productivity with no adverse effects to the forest-level canopy productivity. By contrast, lianas decrease the total ecosystem uptake of carbon by reducing tree biomass productivity. Lianas themselves invest little in woody biomass, and store and sequester only a small proportion of the biomass in tropical forests. As lianas increase they may effectively displace trees, but the greater liana carbon stocks are unlikely to compensate for liana-induced losses in net carbon sequestration and storage by trees. A potentially important additional consideration is the impact of lianas on the tree community. By competing more intensely with shade-tolerant, more densely wooded trees than with fast-growing, light-wooded trees, lianas may shift tree composition toward faster-growing species, which store relatively little carbon, and thereby further reduce the carbon storage capacity of tropical forests. Overall, current evidence indicates that the increase in lianas will negatively impact the carbon balance of tropical forests, with potentially far-reaching consequences for global atmospheric CO2 levels and associated climate change.
Resumen
Los bosques tropicales maduros secuestran grandes cantidades de CO2 atmosferico, el cual se almacena en forma de biomasa vegetal. Estos bosques estan cambiando; el numero de lianas y su biomasa, incluyendo el aumentado en abundancia y biomasa de las lianas en las ultimas decadas en los bosques neotropicales. Nos preguntamos entonces como el aumento de las lianas podria afectar el ciclo del carbono de los bosques tropicales y su capacidad para secuestrar y almacenar carbono. Las lianas reducen el crecimiento de los arboles, disminuyen su supervivencia y productividad foliar; sin embargo, las lianas tambien invierten de manera significativa en la produccion de hojas, por lo que el aumento de las lianas podria posiblemente compensar la reduccion inducida por estas en la productividad del dosel arboreo sin efectos adversos en la productividad a nivel del dosel forestal. Por el contrario, las lianas disminuyen la absorcion total de carbono de los ecosistemas mediante la reduccion en la produccion de biomasa de los arboles. Las lianas invierten poco en biomasa lenosa y almacenan y secuestran solo una pequena proporcion de biomasa en los bosques tropicales. A medida que las lianas aumentan en los bosques tropicales, estas podrian desplazar a los arboles y es poco probable que poblaciones mas abundantes de lianas compensen las perdidas inducidas por si mismas en el secuestro neto de carbono y almacenamiento de los arboles. Una consideracion adicional potencialmente importante es el impacto de las lianas en la comunidad de arboles. Al competir mas intensamente con arboles que toleran la sombra, y con madera mas densa, respecto a arboles de crecimiento rapido y con madera menos densa, las lianas pueden modificar la composicion de las especies de arboles favoreciendo a especies de crecimiento mas rapido, que almacenan relativamente menos carbono, y por lo tanto, se reduce aun mas la capacidad de almacenamiento de carbono de los bosques tropicales. En general, las ultimas evidencias indican que el aumento de las lianas tendra un impacto negativo en el balance de carbono de los bosques tropicales con consecuencias de gran alcance para los niveles globales de CO2 en la atmosfera y el cambio climatico asociado.
105 citations
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TL;DR: In this paper, the authors examined the evidence for concerted changes in the structure, dynamics, and functional composition of old-growth Amazonian forests over recent decades and estimated a net biomass increase in trees > 10 cm diameter of 0.62 ± 0.23 t C ha -1 a -1 through the late twentieth century.
Abstract: © 2009 by the American Geophysical Union. All rights reserved. Long-term, on-the-ground monitoring of forest plots distributed across Amazonia provides a powerful means to quantify stocks and fluxes of biomass and biodiversity. Here we examine the evidence for concerted changes in the structure, dynamics, and functional composition of old-growth Amazonian forests over recent decades. Mature forests have, as a whole, gained biomass and undergone accelerated growth and dynamics, but questions remain as to the long-term persistence of these changes. Because forest growth on average exceeds mortality, intact Amazonian forests have been functioning as a carbon sink. We estimate a net biomass increase in trees > 10 cm diameter of 0.62 ± 0.23 t C ha -1 a -1 through the late twentieth century. If representative of the wider forest landscape, this translates into a sink in South American old-growth forest of at least 0.49 ± 0.18 Pg C a -1 . If other biomass and necromass components also increased proportionally, the estimated South American old-growth forest sink is 0.79 ± 0.29 Pg C a -1 , before allowing for possible gains in soil carbon. If tropical forests elsewhere are behaving similarly, the old-growth biomass forest sink would be 1.60 ± 0.58 Pg C a -1 . This bottom-up estimate of the carbon balance of tropical forests is preliminary, pending syntheses of detailed biometric studies across the other tropical continents. There is also some evidence for recent changes in the functional composition (biodiversity) of Amazonian forest, but the evidence is less comprehensive than that for changes in structure and dynamics. The most likely driver(s) of changes are recent increases in the supply of resources such as atmospheric carbon dioxide, which would increase net primary productivity, increasing tree growth and recruitment, and, in turn, mortality. In the future the growth response of remaining undisturbed Amazonian forests is likely to saturate, and there is a risk of these ecosystems transitioning from sink to source driven by higher respiration (temperature), higher mortality (drought), or compositional change (functional shifts toward lighterwooded plants). Even a modest switch from carbon sink to source for Amazonian forests would impact global climate, biodiversity, and human welfare, while the documented acceleration of tree growth and mortality may already be affecting the interactions of thousands of plant and millions of animal species.
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TL;DR: This paper provided empirical data on the commonness, rarity, and richness of lowland tree species across the entire Amazon Basin and Guiana Shield (Amazonia), collected in 1170 tree plots in all major forest types.
Abstract: The vast extent of the Amazon Basin has historically restricted the study of its tree communities to the local and regional scales. Here, we provide empirical data on the commonness, rarity, and richness of lowland tree species across the entire Amazon Basin and Guiana Shield (Amazonia), collected in 1170 tree plots in all major forest types. Extrapolations suggest that Amazonia harbors roughly 16,000 tree species, of which just 227 (1.4%) account for half of all trees. Most of these are habitat specialists and only dominant in one or two regions of the basin. We discuss some implications of the finding that a small group of species—less diverse than the North American tree flora—accounts for half of the world’s most diverse tree community.
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TL;DR: In this paper, the authors argue that the disclosure of an enterprise's financial condition and the concomitant determination of its capital adequacy must be a function of accounting rather than financial modeling, and they further argue that if accounting is to fulfill this core function, the current practice of basing accounting on fair values must be adapted such that accounting is based on the risk exposures inherent in approved transactions.
Abstract: The resetting of the risk management agenda through successive capital accords has had little impact on the ability of many firms to prevent losses which raises concerns as to whether the risk calculation methods applied in the calibration of regulatory capital are fit for purpose. This has been the focus of recent public comment by global regulators, central bankers and industry commentators who suggest that excessively complex and flawed capital adequacy rules that rely on risk modeling techniques such as Value-at-Risk (VaR) were a contributing factor in the financial crisis. We argue that the disclosure of an enterprise’s financial condition and the concomitant determination of its capital adequacy must be a function of accounting rather than financial modeling. We further argue that if accounting is to fulfill this core function, the current practice of basing accounting on fair values must be adapted such that accounting is based on the risk exposures inherent in approved transactions. In this paper we demonstrate how this may be achieved by adding risk information to the existing management information that is attached to transactions upon their registration in accounting systems. The incremental risk information enables a calculation of risk-weighted transaction values that are accounted for using a new risk abstraction - the Risk Unit (RU). In this way a comprehensive risk management system is created that is tied to the financials of the enterprise. We further demonstrate how risk accounting aligned with management accounting can produce a system of integrated risk and management reporting by, for example, group, organisation unit, product, customer and geography which, in turn, enables the risk appetite setting process to become an integral part of the enterprise’s financial planning and budgeting cycle. Over time, risk accounting outputs can be correlated with expected and actual losses thereby imparting a monetary value to the RU abstraction which can be used in the determination of regulatory capital requirements, the computation of risk adjusted return on capital (RAROC) and adjusting the betas in the capital asset pricing model (CAPM) thus bridging accounting with economic theory and risk management concepts.
01 Dec 2013
01 Jan 2013
TL;DR: Plant δ15N indicate that low levels of nitrogen availability are only likely to influence Amazon forest function on immature or old weathered soils and/or where dry-season precipitation is low, suggesting a restricted availability of nitrogen on both young and old soils and the atmosphere.