Author
Julie Peacock
Bio: Julie Peacock is an academic researcher from University of Leeds. The author has contributed to research in topics: Amazon rainforest & Carbon sink. The author has an hindex of 19, co-authored 33 publications receiving 4666 citations.
Papers
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TL;DR: Records from multiple long-term monitoring plots across Amazonia are used to assess forest responses to the intense 2005 drought, a possible analog of future events that may accelerate climate change through carbon losses and changed surface energy balances.
Abstract: Amazon forests are a key but poorly understood component of the global carbon cycle. If, as anticipated, they dry this century, they might accelerate climate change through carbon losses and changed surface energy balances. We used records from multiple long-term monitoring plots across Amazonia to assess forest responses to the intense 2005 drought, a possible analog of future events. Affected forest lost biomass, reversing a large long-term carbon sink, with the greatest impacts observed where the dry season was unusually intense. Relative to pre-2005 conditions, forest subjected to a 100-millimeter increase in water deficit lost 5.3 megagrams of aboveground biomass of carbon per hectare. The drought had a total biomass carbon impact of 1.2 to 1.6 petagrams (1.2 × 1015 to 1.6 × 1015 grams). Amazon forests therefore appear vulnerable to increasing moisture stress, with the potential for large carbon losses to exert feedback on climate change.
1,545 citations
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University of Leeds1, University of Yaoundé I2, Forestry Commission3, University of Agriculture, Faisalabad4, Smithsonian Institution5, Mbarara University of Science and Technology6, Wageningen University and Research Centre7, Salisbury University8, Wildlife Conservation Society9, University of York10, Environmental Change Institute11, University of Dar es Salaam12, University of Aberdeen13, University College Dublin14, University of Toronto15
TL;DR: Taxon-specific analyses of African inventory and other data suggest that widespread changes in resource availability, such as increasing atmospheric carbon dioxide concentrations, may be the cause of the increase in carbon stocks, as some theory and models predict.
Abstract: The response of terrestrial vegetation to a globally changing environment is central to predictions of future levels of atmospheric carbon dioxide. The role of tropical forests is critical because they are carbon-dense and highly productive. Inventory plots across Amazonia show that old-growth forests have increased in carbon storage over recent decades, but the response of one-third of the world's tropical forests in Africa is largely unknown owing to an absence of spatially extensive observation networks. Here we report data from a ten-country network of long-term monitoring plots in African tropical forests. We find that across 79 plots (163 ha) above-ground carbon storage in live trees increased by 0.63 Mg C ha(-1) yr(-1) between 1968 and 2007 (95% confidence interval (CI), 0.22-0.94; mean interval, 1987-96). Extrapolation to unmeasured forest components (live roots, small trees, necromass) and scaling to the continent implies a total increase in carbon storage in African tropical forest trees of 0.34 Pg C yr(-1) (CI, 0.15-0.43). These reported changes in carbon storage are similar to those reported for Amazonian forests per unit area, providing evidence that increasing carbon storage in old-growth forests is a pan-tropical phenomenon. Indeed, combining all standardized inventory data from this study and from tropical America and Asia together yields a comparable figure of 0.49 Mg C ha(-1) yr(-1) (n = 156; 562 ha; CI, 0.29-0.66; mean interval, 1987-97). This indicates a carbon sink of 1.3 Pg C yr(-1) (CI, 0.8-1.6) across all tropical forests during recent decades. Taxon-specific analyses of African inventory and other data suggest that widespread changes in resource availability, such as increasing atmospheric carbon dioxide concentrations, may be the cause of the increase in carbon stocks, as some theory and models predict.
941 citations
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University of Leeds1, University of Exeter2, Imperial College London3, James Cook University4, Environmental Change Institute5, University College London6, University of Kent7, Duke University8, National Institute of Amazonian Research9, National Institute for Space Research10, Universidad Autónoma Gabriel René Moreno11, Wageningen University and Research Centre12, University of Amsterdam13, Florida International University14, Institut national de la recherche agronomique15, Universidade Federal do Acre16, Tropenbos International17, Empresa Brasileira de Pesquisa Agropecuária18, National Chung Hsing University19, Paul Sabatier University20, National Park Service21, Amazon.com22, Federal University of Pará23, Universidade do Estado de Mato Grosso24, University of Texas at Austin25, Smithsonian Institution26, World Wide Fund for Nature27, Universidad Mayor28, Field Museum of Natural History29, Universidad Nacional de la Amazonía Peruana30, University of Los Andes31, National University of Colombia32, Museu Paraense Emílio Goeldi33, Utrecht University34, Naturalis35, Northumbria University36, University of Wisconsin–Milwaukee37, Smithsonian Tropical Research Institute38, State University of Campinas39
TL;DR: It is confirmed that Amazon forests have acted as a long-term net biomass sink, but the observed decline of the Amazon sink diverges markedly from the recent increase in terrestrial carbon uptake at the global scale, and is contrary to expectations based on models
Abstract: Atmospheric carbon dioxide records indicate that the land surface has acted as a strong global carbon sink over recent decades, with a substantial fraction of this sink probably located in the tropics, particularly in the Amazon. Nevertheless, it is unclear how the terrestrial carbon sink will evolve as climate and atmospheric composition continue to change. Here we analyse the historical evolution of the biomass dynamics of the Amazon rainforest over three decades using a distributed network of 321 plots. While this analysis confirms that Amazon forests have acted as a long-term net biomass sink, we find a long-term decreasing trend of carbon accumulation. Rates of net increase in above-ground biomass declined by one-third during the past decade compared to the 1990s. This is a consequence of growth rate increases levelling off recently, while biomass mortality persistently increased throughout, leading to a shortening of carbon residence times. Potential drivers for the mortality increase include greater climate variability, and feedbacks of faster growth on mortality, resulting in shortened tree longevity. The observed decline of the Amazon sink diverges markedly from the recent increase in terrestrial carbon uptake at the global scale, and is contrary to expectations based on models.
767 citations
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University of Leeds1, National Institute of Amazonian Research2, Max Planck Society3, Venezuelan Institute for Scientific Research4, Museu Paraense Emílio Goeldi5, Karlsruhe Institute of Technology6, Smithsonian Institution7, New York University8, Indian Institute of Astrophysics9, National University of Colombia10, Conservation International11, University of Oxford12, Duke University13, University of Brasília14, Universidade Federal do Acre15, James Cook University16
TL;DR: In this paper, the authors investigated the role of soil fertility in forest structure and dynamics in the Amazon Basin in an east-west gradient coincident with variations in soil fertility and geology and found that soil fertility may play an important role in explaining Basinwide variations in forest biomass, growth and stem turnover rates.
Abstract: . Forest structure and dynamics vary across the Amazon Basin in an east-west gradient coincident with variations in soil fertility and geology. This has resulted in the hypothesis that soil fertility may play an important role in explaining Basin-wide variations in forest biomass, growth and stem turnover rates. Soil samples were collected in a total of 59 different forest plots across the Amazon Basin and analysed for exchangeable cations, carbon, nitrogen and pH, with several phosphorus fractions of likely different plant availability also quantified. Physical properties were additionally examined and an index of soil physical quality developed. Bivariate relationships of soil and climatic properties with above-ground wood productivity, stand-level tree turnover rates, above-ground wood biomass and wood density were first examined with multivariate regression models then applied. Both forms of analysis were undertaken with and without considerations regarding the underlying spatial structure of the dataset. Despite the presence of autocorrelated spatial structures complicating many analyses, forest structure and dynamics were found to be strongly and quantitatively related to edaphic as well as climatic conditions. Basin-wide differences in stand-level turnover rates are mostly influenced by soil physical properties with variations in rates of coarse wood production mostly related to soil phosphorus status. Total soil P was a better predictor of wood production rates than any of the fractionated organic- or inorganic-P pools. This suggests that it is not only the immediately available P forms, but probably the entire soil phosphorus pool that is interacting with forest growth on longer timescales. A role for soil potassium in modulating Amazon forest dynamics through its effects on stand-level wood density was also detected. Taking this into account, otherwise enigmatic variations in stand-level biomass across the Basin were then accounted for through the interacting effects of soil physical and chemical properties with climate. A hypothesis of self-maintaining forest dynamic feedback mechanisms initiated by edaphic conditions is proposed. It is further suggested that this is a major factor determining endogenous disturbance levels, species composition, and forest productivity across the Amazon Basin.
505 citations
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University of Leeds1, University of Edinburgh2, University College London3, University of Exeter4, Imperial College London5, National University of Saint Anthony the Abbot in Cuzco6, Universidad Autónoma Gabriel René Moreno7, National Institute of Amazonian Research8, Universidade do Estado de Mato Grosso9, Universidade Federal do Acre10, University of Los Andes11, University of Washington12, Environmental Change Institute13, Centre national de la recherche scientifique14, Museu Paraense Emílio Goeldi15, Lancaster University16, University of Lorraine17, Universidad Nacional de la Amazonía Peruana18, Smithsonian Institution19, University of Montpellier20, James Cook University21, Wageningen University and Research Centre22, Agro ParisTech23, Naturalis24, University of Amsterdam25, Federal University of Western Pará26, State University of Campinas27, National Institute for Space Research28, Florida International University29, University of São Paulo30, Tropenbos International31, Amazon.com32, Federal University of Pará33, Michigan Technological University34, University of Texas at Austin35, Venezuelan Institute for Scientific Research36, Polytechnic University of Valencia37, Royal Museum for Central Africa38, Tecnológico de Antioquia39, George Mason University40, Universidad del Tolima41, National University of Colombia42, Paul Sabatier University43, Georgetown University44, University of La Serena45, Forestry Commission46, Federal University of Alagoas47, Duke University48, Van Hall Larenstein University of Applied Sciences49, University of Nottingham50
TL;DR: A slow shift to a more dry‐affiliated Amazonia is underway, with changes in compositional dynamics consistent with climate‐change drivers, but yet to significantly impact whole‐community composition.
Abstract: Most of the planet's diversity is concentrated in the tropics, which includes many regions undergoing rapid climate change. Yet, while climate‐induced biodiversity changes are widely documented elsewhere, few studies have addressed this issue for lowland tropical ecosystems. Here we investigate whether the floristic and functional composition of intact lowland Amazonian forests have been changing by evaluating records from 106 long‐term inventory plots spanning 30 years. We analyse three traits that have been hypothesized to respond to different environmental drivers (increase in moisture stress and atmospheric CO2 concentrations): maximum tree size, biogeographic water‐deficit affiliation and wood density. Tree communities have become increasingly dominated by large‐statured taxa, but to date there has been no detectable change in mean wood density or water deficit affiliation at the community level, despite most forest plots having experienced an intensification of the dry season. However, among newly recruited trees, dry‐affiliated genera have become more abundant, while the mortality of wet‐affiliated genera has increased in those plots where the dry season has intensified most. Thus, a slow shift to a more dry‐affiliated Amazonia is underway, with changes in compositional dynamics (recruits and mortality) consistent with climate‐change drivers, but yet to significantly impact whole‐community composition. The Amazon observational record suggests that the increase in atmospheric CO2 is driving a shift within tree communities to large‐statured species and that climate changes to date will impact forest composition, but long generation times of tropical trees mean that biodiversity change is lagging behind climate change.
263 citations
Cited by
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28 Jul 2005
TL;DR: PfPMP1)与感染红细胞、树突状组胞以及胎盘的单个或多个受体作用,在黏附及免疫逃避中起关键的作�ly.
Abstract: 抗原变异可使得多种致病微生物易于逃避宿主免疫应答。表达在感染红细胞表面的恶性疟原虫红细胞表面蛋白1(PfPMP1)与感染红细胞、内皮细胞、树突状细胞以及胎盘的单个或多个受体作用,在黏附及免疫逃避中起关键的作用。每个单倍体基因组var基因家族编码约60种成员,通过启动转录不同的var基因变异体为抗原变异提供了分子基础。
18,940 citations
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United States Geological Survey1, University of Arizona2, University of Batna3, Oregon State University4, Los Alamos National Laboratory5, Centre national de la recherche scientifique6, Swiss Federal Institute for Forest, Snow and Landscape Research7, Natural Resources Canada8, University of California, Berkeley9, University of Granada10, Northern Research Institute11, Forest Research Institute12, Food and Agriculture Organization13, University of Montana14, Northern Arizona University15
TL;DR: In this paper, the authors present the first global assessment of recent tree mortality attributed to drought and heat stress and identify key information gaps and scientific uncertainties that currently hinder our ability to predict tree mortality in response to climate change and emphasizes the need for a globally coordinated observation system.
5,811 citations
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United States Department of Agriculture1, Peking University2, Chinese Academy of Sciences3, Woods Hole Research Center4, University of Helsinki5, Natural Resources Canada6, University of Leeds7, International Institute for Applied Systems Analysis8, Centre national de la recherche scientifique9, Duke University10, Princeton University11, University of Alaska Fairbanks12, Oak Ridge National Laboratory13
TL;DR: The total forest sink estimate is equivalent in magnitude to the terrestrial sink deduced from fossil fuel emissions and land-use change sources minus ocean and atmospheric sinks, with tropical estimates having the largest uncertainties.
Abstract: The terrestrial carbon sink has been large in recent decades, but its size and location remain uncertain. Using forest inventory data and long-term ecosystem carbon studies, we estimate a total forest sink of 2.4 ± 0.4 petagrams of carbon per year (Pg C year–1) globally for 1990 to 2007. We also estimate a source of 1.3 ± 0.7 Pg C year–1 from tropical land-use change, consisting of a gross tropical deforestation emission of 2.9 ± 0.5 Pg C year–1 partially compensated by a carbon sink in tropical forest regrowth of 1.6 ± 0.5 Pg C year–1. Together, the fluxes comprise a net global forest sink of 1.1 ± 0.8 Pg C year–1, with tropical estimates having the largest uncertainties. Our total forest sink estimate is equivalent in magnitude to the terrestrial sink deduced from fossil fuel emissions and land-use change sources minus ocean and atmospheric sinks.
4,948 citations
01 Jan 2011
3,907 citations
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TL;DR: In this paper, the authors provide a synthesis of past research on the role of soil moisture for the climate system, based both on modelling and observational studies, focusing on soil moisture-temperature and soil moistureprecipitation feedbacks, and their possible modifications with climate change.
3,402 citations