Jean Tirole
- Published in print:
- 2006
- Published Online:
- September 2006
- ISBN:
- 9780195305197
- eISBN:
- 9780199783519
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/0195305191.003.0020
- Subject:
- Economics and Finance, Development, Growth, and Environmental
This essay focuses on the impact of intellectual property rights (IPRs) on low- and middle-income countries’ health care. There are two different reasons why poor countries may not have access to ...
More
This essay focuses on the impact of intellectual property rights (IPRs) on low- and middle-income countries’ health care. There are two different reasons why poor countries may not have access to needed vaccines and drugs. In the case of global diseases, such as diabetes or cancer, patents may hinder the diffusion of pharmaceuticals. In the case of neglected or tropical diseases, such as malaria, tuberculosis, and leishmaniasis, the corresponding vaccines or drugs are not developed because of low profitability due to the poverty of potential customers. The important role of compulsory licensing for low- and middle-income countries is discussed.Less
This essay focuses on the impact of intellectual property rights (IPRs) on low- and middle-income countries’ health care. There are two different reasons why poor countries may not have access to needed vaccines and drugs. In the case of global diseases, such as diabetes or cancer, patents may hinder the diffusion of pharmaceuticals. In the case of neglected or tropical diseases, such as malaria, tuberculosis, and leishmaniasis, the corresponding vaccines or drugs are not developed because of low profitability due to the poverty of potential customers. The important role of compulsory licensing for low- and middle-income countries is discussed.
Michael Kremer
- Published in print:
- 2006
- Published Online:
- September 2006
- ISBN:
- 9780195305197
- eISBN:
- 9780199783519
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/0195305191.003.0021
- Subject:
- Economics and Finance, Development, Growth, and Environmental
This essay focuses on the impact of intellectual property rights (IPRs) on low-and middle-income countries’ health care. There are two different reasons why poor countries may not have access to ...
More
This essay focuses on the impact of intellectual property rights (IPRs) on low-and middle-income countries’ health care. There are two different reasons why poor countries may not have access to needed vaccines and drugs. In the case of global diseases, such as diabetes or cancer, patents may hinder the diffusion of pharmaceuticals. In the case of neglected or tropical diseases, such as malaria, tuberculosis, and leishmaniasis, the corresponding vaccines or drugs are not developed because of low profitability due to the poverty of potential customers. The important role of compulsory licensing for low- and middle-income countries is discussed.Less
This essay focuses on the impact of intellectual property rights (IPRs) on low-and middle-income countries’ health care. There are two different reasons why poor countries may not have access to needed vaccines and drugs. In the case of global diseases, such as diabetes or cancer, patents may hinder the diffusion of pharmaceuticals. In the case of neglected or tropical diseases, such as malaria, tuberculosis, and leishmaniasis, the corresponding vaccines or drugs are not developed because of low profitability due to the poverty of potential customers. The important role of compulsory licensing for low- and middle-income countries is discussed.
Eric Post
- Published in print:
- 2019
- Published Online:
- May 2019
- ISBN:
- 9780691182353
- eISBN:
- 9780691185491
- Item type:
- chapter
- Publisher:
- Princeton University Press
- DOI:
- 10.23943/princeton/9780691182353.003.0009
- Subject:
- Biology, Ecology
This chapter explores patterns of phenological dynamics in tropical systems, where the availability of time is comparatively unconstrained by abiotic conditions. Although abiotic conditions are ...
More
This chapter explores patterns of phenological dynamics in tropical systems, where the availability of time is comparatively unconstrained by abiotic conditions. Although abiotic conditions are conducive to growth and reproduction throughout the year in the tropics, many tropical species exhibit pronounced phenological dynamics that shape and are influenced by their interactions in time with other species. Hence, even though ecological time is abundant in tropical systems, species can still be seen to segregate their phenological activity in time. This is evident in the leaf flushing, flowering, and fruiting activity of many tropical plant species that, while capable of expression of such life history events throughout the year, tend to engage in peaks in such activity that lend structure to the phenological community.Less
This chapter explores patterns of phenological dynamics in tropical systems, where the availability of time is comparatively unconstrained by abiotic conditions. Although abiotic conditions are conducive to growth and reproduction throughout the year in the tropics, many tropical species exhibit pronounced phenological dynamics that shape and are influenced by their interactions in time with other species. Hence, even though ecological time is abundant in tropical systems, species can still be seen to segregate their phenological activity in time. This is evident in the leaf flushing, flowering, and fruiting activity of many tropical plant species that, while capable of expression of such life history events throughout the year, tend to engage in peaks in such activity that lend structure to the phenological community.
Vernon Reynolds
- Published in print:
- 2005
- Published Online:
- September 2007
- ISBN:
- 9780198515463
- eISBN:
- 9780191705656
- Item type:
- book
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780198515463.001.0001
- Subject:
- Biology, Biodiversity / Conservation Biology
Chimpanzees have never been more threatened with extinction than they are today. This book focuses on one chimpanzee group, the Sonso community, living in a tropical rain forest, the Budongo Forest ...
More
Chimpanzees have never been more threatened with extinction than they are today. This book focuses on one chimpanzee group, the Sonso community, living in a tropical rain forest, the Budongo Forest in western Uganda. The book builds up a detailed picture of the forest environment of these apes, their social and behavioural adaptations, and the range of threats they face at the present time. The facts presented in the book summarize the author’s own work and that of the many students and colleagues who have worked with the Budongo Forest Project, which the author founded, over the years from 1990 to the present day. Comparisons are made with other chimpanzee field studies. A picture is built up to show the Sonso community living in a complex environment to which it has adapted well. The diet, culture, social behaviour, and social organization of the chimpanzees are described in detail. Focus then shifts to the various dangers they face in the modern context of increasing pressure from local hunters who put snares in the forest, and from a local agribusiness which threatens to engulf the forest. A careful appraisal of the future for these animals is made, ending with a note of hope for their survival if the national organizations that exist to protect them can become more effective.Less
Chimpanzees have never been more threatened with extinction than they are today. This book focuses on one chimpanzee group, the Sonso community, living in a tropical rain forest, the Budongo Forest in western Uganda. The book builds up a detailed picture of the forest environment of these apes, their social and behavioural adaptations, and the range of threats they face at the present time. The facts presented in the book summarize the author’s own work and that of the many students and colleagues who have worked with the Budongo Forest Project, which the author founded, over the years from 1990 to the present day. Comparisons are made with other chimpanzee field studies. A picture is built up to show the Sonso community living in a complex environment to which it has adapted well. The diet, culture, social behaviour, and social organization of the chimpanzees are described in detail. Focus then shifts to the various dangers they face in the modern context of increasing pressure from local hunters who put snares in the forest, and from a local agribusiness which threatens to engulf the forest. A careful appraisal of the future for these animals is made, ending with a note of hope for their survival if the national organizations that exist to protect them can become more effective.
Sarah Washbrook
- Published in print:
- 2012
- Published Online:
- January 2013
- ISBN:
- 9780197264973
- eISBN:
- 9780191754128
- Item type:
- book
- Publisher:
- British Academy
- DOI:
- 10.5871/bacad/9780197264973.001.0001
- Subject:
- History, Latin American History
Race, ethnicity, and gender played an important role in the complex relationship between export agriculture, labour, and state power in Chiapas during the regime of Porfirio Díaz (1876–1914). This ...
More
Race, ethnicity, and gender played an important role in the complex relationship between export agriculture, labour, and state power in Chiapas during the regime of Porfirio Díaz (1876–1914). This case study of tropical plantation development and major regional study of modern Mexico analyzes the politics of state-building and the history of land tenure and rural labour in the state of Chiapas in the period leading up to the outbreak of Revolution in 1910. The book also contributes to the growing history of indigenous peoples in Latin America, examining the changing relationship between Indian groups and non-Indian governments and economic interests in Chiapas during the nineteenth century. In so doing, it addresses questions of tradition, modernity, national state-building, globalization, and the development of capitalism in Latin America. The book argues that colonial caste identities and relations were no impediments to modernization. Instead, they were modified by liberalism, reinterpreted through the lenses of positivism and scientific racism, and managed through an increasingly centralized state apparatus. Indian communities emerge, then, not solely as oppressed and marginalized, but as an integral part of increasingly centralized state power and as institutions through which growing demands for labour and taxes could be made. Debt peonage, too, was upheld by the liberal state, sanctioned by the law as a natural everyday relationship, and buttressed by traditional patriarchy and gender relationships. Thus, in Chiapas the Porfirian regime recycled and redeployed pre-existing social and political relations, reinventing tradition to serve the purposes of modernization and progress.Less
Race, ethnicity, and gender played an important role in the complex relationship between export agriculture, labour, and state power in Chiapas during the regime of Porfirio Díaz (1876–1914). This case study of tropical plantation development and major regional study of modern Mexico analyzes the politics of state-building and the history of land tenure and rural labour in the state of Chiapas in the period leading up to the outbreak of Revolution in 1910. The book also contributes to the growing history of indigenous peoples in Latin America, examining the changing relationship between Indian groups and non-Indian governments and economic interests in Chiapas during the nineteenth century. In so doing, it addresses questions of tradition, modernity, national state-building, globalization, and the development of capitalism in Latin America. The book argues that colonial caste identities and relations were no impediments to modernization. Instead, they were modified by liberalism, reinterpreted through the lenses of positivism and scientific racism, and managed through an increasingly centralized state apparatus. Indian communities emerge, then, not solely as oppressed and marginalized, but as an integral part of increasingly centralized state power and as institutions through which growing demands for labour and taxes could be made. Debt peonage, too, was upheld by the liberal state, sanctioned by the law as a natural everyday relationship, and buttressed by traditional patriarchy and gender relationships. Thus, in Chiapas the Porfirian regime recycled and redeployed pre-existing social and political relations, reinventing tradition to serve the purposes of modernization and progress.
Oliver L. Phillips, Timothy R. Baker, Luzmila Arroyo, Niro Higuchi, Timothy Killeen, William F. Laurance, Simon L. Lewis, Jon Lloyd, Yadvinder Malhi, Abel Monteagudo, David A. Neill, Percy Nuñez Vargas, J. Natalino N. Silva, Rodolfo Vásquez Martinez, Miguel Alexiades, Samuel Almeida, Sandra Brown, Jerome Chave, James A. Comiskey, Claudia I. Czimczik, Anthony Di Fiore, Terry Erwin, Caroline Kuebler, Susan G. Laurance, Henrique E. M. Nascimento, Jean Olivier, Walter Palacios, Sandra Patiño, Nigel Pitman, Carlos A. Quesada, Mario Saldias, Armando Torres Lezama, and Barbara Vinceti
- Published in print:
- 2005
- Published Online:
- September 2007
- ISBN:
- 9780198567066
- eISBN:
- 9780191717888
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780198567066.003.0010
- Subject:
- Biology, Plant Sciences and Forestry
Previous work found that tree turnover, biomass, and large liana densities increased in mature tropical forests in the late 20th century, indicating a concerted shift in forest ecological processes. ...
More
Previous work found that tree turnover, biomass, and large liana densities increased in mature tropical forests in the late 20th century, indicating a concerted shift in forest ecological processes. However, the findings have proved controversial. Here, regional-scale patterns of tree turnover are characterized, using improved datasets available for Amazonia that span the last twenty-five years. The main findings include: trees at least 10 cm in diameter recruit and die twice as fast on the richer soils of western Amazonia compared to trees on the poorer soils of eastern Amazonia; turnover rates have increased throughout Amazonia over the last two decades; mortality and recruitment rates have tended to increase in every region and environmental zone; recruitment rates consistently exceed mortality rates; and increases in recruitment and mortality rates are greatest in western Amazonia. These patterns and trends are not caused by obvious artefacts in the data or the analyses, and cannot be directly driven by a mortality driver such as increased drought because the biomass in these forests has simultaneously increased. Apparently, therefore, widespread environmental changes are stimulating the growth and productivity of Amazon forests.Less
Previous work found that tree turnover, biomass, and large liana densities increased in mature tropical forests in the late 20th century, indicating a concerted shift in forest ecological processes. However, the findings have proved controversial. Here, regional-scale patterns of tree turnover are characterized, using improved datasets available for Amazonia that span the last twenty-five years. The main findings include: trees at least 10 cm in diameter recruit and die twice as fast on the richer soils of western Amazonia compared to trees on the poorer soils of eastern Amazonia; turnover rates have increased throughout Amazonia over the last two decades; mortality and recruitment rates have tended to increase in every region and environmental zone; recruitment rates consistently exceed mortality rates; and increases in recruitment and mortality rates are greatest in western Amazonia. These patterns and trends are not caused by obvious artefacts in the data or the analyses, and cannot be directly driven by a mortality driver such as increased drought because the biomass in these forests has simultaneously increased. Apparently, therefore, widespread environmental changes are stimulating the growth and productivity of Amazon forests.
Timothy R. Baker, Oliver L. Phillips, Yadvinder Malhi, Samuel Almeida, Luzmila Arroyo, Anthony Di Fiore, Terry Erwin, Niro Higuchi, Timothy J. Killeen, Susan G. Laurance, William F. Laurance, Simon L. Lewis, Abel Monteagudo, David A. Neill, Percy Núnez Vargas, Nigel C. A. Pitman, J. Natalino M. Silva, and Rodolfo Vásquez Martínez
- Published in print:
- 2005
- Published Online:
- September 2007
- ISBN:
- 9780198567066
- eISBN:
- 9780191717888
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780198567066.003.0011
- Subject:
- Biology, Plant Sciences and Forestry
This chapter discusses a previous study by Phillips et al. (1998) on biomass changes in Amazonian permanent sample plots which has been used to infer the presence of a regional carbon sink, ...
More
This chapter discusses a previous study by Phillips et al. (1998) on biomass changes in Amazonian permanent sample plots which has been used to infer the presence of a regional carbon sink, generating vigorous debate about sampling and methodological issues. A new analysis of biomass change in old-growth Amazonian forest plots is presented here using new inventory data. It has been found that across fifty-nine sites, the above-ground dry biomass in trees of more than 10 cm in diameter has increased since plot establishment by about 1.22 Mg per hectare per year, or about 0.98 Mg per hectare per year if individual plot values are weighted by the number of hectare years of monitoring. This significant increase is not confounded by spatial or temporal variation in wood specific gravity, nor does it depend on the allometric equation used to estimate biomass. Overall, these results suggest a slightly greater rate of net stand-level change than reported in 1998, and indicate the presence of a significant regional-scale carbon sink in old-growth Amazonian forests during the past two decades.Less
This chapter discusses a previous study by Phillips et al. (1998) on biomass changes in Amazonian permanent sample plots which has been used to infer the presence of a regional carbon sink, generating vigorous debate about sampling and methodological issues. A new analysis of biomass change in old-growth Amazonian forest plots is presented here using new inventory data. It has been found that across fifty-nine sites, the above-ground dry biomass in trees of more than 10 cm in diameter has increased since plot establishment by about 1.22 Mg per hectare per year, or about 0.98 Mg per hectare per year if individual plot values are weighted by the number of hectare years of monitoring. This significant increase is not confounded by spatial or temporal variation in wood specific gravity, nor does it depend on the allometric equation used to estimate biomass. Overall, these results suggest a slightly greater rate of net stand-level change than reported in 1998, and indicate the presence of a significant regional-scale carbon sink in old-growth Amazonian forests during the past two decades.
Jerome Chave, Guillem Chust, Richard Condit, Salomon Aguilar, Andres Hernandez, Suzanne Lao, and Rolando Perez
- Published in print:
- 2005
- Published Online:
- September 2007
- ISBN:
- 9780198567066
- eISBN:
- 9780191717888
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780198567066.003.0013
- Subject:
- Biology, Plant Sciences and Forestry
The dry above-ground biomass (AGB) of tropical forests is a crucial variable for ecologists, biogeochemists, foresters, and policy makers. Permanent tree inventories provide an efficient way of ...
More
The dry above-ground biomass (AGB) of tropical forests is a crucial variable for ecologists, biogeochemists, foresters, and policy makers. Permanent tree inventories provide an efficient way of assessing this variable. In order to make correct inferences about long-term changes in biomass stocks, it is essential to know the uncertainty associated with AGB estimates, yet this uncertainty is seldom evaluated carefully. Here, four types of uncertainties that could lead to statistical error in AGB estimates are quantified: error due to tree measurement; error due to the choice of allometric model relating AGB to other tree dimensions; sampling uncertainty, related to the size of the study plot; representativeness of a network of small plots across a forest landscape. All four are estimated for a 50-hectare plot on Barro Colorado Island, and for a network of 1-hectare plots scattered across the Panama Canal Watershed, Central Panama. This chapter finds that the most important source of error is currently related to the choice of the allometric model. More work should be devoted to improving the predictive power of allometric models for biomass.Less
The dry above-ground biomass (AGB) of tropical forests is a crucial variable for ecologists, biogeochemists, foresters, and policy makers. Permanent tree inventories provide an efficient way of assessing this variable. In order to make correct inferences about long-term changes in biomass stocks, it is essential to know the uncertainty associated with AGB estimates, yet this uncertainty is seldom evaluated carefully. Here, four types of uncertainties that could lead to statistical error in AGB estimates are quantified: error due to tree measurement; error due to the choice of allometric model relating AGB to other tree dimensions; sampling uncertainty, related to the size of the study plot; representativeness of a network of small plots across a forest landscape. All four are estimated for a 50-hectare plot on Barro Colorado Island, and for a network of 1-hectare plots scattered across the Panama Canal Watershed, Central Panama. This chapter finds that the most important source of error is currently related to the choice of the allometric model. More work should be devoted to improving the predictive power of allometric models for biomass.
Mark Maslin
- Published in print:
- 2005
- Published Online:
- September 2007
- ISBN:
- 9780198567066
- eISBN:
- 9780191717888
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780198567066.003.0014
- Subject:
- Biology, Plant Sciences and Forestry
This chapter highlights and explains the impressive story of the persistence of the Amazonian rainforest throughout the Cenozoic. Palaeoclimate and palaeoecological records suggest that the Amazon ...
More
This chapter highlights and explains the impressive story of the persistence of the Amazonian rainforest throughout the Cenozoic. Palaeoclimate and palaeoecological records suggest that the Amazon rainforest originated in the late Cretaceous and has been a permanent feature of South America for at least the last 55 million years. During the late Palaocene the ‘rainforest’ or ‘megathermal moist forest’ (MTMF) may have stretched as far south as 45°S in South America. The main climatic feature of the last 55 million years has been global cooling and the general constriction of the megathermal moist forests to the tropics. However, the Amazon rainforest has survived the high temperatures of the early Eocene climate optimum and the aridity and low carbon dioxide levels of the Quaternary glacial periods. The Amazon rainforest should, therefore, not be viewed as a geologically ephemeral feature of South America, but rather as a constant feature of the global Cenozoic biosphere. The forest is now, however, entering a set of climatic conditions with no past analogue.Less
This chapter highlights and explains the impressive story of the persistence of the Amazonian rainforest throughout the Cenozoic. Palaeoclimate and palaeoecological records suggest that the Amazon rainforest originated in the late Cretaceous and has been a permanent feature of South America for at least the last 55 million years. During the late Palaocene the ‘rainforest’ or ‘megathermal moist forest’ (MTMF) may have stretched as far south as 45°S in South America. The main climatic feature of the last 55 million years has been global cooling and the general constriction of the megathermal moist forests to the tropics. However, the Amazon rainforest has survived the high temperatures of the early Eocene climate optimum and the aridity and low carbon dioxide levels of the Quaternary glacial periods. The Amazon rainforest should, therefore, not be viewed as a geologically ephemeral feature of South America, but rather as a constant feature of the global Cenozoic biosphere. The forest is now, however, entering a set of climatic conditions with no past analogue.
Francis E. Mayle and Mark B. Bush
- Published in print:
- 2005
- Published Online:
- September 2007
- ISBN:
- 9780198567066
- eISBN:
- 9780191717888
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780198567066.003.0015
- Subject:
- Biology, Plant Sciences and Forestry
This chapter reviews previously published palaeovegetation and independent palaeoclimatic datasets to determine the responses of Amazonian ecosystems to changes in temperature, precipitation, and ...
More
This chapter reviews previously published palaeovegetation and independent palaeoclimatic datasets to determine the responses of Amazonian ecosystems to changes in temperature, precipitation, and atmospheric CO2 concentrations that occurred since the last glacial maximum (LGM), about 21,000 years ago, and it uses this long-term perspective to predict the likely vegetation responses to future climate change. Amazonia remained predominantly forested at the LGM, although savannas expanded at the margins of the basin. The combination of reduced temperatures, precipitation, and atmospheric CO2 concentrations resulted in forests structurally and floristically quite different from those of today. Evergreen rainforest distribution increased during the glacial-Holocene transition due to ameliorating climatic and CO2 conditions. However, reduced precipitation in the early-mid Holocene (about 8000-3600 years ago) period caused widespread, frequent fires in seasonal southern Amazonia, with increased abundance of drought-tolerant dry forest taxa and savanna in ecotonal areas. Rainforests expanded once again in the late Holocene period as a result of increased precipitation. The plant communities that existed during the early-mid Holocene period may constitute the closest analogues to the kinds of vegetation responses expected from similar increases in temperature and aridity posited for the 21st century.Less
This chapter reviews previously published palaeovegetation and independent palaeoclimatic datasets to determine the responses of Amazonian ecosystems to changes in temperature, precipitation, and atmospheric CO2 concentrations that occurred since the last glacial maximum (LGM), about 21,000 years ago, and it uses this long-term perspective to predict the likely vegetation responses to future climate change. Amazonia remained predominantly forested at the LGM, although savannas expanded at the margins of the basin. The combination of reduced temperatures, precipitation, and atmospheric CO2 concentrations resulted in forests structurally and floristically quite different from those of today. Evergreen rainforest distribution increased during the glacial-Holocene transition due to ameliorating climatic and CO2 conditions. However, reduced precipitation in the early-mid Holocene (about 8000-3600 years ago) period caused widespread, frequent fires in seasonal southern Amazonia, with increased abundance of drought-tolerant dry forest taxa and savanna in ecotonal areas. Rainforests expanded once again in the late Holocene period as a result of increased precipitation. The plant communities that existed during the early-mid Holocene period may constitute the closest analogues to the kinds of vegetation responses expected from similar increases in temperature and aridity posited for the 21st century.
Sharon A. Cowling, Richard A. Betts, Peter M. Cox, Virginia J. Ettwein, Chris D. Jones, Mark A. Maslin, and Steven A. Spall
- Published in print:
- 2005
- Published Online:
- September 2007
- ISBN:
- 9780198567066
- eISBN:
- 9780191717888
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780198567066.003.0016
- Subject:
- Biology, Plant Sciences and Forestry
This chapter contrasted HadCM3LC simulations of Amazonian forest at the Last Glacial Maximum (21 kya) and a Younger Dryas-like period (13-12 kya) with predicted responses of future warming to provide ...
More
This chapter contrasted HadCM3LC simulations of Amazonian forest at the Last Glacial Maximum (21 kya) and a Younger Dryas-like period (13-12 kya) with predicted responses of future warming to provide estimates of the climatic limits under which the Amazon forest remains relatively stable. Simulations indicate that despite lower atmospheric CO2 concentrations and increased aridity during the LGM, Amazonia remains mostly forested, and that the cooler climate of the Younger Dryas-like period in fact causes a trend towards increased above-ground carbon balance relative to today. The vegetation feedbacks responsible for maintaining forest integrity in past climates (i.e. decreased evapotranspiration and reduced photorespiration) cannot be maintained in the future. Although elevated atmospheric CO2 contributes to a positive enhancement of plant carbon and water balance, decreased stomatal conductance and increased plant and soil respiration cause a positive feedback that amplifies localised drying and climate warming. The Amazonian forest appears to be presently near its critical resiliency threshold, and even minor climate warming may be sufficient to promote deleterious feedbacks on forest integrity.Less
This chapter contrasted HadCM3LC simulations of Amazonian forest at the Last Glacial Maximum (21 kya) and a Younger Dryas-like period (13-12 kya) with predicted responses of future warming to provide estimates of the climatic limits under which the Amazon forest remains relatively stable. Simulations indicate that despite lower atmospheric CO2 concentrations and increased aridity during the LGM, Amazonia remains mostly forested, and that the cooler climate of the Younger Dryas-like period in fact causes a trend towards increased above-ground carbon balance relative to today. The vegetation feedbacks responsible for maintaining forest integrity in past climates (i.e. decreased evapotranspiration and reduced photorespiration) cannot be maintained in the future. Although elevated atmospheric CO2 contributes to a positive enhancement of plant carbon and water balance, decreased stomatal conductance and increased plant and soil respiration cause a positive feedback that amplifies localised drying and climate warming. The Amazonian forest appears to be presently near its critical resiliency threshold, and even minor climate warming may be sufficient to promote deleterious feedbacks on forest integrity.
R. Toby Pennington, Matt Lavin, Darién E. Prado, Colin A. Pendry, and Susan K. Pell
- Published in print:
- 2005
- Published Online:
- September 2007
- ISBN:
- 9780198567066
- eISBN:
- 9780191717888
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780198567066.003.0017
- Subject:
- Biology, Plant Sciences and Forestry
Historical climate changes have had a major effect on the distribution and evolution of plant species in the neotropics. What is more controversial is whether relatively recent and rapid Pleistocene ...
More
Historical climate changes have had a major effect on the distribution and evolution of plant species in the neotropics. What is more controversial is whether relatively recent and rapid Pleistocene climatic changes have driven speciation, or whether neotropical species diversity is more ancient. This question is addressed using evolutionary rates analysis of nuclear ribosomal internal transcribed spacers (ITS) sequence data on diverse taxa occupying neotropical seasonally dry forests: Ruprechtia (Polygonaceae), robinioid legumes (Leguminosae), Chaetocalyx and Nissolia (Leguminosae), and Loxopterygium (Anacardiaceae). Species diversifications in these taxa occurred both during and before the Pleistocene in Central America, but were primarily pre-Pleistocene in South America. This indicates plausibility both for models that predict tropical species diversity to be recent and that invoke a role for Pleistocene climatic change, and those that consider it ancient and implicate geological factors such as the Andean orogeny and the closure of the Panama Isthmus.Less
Historical climate changes have had a major effect on the distribution and evolution of plant species in the neotropics. What is more controversial is whether relatively recent and rapid Pleistocene climatic changes have driven speciation, or whether neotropical species diversity is more ancient. This question is addressed using evolutionary rates analysis of nuclear ribosomal internal transcribed spacers (ITS) sequence data on diverse taxa occupying neotropical seasonally dry forests: Ruprechtia (Polygonaceae), robinioid legumes (Leguminosae), Chaetocalyx and Nissolia (Leguminosae), and Loxopterygium (Anacardiaceae). Species diversifications in these taxa occurred both during and before the Pleistocene in Central America, but were primarily pre-Pleistocene in South America. This indicates plausibility both for models that predict tropical species diversity to be recent and that invoke a role for Pleistocene climatic change, and those that consider it ancient and implicate geological factors such as the Andean orogeny and the closure of the Panama Isthmus.
Oliver L. Phillips and Yadvinder Malhi
- Published in print:
- 2005
- Published Online:
- September 2007
- ISBN:
- 9780198567066
- eISBN:
- 9780191717888
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780198567066.003.0018
- Subject:
- Biology, Plant Sciences and Forestry
At the start of the 21st century the human race lives in a radically altered biosphere, and in an atmosphere that is shifting rapidly to conditions with no direct analogue in Earth's prehistory. ...
More
At the start of the 21st century the human race lives in a radically altered biosphere, and in an atmosphere that is shifting rapidly to conditions with no direct analogue in Earth's prehistory. These atmospheric changes are certain to have impacts on the Earth's ecosystems, but the complexity of these ecosystems and the multiplicity of processes and scales make the exact nature of these impacts difficult to tease out. This book has examined the potential impacts on the most complex of terrestrial ecosystems, the great tropical forests, and addresses the important question: what will (any remaining) mature old-growth tropical forests look like at the end of this century? Answering this question has implications for conservation, global biodiversity, and global biogeochemical cycling, as well as being a test for our understanding of natural- and human-impacted ecosystems.Less
At the start of the 21st century the human race lives in a radically altered biosphere, and in an atmosphere that is shifting rapidly to conditions with no direct analogue in Earth's prehistory. These atmospheric changes are certain to have impacts on the Earth's ecosystems, but the complexity of these ecosystems and the multiplicity of processes and scales make the exact nature of these impacts difficult to tease out. This book has examined the potential impacts on the most complex of terrestrial ecosystems, the great tropical forests, and addresses the important question: what will (any remaining) mature old-growth tropical forests look like at the end of this century? Answering this question has implications for conservation, global biodiversity, and global biogeochemical cycling, as well as being a test for our understanding of natural- and human-impacted ecosystems.
Yadvinder Malhi and James Wright
- Published in print:
- 2005
- Published Online:
- September 2007
- ISBN:
- 9780198567066
- eISBN:
- 9780191717888
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780198567066.003.0001
- Subject:
- Biology, Plant Sciences and Forestry
This chapter presents an analysis of the mean climate and climatic trends of tropical rainforest regions over the period 1960-98, with the aid of climatological databases. Since the mid-1970s all ...
More
This chapter presents an analysis of the mean climate and climatic trends of tropical rainforest regions over the period 1960-98, with the aid of climatological databases. Since the mid-1970s all tropical rainforest regions have experienced a warming, in synchrony with a global rise in temperature that has been attributed to the anthropogenic greenhouse effect. Over the study period precipitation appears to have declined sharply in northern tropical Africa, declined marginally in tropical Asia, and showed no significant trend in Amazonia. There is no evidence to date of a decline in precipitation in eastern Amazonia, a region thought vulnerable to climate-change induced drying. The strong drying trend in Africa suggests that this should be a priority study region for understanding the impact of drought on tropical rainforests. Only African and Indian tropical rainforests appear to have seen a significant increase in dry season intensity. The El Niñno-Southern Oscillation is the primary driver of interannual temperature variations across the tropics, and of precipitation fluctuations for large areas of the Americas and Southeast Asia.Less
This chapter presents an analysis of the mean climate and climatic trends of tropical rainforest regions over the period 1960-98, with the aid of climatological databases. Since the mid-1970s all tropical rainforest regions have experienced a warming, in synchrony with a global rise in temperature that has been attributed to the anthropogenic greenhouse effect. Over the study period precipitation appears to have declined sharply in northern tropical Africa, declined marginally in tropical Asia, and showed no significant trend in Amazonia. There is no evidence to date of a decline in precipitation in eastern Amazonia, a region thought vulnerable to climate-change induced drying. The strong drying trend in Africa suggests that this should be a priority study region for understanding the impact of drought on tropical rainforests. Only African and Indian tropical rainforests appear to have seen a significant increase in dry season intensity. The El Niñno-Southern Oscillation is the primary driver of interannual temperature variations across the tropics, and of precipitation fluctuations for large areas of the Americas and Southeast Asia.
Wolfgang Cramer, Alberte Bondeau, Sibyll Schaphoff, Wolfgang Lucht, Ben Smith, and Stephen Sitch
- Published in print:
- 2005
- Published Online:
- September 2007
- ISBN:
- 9780198567066
- eISBN:
- 9780191717888
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780198567066.003.0002
- Subject:
- Biology, Plant Sciences and Forestry
This chapter quantifies the relative roles of carbon dioxide (CO2), temperature, rainfall, and deforestation on the future extent and condition of tropical rainforests, and examines the magnitude of ...
More
This chapter quantifies the relative roles of carbon dioxide (CO2), temperature, rainfall, and deforestation on the future extent and condition of tropical rainforests, and examines the magnitude of their feedbacks on atmospheric CO2 concentrations. A dynamic global vegetation model is applied using multiple scenarios of tropical deforestation (extrapolated from two estimates of current rates) and multiple scenarios of changing climate (derived from four independent off-line general circulation model simulations). Results show that deforestation is likely to produce large losses of carbon, despite the uncertainty concerning exact deforestation rates. Estimates of additional carbon emissions during the 21st century, for all climate and deforestation scenarios, range from 101 to 367 Gt C, resulting in CO2 concentration increases above background values by between 29 and 129 ppm. Notwithstanding this range of uncertainty, continued tropical deforestation will most certainly play a very large role in the build-up of future greenhouse gas concentrations.Less
This chapter quantifies the relative roles of carbon dioxide (CO2), temperature, rainfall, and deforestation on the future extent and condition of tropical rainforests, and examines the magnitude of their feedbacks on atmospheric CO2 concentrations. A dynamic global vegetation model is applied using multiple scenarios of tropical deforestation (extrapolated from two estimates of current rates) and multiple scenarios of changing climate (derived from four independent off-line general circulation model simulations). Results show that deforestation is likely to produce large losses of carbon, despite the uncertainty concerning exact deforestation rates. Estimates of additional carbon emissions during the 21st century, for all climate and deforestation scenarios, range from 101 to 367 Gt C, resulting in CO2 concentration increases above background values by between 29 and 129 ppm. Notwithstanding this range of uncertainty, continued tropical deforestation will most certainly play a very large role in the build-up of future greenhouse gas concentrations.
Simon L. Lewis, Yadvinder Malhi, and Oliver L. Phillips
- Published in print:
- 2005
- Published Online:
- September 2007
- ISBN:
- 9780198567066
- eISBN:
- 9780191717888
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780198567066.003.0004
- Subject:
- Biology, Plant Sciences and Forestry
Recent observations of widespread changes in mature tropical forests such as a rise in tree growth, recruitment and mortality, and above-ground biomass, suggest that ‘global change’ agents may be ...
More
Recent observations of widespread changes in mature tropical forests such as a rise in tree growth, recruitment and mortality, and above-ground biomass, suggest that ‘global change’ agents may be affecting tropical forests far from the deforestation fronts. However, consensus has yet to emerge over the robustness of these changes and the environmental drivers that may be causing them. This chapter focuses on the second part of this debate. Ten potential widespread drivers of environmental change are identified: temperature, precipitation, solar radiation, climatic extremes (including El Niñno-Southern Oscillation events), atmospheric CO2 concentrations, nutrient deposition, O3/acid depositions, hunting, land-use change, and increasing liana numbers. Each is expected to leave a unique ‘fingerprint’ in tropical forests, as drivers directly force different processes, have different distributions in space and time and may affect some forests more than others (e.g., depending on soil fertility). Testable a priori predictions of forest responses are presented to help ecologists attribute particular changes in forests to particular causes. Finally, this chapter discusses how these drivers may change and the possible future consequences for tropical forests.Less
Recent observations of widespread changes in mature tropical forests such as a rise in tree growth, recruitment and mortality, and above-ground biomass, suggest that ‘global change’ agents may be affecting tropical forests far from the deforestation fronts. However, consensus has yet to emerge over the robustness of these changes and the environmental drivers that may be causing them. This chapter focuses on the second part of this debate. Ten potential widespread drivers of environmental change are identified: temperature, precipitation, solar radiation, climatic extremes (including El Niñno-Southern Oscillation events), atmospheric CO2 concentrations, nutrient deposition, O3/acid depositions, hunting, land-use change, and increasing liana numbers. Each is expected to leave a unique ‘fingerprint’ in tropical forests, as drivers directly force different processes, have different distributions in space and time and may affect some forests more than others (e.g., depending on soil fertility). Testable a priori predictions of forest responses are presented to help ecologists attribute particular changes in forests to particular causes. Finally, this chapter discusses how these drivers may change and the possible future consequences for tropical forests.
Jeffrey Q. Chambers and Whendee L. Silver
- Published in print:
- 2005
- Published Online:
- September 2007
- ISBN:
- 9780198567066
- eISBN:
- 9780191717888
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780198567066.003.0005
- Subject:
- Biology, Plant Sciences and Forestry
There are several atmospheric changes that may affect physiological and biogeochemical processes in old-growth tropical forests. Elevated CO2 is likely to directly influence numerous leaf-level ...
More
There are several atmospheric changes that may affect physiological and biogeochemical processes in old-growth tropical forests. Elevated CO2 is likely to directly influence numerous leaf-level physiological processes. To assess potential ecosystem-level responses for a Central Amazon forest, an individual-tree-based carbon cycling model was used to carry out a model experiment constituting experimentally-observed tree growth rate increases linked to the known and expected increase in atmospheric CO2. The results suggested a maximum carbon sequestration rate of only 0.05 Mg C ha-1 yr-1 for an interval centred on 1980-2020. This low sequestration rate results from slow-growing trees and the long residence time of carbon in woody tissues. In contrast, changes in disturbance frequency, precipitation, and other factors can cause marked and relatively rapid losses and gains in ecosystem carbon storage. Observed changes in tropical forest inventory plots over the past few decades may be driven by changes in disturbance regimes and factors, rather than by a response to elevated CO2. Whether observed changes in tropical forests are the beginning of long-term permanent shifts or a transient response is still uncertain.Less
There are several atmospheric changes that may affect physiological and biogeochemical processes in old-growth tropical forests. Elevated CO2 is likely to directly influence numerous leaf-level physiological processes. To assess potential ecosystem-level responses for a Central Amazon forest, an individual-tree-based carbon cycling model was used to carry out a model experiment constituting experimentally-observed tree growth rate increases linked to the known and expected increase in atmospheric CO2. The results suggested a maximum carbon sequestration rate of only 0.05 Mg C ha-1 yr-1 for an interval centred on 1980-2020. This low sequestration rate results from slow-growing trees and the long residence time of carbon in woody tissues. In contrast, changes in disturbance frequency, precipitation, and other factors can cause marked and relatively rapid losses and gains in ecosystem carbon storage. Observed changes in tropical forest inventory plots over the past few decades may be driven by changes in disturbance regimes and factors, rather than by a response to elevated CO2. Whether observed changes in tropical forests are the beginning of long-term permanent shifts or a transient response is still uncertain.
Christian Körner
- Published in print:
- 2005
- Published Online:
- September 2007
- ISBN:
- 9780198567066
- eISBN:
- 9780191717888
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780198567066.003.0006
- Subject:
- Biology, Plant Sciences and Forestry
The fixation and storage of carbon by tropical forests, which contain close to half of the globe's biomass carbon, may be affected by elevated atmospheric CO2 concentration. Classical theoretical ...
More
The fixation and storage of carbon by tropical forests, which contain close to half of the globe's biomass carbon, may be affected by elevated atmospheric CO2 concentration. Classical theoretical approaches assume a uniform stimulation of photosynthesis and growth across taxa. Direct assessments of the carbon balance either by flux studies or by repeated forest inventories also suggest a current net uptake, although magnitudes sometimes exceed those missing in the global C-balance. Reasons for such discrepancies may lie in the nature of forest dynamics and in differential responses of taxa or plant functional types. This contribution argues that CO2 enrichment may cause forests to become more dynamic and that faster tree turnover may convert a stimulatory effect of elevated CO2 on photosynthesis and growth into a long-term net biomass carbon loss by favouring shorter lived trees of lower wood density. At the very least, this is a scenario which deserves inclusion into long-term projections in the carbon relations of tropical forests. Species and plant functional type specific responses (‘biodiversity effects’) and forest dynamics need to be accounted for in projections of future carbon-storage in tropical forests.Less
The fixation and storage of carbon by tropical forests, which contain close to half of the globe's biomass carbon, may be affected by elevated atmospheric CO2 concentration. Classical theoretical approaches assume a uniform stimulation of photosynthesis and growth across taxa. Direct assessments of the carbon balance either by flux studies or by repeated forest inventories also suggest a current net uptake, although magnitudes sometimes exceed those missing in the global C-balance. Reasons for such discrepancies may lie in the nature of forest dynamics and in differential responses of taxa or plant functional types. This contribution argues that CO2 enrichment may cause forests to become more dynamic and that faster tree turnover may convert a stimulatory effect of elevated CO2 on photosynthesis and growth into a long-term net biomass carbon loss by favouring shorter lived trees of lower wood density. At the very least, this is a scenario which deserves inclusion into long-term projections in the carbon relations of tropical forests. Species and plant functional type specific responses (‘biodiversity effects’) and forest dynamics need to be accounted for in projections of future carbon-storage in tropical forests.
Patrick Meir and John Grace
- Published in print:
- 2005
- Published Online:
- September 2007
- ISBN:
- 9780198567066
- eISBN:
- 9780191717888
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780198567066.003.0007
- Subject:
- Biology, Plant Sciences and Forestry
Drought stress in tropical forests can have a major impact on global carbon, water, and energy cycles. This chapter examines drought-induced responses in the processing of carbon and water by intact ...
More
Drought stress in tropical forests can have a major impact on global carbon, water, and energy cycles. This chapter examines drought-induced responses in the processing of carbon and water by intact tropical forest ecosystems over short (physiological) and longer (ecological) timescales. Both levels of understanding should be represented in analyses of climate-forest ecosystem feedback. Although limited spatial information on the diversity of the physical properties of soil constrains estimates of drought vulnerability, tree functional convergence across species based on simple measures such as wood density would simplify how drought responses can be represented and linked to changes in forest composition through mortality indices. While insufficient on their own, satellite-derived measurements of ecosystem properties (e.g. leaf area index) and processes (e.g. mortality and photosynthesis) are expected to provide increasingly detailed information that can be used to test understanding of short- and longer-term responses to drought.Less
Drought stress in tropical forests can have a major impact on global carbon, water, and energy cycles. This chapter examines drought-induced responses in the processing of carbon and water by intact tropical forest ecosystems over short (physiological) and longer (ecological) timescales. Both levels of understanding should be represented in analyses of climate-forest ecosystem feedback. Although limited spatial information on the diversity of the physical properties of soil constrains estimates of drought vulnerability, tree functional convergence across species based on simple measures such as wood density would simplify how drought responses can be represented and linked to changes in forest composition through mortality indices. While insufficient on their own, satellite-derived measurements of ecosystem properties (e.g. leaf area index) and processes (e.g. mortality and photosynthesis) are expected to provide increasingly detailed information that can be used to test understanding of short- and longer-term responses to drought.
William F. Laurance, Alexandre A. Oliveira, Susan G. Laurance, Richard Condit, Henrique E. M. Nascimento, Ana Andrade, Christopher W. Dick, Ana C. Sanchez-Thorin, Thomas E. Lovejoy, and José E. L. S. Ribeiro
- Published in print:
- 2005
- Published Online:
- September 2007
- ISBN:
- 9780198567066
- eISBN:
- 9780191717888
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780198567066.003.0009
- Subject:
- Biology, Plant Sciences and Forestry
The rainforests of central Amazonia are some of the most species-rich tree communities on earth. In recent decades, forests in the central-Amazonian landscape have experienced highly non-random ...
More
The rainforests of central Amazonia are some of the most species-rich tree communities on earth. In recent decades, forests in the central-Amazonian landscape have experienced highly non-random changes in dynamics and composition. These analyses are made on a network of eighteen permanent plots unaffected by any detectable disturbance. Within these plots, tree mortality, recruitment, and growth have increased over time. Of 115 relatively abundant tree genera, twenty-seven changed significantly in density or basal area — a value nearly fourteen times greater than that expected by chance. An independent, eight-year study in nearby forests corroborated these shifts in composition. Despite increasing tree mortality, pioneer trees did not increase in abundance, but genera of faster-growing trees, including many canopy and emergent species, are increasing in dominance or density, whereas genera of slower-growing trees, including many subcanopy species, are declining. Rising atmospheric CO2 concentrations may explain these changes, although the effects of this and other large-scale environmental alterations have not been fully explored. These compositional changes could have important effects on the carbon storage, dynamics, and biota of Amazonian forests.Less
The rainforests of central Amazonia are some of the most species-rich tree communities on earth. In recent decades, forests in the central-Amazonian landscape have experienced highly non-random changes in dynamics and composition. These analyses are made on a network of eighteen permanent plots unaffected by any detectable disturbance. Within these plots, tree mortality, recruitment, and growth have increased over time. Of 115 relatively abundant tree genera, twenty-seven changed significantly in density or basal area — a value nearly fourteen times greater than that expected by chance. An independent, eight-year study in nearby forests corroborated these shifts in composition. Despite increasing tree mortality, pioneer trees did not increase in abundance, but genera of faster-growing trees, including many canopy and emergent species, are increasing in dominance or density, whereas genera of slower-growing trees, including many subcanopy species, are declining. Rising atmospheric CO2 concentrations may explain these changes, although the effects of this and other large-scale environmental alterations have not been fully explored. These compositional changes could have important effects on the carbon storage, dynamics, and biota of Amazonian forests.
