Amazonian and neotropical plant communities on glacial time-scales : the failure of the aridity and refuge hypotheses / P.A. Colinvaux (1999)

Public ISBD Titre : Amazonian and neotropical plant communities on glacial time-scales : the failure of the aridity and refuge hypotheses Type de document : texte imprimé Auteurs : P.A. Colinvaux ; P.E. de Oliveira ; M.B. Bush Editeur : Elsevier Science Année de publication : 1999 Collection : Quaternary Science Reviews, ISSN 0277-3791 num. 19 Importance : pp. 141-169., ill., graph. tabl. nb réf. Langues : Anglais (eng) Catégories : Autres descripteurs CLIMATIC CHANGE ; PLEISTOCENE ; HOLOCENE Thésaurus Agrovoc Amazonie ; Glace ; Pollen Résumé : Plants respond to Pleistocene climatic change as species, not as associations or biomes. This has been demonstrated unequivocally by paleo botanical data for temperate latitudes. In the far richer vegetations of the tropics species populations also fluctuated independently in response to climatic forcing, from their longlasting glacial states to the patterns of brief interglacials like the present and back again. We use pollen data to reconstruct the vegetation of the Amazon basin in oxygen isotope stages 3 and 2 of the last glaciation in order to measure how the plant population of the Amazon responded to the global warming at the onset of the Holocene. We find that plant communities of the neotropics vent copious pollen to lake sediments and that this pollen yields powerful signals for community composition. Three continuous sdimentary records reaching through oxygen isotope stage 2 are available from the Amazon lowland, those from Carajas, Lake Pata and marine deposits of the mouth of the Amazon River. All three records yield pollen histories of remarkable constancy and stability. By comparing them with deposits of equal antiquity from the cerrado (savanna) of central Brazil, we show that most of the Amazon lowlands ramained under forest throughout a glacial cycle. This forest was never fragmented by open vegetation as postulated by the refugia hypothesis. Instead the intact forest of glacial times included significant populations of plants that are now montane, suggesting that the global warming of the early Holocene resulted in the expulsion of heat intolerant plants from the lowland forest. Pollen data from the Amazonian flank of the Andes and from Pacific Panama provide evidence that populations of these heat intolerant plants survive the heat of interglacials in part by maintaining large populations at cooler montane altitudes. our conclusion that the Amazon lowlands were forested in glacial times specifically refutes the hypothesis of Amazonian glacial aridity. Accordingly we examine the geomorphological evidence for glacial aridity and find it wanting. Or the three paleodune systems reported for tropical South America, that of NE Brazil was active in the Holocene as well as the Pleistocene. Parts of NE Brazil were actually moister than now in late glacial times. Paleodunes in the Pantanal have never been seen on the ground, and those in the Orinoco Llanos are undated and may be of any age since the Tertiary. Arkosic sands in the Amazon fan deposits came from the Andean foothills or from down cutting by rivers and cannot be evidence of a former arid land surface. White sands of Amazonia formed as podzols, not by aeolian activity. Such Amazonian stone lines as have received critical scrutiny are concretionary pisolites in stratigraphic formations that are more than ten million years old. Although the Amazon was never arid, modeling cooler glacial tropics gives palusibility to a somewhat drier Amazon in glacial times, a concept given substance by pollen data for the movement of ecotones in Rondonia, by stream histories in the Bolivian Andes, and by evidence for lowered lake levels at Carajas and Lake Pata. But this reduced precipitation was never enough to fragment the forest in the Amazon lowlands themselves. Pleistocene mammals of the Napo river valley in Ecuador wera able to live along the river system in a forested landscape. Our data suggest that the Amazon forests have been stable since the start of the Pleistocene, a fact that has contributed to the storage of vast diversity. The coming anthropogenic global warming and CO2 enrichment will add to the global warming already endured by Amazon biota in the Holocene. We think is possible that the expulsion from the lowland forests of heat intolerant species is already complete and that the forest property of maintaining ist own microhabitat will allow the high species richness to survive more global warming, provided large enough tracts of forest are preserved. Type de document : Tiré à part Permalien de la notice : https://infodoc.agroparistech.fr/index.php?lvl=notice_display&id=151454 Amazonian and neotropical plant communities on glacial time-scales : the failure of the aridity and refuge hypotheses [texte imprimé] / P.A. Colinvaux ; P.E. de Oliveira ; M.B. Bush . - [S.l.] : Elsevier Science, 1999 . - pp. 141-169., ill., graph. tabl. nb réf.. - (Quaternary Science Reviews, ISSN 0277-3791; 19) . Langues : Anglais (eng) Catégories : Autres descripteurs CLIMATIC CHANGE ; PLEISTOCENE ; HOLOCENE Thésaurus Agrovoc Amazonie ; Glace ; Pollen Résumé : Plants respond to Pleistocene climatic change as species, not as associations or biomes. This has been demonstrated unequivocally by paleo botanical data for temperate latitudes. In the far richer vegetations of the tropics species populations also fluctuated independently in response to climatic forcing, from their longlasting glacial states to the patterns of brief interglacials like the present and back again. We use pollen data to reconstruct the vegetation of the Amazon basin in oxygen isotope stages 3 and 2 of the last glaciation in order to measure how the plant population of the Amazon responded to the global warming at the onset of the Holocene. We find that plant communities of the neotropics vent copious pollen to lake sediments and that this pollen yields powerful signals for community composition. Three continuous sdimentary records reaching through oxygen isotope stage 2 are available from the Amazon lowland, those from Carajas, Lake Pata and marine deposits of the mouth of the Amazon River. All three records yield pollen histories of remarkable constancy and stability. By comparing them with deposits of equal antiquity from the cerrado (savanna) of central Brazil, we show that most of the Amazon lowlands ramained under forest throughout a glacial cycle. This forest was never fragmented by open vegetation as postulated by the refugia hypothesis. Instead the intact forest of glacial times included significant populations of plants that are now montane, suggesting that the global warming of the early Holocene resulted in the expulsion of heat intolerant plants from the lowland forest. Pollen data from the Amazonian flank of the Andes and from Pacific Panama provide evidence that populations of these heat intolerant plants survive the heat of interglacials in part by maintaining large populations at cooler montane altitudes. our conclusion that the Amazon lowlands were forested in glacial times specifically refutes the hypothesis of Amazonian glacial aridity. Accordingly we examine the geomorphological evidence for glacial aridity and find it wanting. Or the three paleodune systems reported for tropical South America, that of NE Brazil was active in the Holocene as well as the Pleistocene. Parts of NE Brazil were actually moister than now in late glacial times. Paleodunes in the Pantanal have never been seen on the ground, and those in the Orinoco Llanos are undated and may be of any age since the Tertiary. Arkosic sands in the Amazon fan deposits came from the Andean foothills or from down cutting by rivers and cannot be evidence of a former arid land surface. White sands of Amazonia formed as podzols, not by aeolian activity. Such Amazonian stone lines as have received critical scrutiny are concretionary pisolites in stratigraphic formations that are more than ten million years old. Although the Amazon was never arid, modeling cooler glacial tropics gives palusibility to a somewhat drier Amazon in glacial times, a concept given substance by pollen data for the movement of ecotones in Rondonia, by stream histories in the Bolivian Andes, and by evidence for lowered lake levels at Carajas and Lake Pata. But this reduced precipitation was never enough to fragment the forest in the Amazon lowlands themselves. Pleistocene mammals of the Napo river valley in Ecuador wera able to live along the river system in a forested landscape. Our data suggest that the Amazon forests have been stable since the start of the Pleistocene, a fact that has contributed to the storage of vast diversity. The coming anthropogenic global warming and CO2 enrichment will add to the global warming already endured by Amazon biota in the Holocene. We think is possible that the expulsion from the lowland forests of heat intolerant species is already complete and that the forest property of maintaining ist own microhabitat will allow the high species richness to survive more global warming, provided large enough tracts of forest are preserved. Type de document : Tiré à part Permalien de la notice : https://infodoc.agroparistech.fr/index.php?lvl=notice_display&id=151454

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Amazonian speciation : a necessarily complex model / M.B. Bush (1994)

Public ISBD Titre : Amazonian speciation : a necessarily complex model Type de document : texte imprimé Auteurs : M.B. Bush Année de publication : 1994 Importance : p. 5-17., 1 ill., 1 graph., 4 cartes., nb réf. Langues : Anglais (eng) Catégories : Autres descripteurs AMAZON ; CLIMATE CHANGE ; COOLING ; FOSSIL POLLEN ; PHYLLOGENY ; PLEISTOCENE REFUGIA ; RAIN FOREST ; SAVANNA ; SPECIATION Type de document : Tiré à part Permalien de la notice : https://infodoc.agroparistech.fr/index.php?lvl=notice_display&id=150997 Amazonian speciation : a necessarily complex model [texte imprimé] / M.B. Bush . - 1994 . - p. 5-17., 1 ill., 1 graph., 4 cartes., nb réf. Langues : Anglais (eng) Catégories : Autres descripteurs AMAZON ; CLIMATE CHANGE ; COOLING ; FOSSIL POLLEN ; PHYLLOGENY ; PLEISTOCENE REFUGIA ; RAIN FOREST ; SAVANNA ; SPECIATION Type de document : Tiré à part Permalien de la notice : https://infodoc.agroparistech.fr/index.php?lvl=notice_display&id=150997

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A long pollen record from lowland amazonia : forest and cooling in glacial times / P.A. Colinvaux (1996)

Public ISBD Titre : A long pollen record from lowland amazonia : forest and cooling in glacial times Type de document : texte imprimé Auteurs : P.A. Colinvaux ; P.E. de Oliveira ; J.E. Moreno ; M.C. Miller ; M.B. Bush Editeur : American Association for the Advancement of Science Année de publication : 1996 Collection : Science num. 274 Importance : pp. 85-88., ill., graph., 24 réf. Langues : Anglais (eng) Type de document : Tiré à part Permalien de la notice : https://infodoc.agroparistech.fr/index.php?lvl=notice_display&id=151449 A long pollen record from lowland amazonia : forest and cooling in glacial times [texte imprimé] / P.A. Colinvaux ; P.E. de Oliveira ; J.E. Moreno ; M.C. Miller ; M.B. Bush . - [S.l.] : American Association for the Advancement of Science, 1996 . - pp. 85-88., ill., graph., 24 réf.. - (Science; 274) . Langues : Anglais (eng) Type de document : Tiré à part Permalien de la notice : https://infodoc.agroparistech.fr/index.php?lvl=notice_display&id=151449

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Temperature depression in the lowland tropics in glacial times / P.A. Colinvaux (1996)

Public ISBD Titre : Temperature depression in the lowland tropics in glacial times Type de document : texte imprimé Auteurs : P.A. Colinvaux ; K.B. Liu ; P. de Oliveira ; M.B. Bush ; M.C. Miller ; M. Steinitz Kannan Editeur : Kluwer academic publishers Année de publication : 1996 Collection : Climatic Change num. 32 Importance : pp. 19-33., nb réf. Langues : Anglais (eng) Résumé : Equatorial air temperatures at low elevations in the New World tropics are shown by pollen and other data to have been significantly lowered in long intervals of the last glaciation. These new data show that long recognized evidence for cooling at high elevations in the tropics were symptomatic of general tropical cooling and that they did not require appeal to altered lapse rates or other special mechanisms to be made to conform with conclusions that equatorial sea surface temperatures (SSTs) were scarcely changed in glacial times. The new data should be read in conjonction with recent findings that Caribbean (SSTs) were lowered in the order of 5°C, contrary to previous interpretations. Thus these accumulating data show that low latitudes as well as high were cooled in glaciations. in part the earlier failure to find evidence of low elevation cooling in the lowland tropics resulted from the data being masked by strong signals for aridity given by old lake levels in parts of Africa and elsewhere. Global circulation models used to predict future effects of greenhouse warming must also be able to simulate the significant cooling of the large tropical land masses at glacial times with greenhouse gas concentrations. Plants and animals of the Amazon forest and similar ecosystems are able to survive in wide ranges of temperates, CO2 concentrations, and disturbance, though associations change constantly. Type de document : Tiré à part Permalien de la notice : https://infodoc.agroparistech.fr/index.php?lvl=notice_display&id=151453 Temperature depression in the lowland tropics in glacial times [texte imprimé] / P.A. Colinvaux ; K.B. Liu ; P. de Oliveira ; M.B. Bush ; M.C. Miller ; M. Steinitz Kannan . - [S.l.] : Kluwer academic publishers, 1996 . - pp. 19-33., nb réf.. - (Climatic Change; 32) . Langues : Anglais (eng) Résumé : Equatorial air temperatures at low elevations in the New World tropics are shown by pollen and other data to have been significantly lowered in long intervals of the last glaciation. These new data show that long recognized evidence for cooling at high elevations in the tropics were symptomatic of general tropical cooling and that they did not require appeal to altered lapse rates or other special mechanisms to be made to conform with conclusions that equatorial sea surface temperatures (SSTs) were scarcely changed in glacial times. The new data should be read in conjonction with recent findings that Caribbean (SSTs) were lowered in the order of 5°C, contrary to previous interpretations. Thus these accumulating data show that low latitudes as well as high were cooled in glaciations. in part the earlier failure to find evidence of low elevation cooling in the lowland tropics resulted from the data being masked by strong signals for aridity given by old lake levels in parts of Africa and elsewhere. Global circulation models used to predict future effects of greenhouse warming must also be able to simulate the significant cooling of the large tropical land masses at glacial times with greenhouse gas concentrations. Plants and animals of the Amazon forest and similar ecosystems are able to survive in wide ranges of temperates, CO2 concentrations, and disturbance, though associations change constantly. Type de document : Tiré à part Permalien de la notice : https://infodoc.agroparistech.fr/index.php?lvl=notice_display&id=151453

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Tropical rainforest responses to climatic change / M.B. Bush (2007)

Public ISBD Titre : Tropical rainforest responses to climatic change Type de document : texte imprimé Auteurs : M.B. Bush ; R. Flenley Editeur : Berlin : Springer-Praxis Année de publication : 2007 Importance : 396 p. ISBN/ISSN/EAN : 978-3-540-23908-6 Langues : Anglais (eng) Catégories : Thésaurus Agrovoc Changement climatique ; Forêt tropicale humide ; Histoire ; Environnement ; Insolation ; Afrique Liste Plan de classement 634 (changement climatique-effet de serre) [Classement Montpellier] Autres descripteurs Prehistoire Ancienne liste Géo AMERIQUE DU SUD ; ANDES ; AMAZONIE Résumé : 1 . Cretaceous and tertiary climate change and the past distribution of megathermal rainforests. 2 . Andean montane forests and climate change. 3 . Climate change in the lowlands of the amazon basin. 4 . The quaternary history of far eastern rainforests. 5 . Rainforest responses to past climatic changes in tropical Africa. 6 . Tropical environmental dynamics: a modeling perspective. 7 . Prehistoric human occupation and impacts on neotropical forest landscapes during the late pleistocene and early/middle holocene. 8 . Ultraviolet insolation and the tropical rainforest: altitudinal variations, quaternary and recent change, extinctions, and biodiversity. 9 . Climate change and hydrological modes of the wet tropics. 10 . Plant species diversity in Amazonian forests. 11 . Nutrient-cycling and climate change in tropical forests. 12 . The response of south american tropical forests to contemporary atmospheric change. 13 . Ecophysiological response of lowland tropical plants to pleistocene climate. 14 . Modeling future effects of climate change on tropical forests. 15 . Conservation, climate change, and tropical forests. Type de document : Livre Permalien de la notice : https://infodoc.agroparistech.fr/index.php?lvl=notice_display&id=135102 Tropical rainforest responses to climatic change [texte imprimé] / M.B. Bush ; R. Flenley . - Berlin : Springer-Praxis, 2007 . - 396 p. ISBN : 978-3-540-23908-6 Langues : Anglais (eng) Catégories : Thésaurus Agrovoc Changement climatique ; Forêt tropicale humide ; Histoire ; Environnement ; Insolation ; Afrique Liste Plan de classement 634 (changement climatique-effet de serre) [Classement Montpellier] Autres descripteurs Prehistoire Ancienne liste Géo AMERIQUE DU SUD ; ANDES ; AMAZONIE Résumé : 1 . Cretaceous and tertiary climate change and the past distribution of megathermal rainforests. 2 . Andean montane forests and climate change. 3 . Climate change in the lowlands of the amazon basin. 4 . The quaternary history of far eastern rainforests. 5 . Rainforest responses to past climatic changes in tropical Africa. 6 . Tropical environmental dynamics: a modeling perspective. 7 . Prehistoric human occupation and impacts on neotropical forest landscapes during the late pleistocene and early/middle holocene. 8 . Ultraviolet insolation and the tropical rainforest: altitudinal variations, quaternary and recent change, extinctions, and biodiversity. 9 . Climate change and hydrological modes of the wet tropics. 10 . Plant species diversity in Amazonian forests. 11 . Nutrient-cycling and climate change in tropical forests. 12 . The response of south american tropical forests to contemporary atmospheric change. 13 . Ecophysiological response of lowland tropical plants to pleistocene climate. 14 . Modeling future effects of climate change on tropical forests. 15 . Conservation, climate change, and tropical forests. Type de document : Livre Permalien de la notice : https://infodoc.agroparistech.fr/index.php?lvl=notice_display&id=135102

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