Domestication of Amazonian forests

The idea that Amazonian forests have been largely untouched by humans has fascinated naturalists, policy makers, the media, and natural and social scientists worldwide. For many decades, ecological studies overlooked the influence of past peoples in modern forests. However, humans arrived in the Amazon basin at least 13,000 years Before Present (BP) and populations expanded strongly around 2,500 years BP. Evidence of past human activities has been found in extensive areas previously considered pristine. Anthropogenic soils (Amazonian Dark Earths - ADE) and human-made earthworks found across the basin are examples of the landscapes domesticated by pre-Columbian peoples and evidence of large societies with considerable capacity for modifying the environment. Cultivation and management of Amazonian fora by past societies may have significantly contributed to the ecological patterns we see today. These findings stimulated an academic debate about the pristineness versus domestication of Amazonian forests. Although most scientists agree that human impacts were spatially heterogeneous across the basin, the scale of past human influences in Amazonian forests remains controversial. A more realistic and broad- scale view is required (Chapter 1). In my thesis, I integrated data from different disciplines in the social and natural sciences to generate the first broad-scale assessment of the effects of long-term human influences in modern Amazonian forests and how these legacies are maintained by local management practices. I studied the Amazon forest as a mosaic of patches domesticated to different degrees by human-nature interactions. To estimate the influence of past people on modern forests, I first compared the density of sedentary pre-Columbian occupation sites with ADE along some stretches of major white-water rivers and their black or clear-water tributaries that have been sampled by archaeologists. I counted the number of archaeological sites along 12-km sections for both river orders (major and tributary) and found the same density of sites along both orders, showing that archaeological sites are widespread across tributary rivers of the Central Amazon basin (Chapter 2). This result suggests that the influence of past societies in Amazonian landscapes is more extensive than previously imagined and deserves further investigation. To unravel the effects of long-term human actions at the basin-wide scale, we investigated the relationship between the richness and abundance of 85 domesticated plant species found in Amazonian forests and the distribution of known archaeological sites (Chapter 3). We focused on domesticated species because they are known to have been propagated and selected by peoples in Amazonia and elsewhere in the Americas for food or other uses for a long time. I correlated data from more than 1,000 floristic inventories of the Amazon Tree Diversity Network (ATDN) with a map of more than 3,000 archaeological sites across different Amazonian geological regions compiled by the AmazonArch Network. Our analysis also incorporated environmental data to distinguish the relative importance of environmental conditions from past human factors on modern plant communities. We found that domesticated species were five times more likely to be common in floristic inventories than non- domesticated species and sometimes more abundant far from the places where they were domesticated, suggesting past human dispersal. The richness and abundance of these domesticated species increase with the proximity to archaeological sites and in areas with poorly drained soils and higher rainfall seasonality. Our results show that plant communities in Amazonia are structured by both natural and cultural processes, and refute the idea that these forests are largely untouched by humans. To understand the relative contribution of past and recent human activities in shaping these current floristic patterns, we expanded our previous analyses to incorporate the influence of current activities (Chapter 4). We found that old-growth forests were transformed by both past and current peoples, but we showed that the effects of recent activities have a smaller role when compared to the persistent effects of pre-Columbian activities on forest composition. Overall, these new analyses strengthened the importance of ancient peoples in explaining the richness and abundance of domesticated species across Amazonia. In Chapter 5, we investigated how Amazonian people enriched plant communities with useful and domesticated species. To answer this question, we collected extensive information from the literature and data in the field about how Amazonian peoples manage forest resources. With this information, we developed a conceptual model that showed eight key categories of forest management practices that alter natural ecological processes and transform pristine into domesticated forests. Our model allows inferences about how human societies developed ways to interfere with natural ecological processes through time, which created more productive and useful forests across the basin. This long-term process resulted in numerous and diverse patches of useful trees and palms around archaeological sites where humans have lived for centuries or millennia. Thus, a diverse assemblage of useful plant species persists in Amazonian forests due to long-term management practices (Chapters 3-5). In Chapter 6, we compared the effect of ancient and recent management practices on Amazonian forest soils and vegetation at different distances from pre-Columbian and contemporary villages settled in protected areas. We found that soil nutrients of old-growth forests increased with the proximity to ancient villages, but did not increase with the intensity of recent management activities. By enriching soil nutrients in and around their villages, past societies provided the conditions for forests enriched with species of great interest to modern Amazonian societies. Overall, our results support the hypothesis that ancient management practices have a stronger influence in soils of old-growth forests than recent management practices. This thesis reveals the persistence of a cultural heritage in modern Amazonian forests, which was created by ancient societies and maintained by present-day peoples. During the millennia that humans have lived in Amazonia, they interacted with nature, modifying landscapes around their villages into forest mosaics formed by patches rich in fertile anthropogenic soils and forest resources, such as foods, medicines and construction materials. To conclude, Amazonian forests hold legacies of past human activities that can only be fully understood by interdisciplinary studies and that require local management practices to be maintained through time.</p

Pre-Columbian soil fertilization and current management maintain food resource availability in old-growth Amazonian forests

Aims: The extent and persistence of pre-Columbian human legacies in old-growth Amazonian forests are still controversial, partly because modern societies re-occupied old settlements, challenging the distinction between pre- and post-Columbian legacies. Here, we compared the effects of pre-Columbian vs. recent landscape domestication processes on soils and vegetation in two Amazonian regions. Methods: We studied forest landscapes at varying distances from pre-Columbian and current settlements inside protected areas occupied by traditional and indigenous peoples in the lower Tapajós and the upper-middle Madeira river basins. By conducting 69 free-listing interviews, participatory mappings, guided-tours, 27 forest inventories, and soil analysis, we assessed the influences of pre-Columbian and current activities in soils and plant resources surrounding the settlements. Results: In both regions, we found that pre-Columbian villages were more densely distributed across the landscape than current villages. Soil nutrients (mainly Ca and P) were higher closer to pre-Columbian villages but were generally not related to current villages, suggesting past soil fertilization. Soil charcoal was frequent in all forests, suggesting frequent fire events. The density of domesticated plants used for food increased in phosphorus enriched soils. In contrast, the density of plants used for construction decreased near current villages. Conclusions: We detected a significant effect of past soil fertilization on food resources over extensive areas, supporting the hypothesis that pre-Columbian landscape domestication left persistent marks on Amazonian landscapes. Our results suggest that a combination of pre-Columbian phosphorus fertilization with past and current management drives plant resource availability in old-growth forests.</p

Proyecto “Geopolítica del Atlántico Sur. Las relaciones sur-sur y la presencia de las potencias hegemónicas” (2013-2016) : Primer balance de un período cambiante

El presente trabajo es un balance preliminar de los cambios producidos en la geopolítica del espacio en estudio, el océano Atlántico sur y su área de influencia, en los últimos años y la manera en que estas mutaciones actúan sobre nuestras hipótesis de trabajo. El diseño de la geografía política del mundo ha venido cambiando desde los inicios del siglo XXI de una manera inestable y pendular. Frente a un orden unipolar de posguerra fría con hegemonía estadounidense surgieron nuevas potencias emergentes (BRICS) que hoy han sufrido un freno en su crecimiento. El diseño de un nuevo modelo capitalista, estatista y de apariencia más social, contrapuesto al neoliberalismo dominante, ha quedado trunco frente a una nueva andanada de ajustes ligados a las crisis desarrolladas en el primer mundo. Los procesos de integración en América del Sur (MERCOSUR, UNASUR) están siendo relativizados por nuevas elites políticas de derecha, protagonistas de un diálogo de supeditación ligado a los intentos de recuperación hegemónica estadounidense. En África los intentos de crecimiento e integración, acompañados de las propuestas de cooperación sur-sur de los emergentes, hoy están supeditadas a las políticas diseñadas desde centros militares dedicados a una supuesta lucha contra el yihadismo. En el medio, el Atlántico sur se ve envuelto en renovadas políticas armamentistas a escala mundial y en los intereses económicos extractivistas de las grandes corporaciones a las cuales se asocian las nuevas elites locales. Los intereses comerciales vuelven a volcarse a favor del Pacífico y del Atlántico norte y del Pacífico. Este primer balance implica la realización de un ajuste temático y teórico para un nuevo proyecto que pueda incluir estas nuevas realidades y otros temas y regiones de interés.Facultad de Humanidades y Ciencias de la Educació

Proyecto “Geopolítica del Atlántico Sur. Las relaciones sur-sur y la presencia de las potencias hegemónicas” (2013-2016) : Primer balance de un período cambiante

El presente trabajo es un balance preliminar de los cambios producidos en la geopolítica del espacio en estudio, el océano Atlántico sur y su área de influencia, en los últimos años y la manera en que estas mutaciones actúan sobre nuestras hipótesis de trabajo. El diseño de la geografía política del mundo ha venido cambiando desde los inicios del siglo XXI de una manera inestable y pendular. Frente a un orden unipolar de posguerra fría con hegemonía estadounidense surgieron nuevas potencias emergentes (BRICS) que hoy han sufrido un freno en su crecimiento. El diseño de un nuevo modelo capitalista, estatista y de apariencia más social, contrapuesto al neoliberalismo dominante, ha quedado trunco frente a una nueva andanada de ajustes ligados a las crisis desarrolladas en el primer mundo. Los procesos de integración en América del Sur (MERCOSUR, UNASUR) están siendo relativizados por nuevas elites políticas de derecha, protagonistas de un diálogo de supeditación ligado a los intentos de recuperación hegemónica estadounidense. En África los intentos de crecimiento e integración, acompañados de las propuestas de cooperación sur-sur de los emergentes, hoy están supeditadas a las políticas diseñadas desde centros militares dedicados a una supuesta lucha contra el yihadismo. En el medio, el Atlántico sur se ve envuelto en renovadas políticas armamentistas a escala mundial y en los intereses económicos extractivistas de las grandes corporaciones a las cuales se asocian las nuevas elites locales. Los intereses comerciales vuelven a volcarse a favor del Pacífico y del Atlántico norte y del Pacífico. Este primer balance implica la realización de un ajuste temático y teórico para un nuevo proyecto que pueda incluir estas nuevas realidades y otros temas y regiones de interés.Facultad de Humanidades y Ciencias de la Educació

Proyecto “Geopolítica del Atlántico Sur. Las relaciones sur-sur y la presencia de las potencias hegemónicas” (2013-2016) : Primer balance de un período cambiante

El presente trabajo es un balance preliminar de los cambios producidos en la geopolítica del espacio en estudio, el océano Atlántico sur y su área de influencia, en los últimos años y la manera en que estas mutaciones actúan sobre nuestras hipótesis de trabajo. El diseño de la geografía política del mundo ha venido cambiando desde los inicios del siglo XXI de una manera inestable y pendular. Frente a un orden unipolar de posguerra fría con hegemonía estadounidense surgieron nuevas potencias emergentes (BRICS) que hoy han sufrido un freno en su crecimiento. El diseño de un nuevo modelo capitalista, estatista y de apariencia más social, contrapuesto al neoliberalismo dominante, ha quedado trunco frente a una nueva andanada de ajustes ligados a las crisis desarrolladas en el primer mundo. Los procesos de integración en América del Sur (MERCOSUR, UNASUR) están siendo relativizados por nuevas elites políticas de derecha, protagonistas de un diálogo de supeditación ligado a los intentos de recuperación hegemónica estadounidense. En África los intentos de crecimiento e integración, acompañados de las propuestas de cooperación sur-sur de los emergentes, hoy están supeditadas a las políticas diseñadas desde centros militares dedicados a una supuesta lucha contra el yihadismo. En el medio, el Atlántico sur se ve envuelto en renovadas políticas armamentistas a escala mundial y en los intereses económicos extractivistas de las grandes corporaciones a las cuales se asocian las nuevas elites locales. Los intereses comerciales vuelven a volcarse a favor del Pacífico y del Atlántico norte y del Pacífico. Este primer balance implica la realización de un ajuste temático y teórico para un nuevo proyecto que pueda incluir estas nuevas realidades y otros temas y regiones de interés.Facultad de Humanidades y Ciencias de la Educació

Junín Virus Infection of Human Hematopoietic Progenitors Impairs In Vitro Proplatelet Formation and Platelet Release via a Bystander Effect Involving Type I IFN Signaling

Argentine hemorrhagic fever (AHF) is an endemo-epidemic disease caused by Junín virus (JUNV), a member of the arenaviridae family. Although a recently introduced live attenuated vaccine has proven to be effective, AHF remains a potentially lethal infection. Like in other viral hemorrhagic fevers (VHF), AHF patients present with fever and hemorrhagic complications. Although the causes of the bleeding are poorly understood, impaired hemostasis, endothelial cell dysfunction and low platelet counts have been described. Thrombocytopenia is a common feature in VHF syndromes, and it is a major sign for its diagnosis. However, the underlying pathogenic mechanism has not yet been elucidated. We hypothesized that thrombocytopenia results from a viral-triggered alteration of the megakaryo/thrombopoiesis process. Therefore, we evaluated the impact of JUNV on megakaryopoiesis using an in vitro model of human CD34+ cells stimulated with thrombopoietin. Our results showed that CD34+ cells are infected with JUNV in a restricted fashion. Infection was transferrin receptor 1 (TfR1)-dependent and the surface expression of TfR1 was higher in infected cultures, suggesting a novel arenaviral dissemination strategy in hematopoietic progenitor cells. Although proliferation, survival, and commitment in JUNV-infected cultures were normal, viral infection impaired thrombopoiesis by decreasing in vitro proplatelet formation, platelet release, and P-selectin externalization via a bystander effect. The decrease in platelet release was also TfR1-dependent, mimicked by poly(I:C), and type I interferon (IFN α/β) was implicated as a key paracrine mediator. Among the relevant molecules studied, only the transcription factor NF-E2 showed a moderate decrease in expression in megakaryocytes from either infected cultures or after type I IFN treatment. Moreover, type I IFN-treated megakaryocytes presented ultrastructural abnormalities resembling the reported thrombocytopenic NF-E2−/− mouse phenotype. Our study introduces a potential mechanism for thrombocytopenia in VHF and other diseases associated with increased bone marrow type I IFN levels

Critical transitions in the Amazon forest system

The possibility that the Amazon forest system could soon reach a tipping point, inducing large-scale collapse, has raised global concern1-3. For 65 million years, Amazonian forests remained relatively resilient to climatic variability. Now, the region is increasingly exposed to unprecedented stress from warming temperatures, extreme droughts, deforestation and fires, even in central and remote parts of the system1. Long existing feedbacks between the forest and environmental conditions are being replaced by novel feedbacks that modify ecosystem resilience, increasing the risk of critical transition. Here we analyse existing evidence for five major drivers of water stress on Amazonian forests, as well as potential critical thresholds of those drivers that, if crossed, could trigger local, regional or even biome-wide forest collapse. By combining spatial information on various disturbances, we estimate that by 2050, 10% to 47% of Amazonian forests will be exposed to compounding disturbances that may trigger unexpected ecosystem transitions and potentially exacerbate regional climate change. Using examples of disturbed forests across the Amazon, we identify the three most plausible ecosystem trajectories, involving different feedbacks and environmental conditions. We discuss how the inherent complexity of the Amazon adds uncertainty about future dynamics, but also reveals opportunities for action. Keeping the Amazon forest resilient in the Anthropocene will depend on a combination of local efforts to end deforestation and degradation and to expand restoration, with global efforts to stop greenhouse gas emissions

Hyperdominance in Amazonian Forest Carbon Cycling

While Amazonian forests are extraordinarily diverse, the abundance of trees is skewed strongly towards relatively few ‘hyperdominant’ species. In addition to their diversity, Amazonian trees are a key component of the global carbon cycle, assimilating and storing more carbon than any other ecosystem on Earth. Here we ask, using a unique data set of 530 forest plots, if the functions of storing and producing woody carbon are concentrated in a small number of tree species, whether the most abundant species also dominate carbon cycling, and whether dominant species are characterized by specific functional traits. We find that dominance of forest function is even more concentrated in a few species than is dominance of tree abundance, with only ≈1% of Amazon tree species responsible for 50% of carbon storage and productivity. Although those species that contribute most to biomass and productivity are often abundant, species maximum size is also influential, while the identity and ranking of dominant species varies by function and by region

Estimating the global conservation status of more than 15,000 Amazonian tree species

Estimates of extinction risk for Amazonian plant and animal species are rare and not often incorporated into land-use policy and conservation planning. We overlay spatial distribution models with historical and projected deforestation to show that at least 36% and up to 57% of all Amazonian tree species are likely to qualify as globally threatened under International Union for Conservation of Nature (IUCN) Red List criteria. If confirmed, these results would increase the number of threatened plant species on Earth by 22%. We show that the trends observed in Amazonia apply to trees throughout the tropics, and we predict thatmost of the world’s >40,000 tropical tree species now qualify as globally threatened. A gap analysis suggests that existing Amazonian protected areas and indigenous territories will protect viable populations of most threatened species if these areas suffer no further degradation, highlighting the key roles that protected areas, indigenous peoples, and improved governance can play in preventing large-scale extinctions in the tropics in this century