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The legacy of 4,500 years of polyculture agroforestry in the eastern Amazon

  • Max Planck Institute for Geoanthropology
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The legacy of pre-Columbian land use on modern Amazonian forests has stimulated considerable debate which, until now, has not been satisfactorily resolved due to the absence of integrated studies between pre-Columbian and modern land use. Here we show an abrupt enrichment of edible forest species combined with the cultivation of multiple annual crops in lake and terrestrial fossil records associated with pre-Columbian occupation in the eastern Amazon. Our results suggest that ~4,500 years ago, pre-Columbians adopted a polyculture agroforestry subsistence strategy that intensified with the development of Amazon Dark Earth soils after ~2,000 cal yr B.P. These millennial-scale polyculture agroforestry systems have left an enduring legacy on the modern enrichment of edible plants, demonstrating the important role of past indigenous land management in shaping modern forest ecosystems in the eastern Amazon.
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1Department of Archaeology, College of Humanities, University of Exeter, Exeter, UK. 2Programa de Pós-Graduação em Ecologia, Instituto Nacional de
Pesquisas da Amazônia (INPA), Manaus, Brazil. 3Forest Ecology and Management Group, Wageningen University & Research, Wageningen,
The Netherlands. 4Department of Geography, College of Life and Environmental Sciences, University of Exeter, Exeter, UK. 5Universidade do Estado
de Mato Grosso, Campus of Nova Xavantina, Mato Grosso State, Brazil. 6Department of Anthropology, Federal University of Pará, Belém, Brazil.
The legacy of pre-Columbian land use in the Amazonian rain-
forest is one of the most controversial topics in the social110 and
natural sciences11,12. Until now, the debate has been limited to
discipline-specific studies, based purely on archaeological
data8, modern vegetation13, modern ethnographic data3 or a
limited integration of archaeological and palaeoecological
data12. The lack of integrated studies to connect past land use
with modern vegetation has left questions about the legacy
of pre-Columbian land use on the modern vegetation compo-
sition in the Amazon, unanswered11. Here, we show that per-
sistent anthropogenic landscapes for the past 4,500 years
have had an enduring legacy on the hyperdominance of edible
plants in modern forests in the eastern Amazon. We found an
abrupt enrichment of edible plant species in fossil lake and
terrestrial records associated with pre-Columbian occupa-
tion. Our results demonstrate that, through closed-canopy
forest enrichment, limited clearing for crop cultivation and
low-severity fire management, long-term food security was
attained despite climate and social changes. Our results sug-
gest that, in the eastern Amazon, the subsistence basis for
the development of complex societies began ~4,500 years
ago with the adoption of polyculture agroforestry, combining
the cultivation of multiple annual crops with the progressive
enrichment of edible forest species and the exploitation of
aquatic resources. This subsistence strategy intensified with
the later development of Amazonian dark earths, enabling the
expansion of maize cultivation to the Belterra Plateau, provid-
ing a food production system that sustained growing human
populations in the eastern Amazon. Furthermore, these mil-
lennial-scale polyculture agroforestry systems have an endur-
ing legacy on the hyperdominance of edible plants in modern
forests in the eastern Amazon. Together, our data provide a
long-term example of past anthropogenic land use that can
inform management and conservation efforts in modern
Amazonian ecosystems.
The extent to which pre-Columbian societies altered Amazonian
landscapes is one of the most debated topics in botany3,11,1315,
archaeology1,2,57, palaeoecology7,12,1619 and conservation4,20,21. New
findings show that a disproportionate number of plants, accounting
for half of all trees in the Amazon, are hyperdominant22 and domes-
ticated species are five-times more likely to be hyperdominant than
non-domesticated species13. This is particularly prevalent in archae-
ological sites, suggesting that the effect of pre-Columbian people
on modern flora is more pronounced than previously thought13.
The pre-Columbian anthropogenic soils, known as Amazonian
dark earths (ADEs; traditionally called Terras Pretas de Índio), are
one of the most distinct lines of evidence of human transforma-
tion of Amazonia because these modified soils are indicators of
pre-Columbian sedentary occupation23,24. ADEs have been associ-
ated with sustained and intensive agriculture in the past and have
been re-utilized by modern farmers because of their extremely high
fertility4. Several studies have shown that (1) forests on ADEs have
a distinct species composition, exhibiting greater richness and a
higher abundance of domesticated and edible plants (used as food
resources)25, (2) the more complex the ADE archaeological context
(for example, multicomponent sites), the greater the floristic com-
position of cultivated useful plants in modern home gardens26, and
(3) increased fertility associated with ADEs improves conditions
for the establishment and growth of exotic species that are gener-
ally more nutrient demanding than native Amazonian species27.
However, the lack of detailed integrated archaeological or palaeo-
ecological studies to connect past land use with modern vegetation
have left fundamental questions about land-use practices and the
effect of ADEs on modern Amazonian ecosystems unresolved. To
address these issues, we integrate archaeology and archaeobotany
records that reflect local-scale vegetation histories with lake and
terrestrial palaeoecology that reflects broader regional-scale vegeta-
tion histories, combined with palaeoclimate and modern botanical
surveys to investigate the impact of the past 4,500 years of human
land use in the eastern Amazon (Fig. 1).
The study area located within the protected rainforest of the
FLONA Tapajós Reserve, provides an ideal setting because of the
presence of extensive archaeological sites, high concentrations of
ADE soils, a nearby lake with limited riverine influence and the
existence of a nearby high-resolution palaeoclimate record28. We
(1) collected a 210-cm sediment core dating to ~8,500 calendar
years (cal)  from Lake Caranã (~0.7 km in diameter, ~3 m in
depth; 2° 50 08 S, 55° 02 33 W; 5 m above sea level) for palaeo-
ecological analysis (see Methods section ‘Regional study area’ to
‘Pollen’); (2) carried out excavations and sampled three ADE soil
profiles at the nearby Serra do Maguari-1 (SDM1) archaeologi-
cal site (see Methods sections ‘Archaeological site selection’ and
‘Soil phytoliths’), ~5 km northeast of Lake Caranã on the crest of
the upper slope of the Belterra Plateau (2° 47 87 S, 55° 03 53 W;
126 m above sea level) (Supplementary Fig. 4), compiled exist-
ing regional archaeological data (see Methods (the ‘SPDs and site
The legacy of 4,500 years of polyculture
agroforestry in the eastern Amazon
S. Yoshi Maezumi  1*, Daiana Alves1, Mark Robinson1, Jonas Gregorio de Souza  1, Carolina Levis2,3,
Robert L. Barnett4, Edemar Almeida de Oliveira5, Dunia Urrego  4, Denise Schaan6 and José Iriarte  1
NATURE PLANTS | VOL 4 | AUGUST 2018 | 540–547 |
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... Esculenta), pineapple (Ananas comosus), rice (Oryza sp.) and peach palm (Bactris gasipaes) [5][6][7]. Meanwhile, studies have tracked the arrival of maize (Zea mays) from North and Central America into the region, and its integration into swidden cultivation strategies [8,9]. Not only that, but there is evidence for the active management of freshwater resources [10], the movement and arboriculture of tree species such as the Brazil Nut (Bertholletia excelsa) [11], and burning to manage ecological structure and dynamics [12]. ...
... Not only that, but there is evidence for the active management of freshwater resources [10], the movement and arboriculture of tree species such as the Brazil Nut (Bertholletia excelsa) [11], and burning to manage ecological structure and dynamics [12]. Pre-colonial Indigenous impacts are now known to have been so significant that they led to the widespread formation of Anthropogenic Dark Earth (ADE) soils and a lasting legacy on the species composition of tropical forests across the Amazon Basin that are still visible in the 21 st century [9,13,14]. Furthermore, mixed cultivation, fishing, and arboriculture seem to have sustained populations of up to 8-20 million at the time of European arrival [1,15], and urban networks [16], earthworks [17], and other forms of landscape modification [10] have been documented across the basin. Nevertheless, while the Amazon Basin has now been established as a key center of past human settlement and cultivation [15,[18][19][20][21], regional, multidisciplinary studies highlighting subsistence complexity are rare. ...
... However, detailed local studies have also highlighted human subsistence reliance on domesticated root crops such as manioc and non-domesticated plants and animals, including aquatic resources (e.g. [9,24]). Indeed, given the vast area (7,500,000 km 2 ) of the Amazon Basin and its forests, spanning eight countries, and a variety of different ecological zones, it is essential to develop more nuanced, contextual insights into variations in settlement distribution, geography, and human subsistence adaptations. ...
Full-text available
Although once considered a ‘counterfeit paradise’, the Amazon Basin is now a region of increasing interest in discussions of pre-colonial tropical land-use and social complexity. Archaeobotany, archaeozoology, remote sensing and palaeoecology have revealed that, by the Late Holocene, populations in different parts of the Amazon Basin were using various domesticated plants, modifying soils, building earthworks, and even forming ‘Garden Cities’ along the Amazon River and its tributaries. However, there remains a relatively limited understanding as to how diets, environmental management, and social structures varied across this vast area. Here, we apply stable isotope analysis to human remains (n = 4 for collagen, n = 17 for tooth enamel), and associated fauna (n = 61 for collagen, n = 28 for tooth enamel), to directly determine the diets of populations living in the Volta Grande do Rio Xingu, an important region of pre-Columbian cultural interactions, between 390 cal. years BC and 1,675 cal. years AD. Our results highlight an ongoing dietary focus on C 3 plants and wild terrestrial fauna and aquatic resources across sites and time periods, with varying integration of C 4 plants (i.e. maize). We argue that, when compared to other datasets now available from elsewhere in the Amazon Basin, our study highlights the development of regional adaptations to local watercourses and forest types.
... 5. The Amazon was increasingly recognized as a "socio-environment" constructed through people's historical geo-biotic transformations of forests and soils, and engineering works, based on archeological, ethnographic, and historical research (Balée 1998;Fausto and Heckenberger 2007;Heckenberger et al. 2007;Parssinen et al. 2009;Clement et al. 2015;Athayde et al. 2017;Watling et 14.15 al. 2017;de Souza et al. 2018;Levis et al. 2018;Maezumi et al. 2018). These were analyzed with current enthographies and provide an alternative source of technologies for longer term ecosystem and social resilience in the current moment, and a kind of epistemological bridge to the future. ...
... During the 1988 Brazilian Constitutional Convention, the articulation of inhabited landscapes as conservation spaces and the idea of forest peoples as forest guardians and defenders gained salience, and were incorporated into land laws and the creation of legislative frameworks and institutional development for agro-extractivist reserves, sustainable development settlements, historical communities and their territorial claims, and better recognition of Indigenous land rights. Indigenous people and local communities successfully pushed for conservation approaches, laws, and institutions that recognized the important role of historical Amazonian populations in both creating the Amazon's ecological complexity as well as in protecting forested landscapes (Balée and Erickson 2006;Nepstad et al. 2006;Vogt et al. 2015;Levis et al. 2018;Maezumi et al. 2018;Brondizio et al. 2021). New ways of thinking about the role of Amazonian forests focused on global and regional climate dynamics, environmental services, expanded ecological economics, recognition of the rights of nature, and concerns over environmental justice (Conklin and Graham 1995;Nogueira et al. 2018). ...
... Their systems integrate both local communities and modern knowledge to manage, produce and conserve plants, animals (including fish) and other biological resources (Thomas et al. 2017;Sears et al. 2007). Their flexibility, resilience, and linkages among extraction, conservation and production, have greatly facilitated the process of production of valuable terrestrial and aquatic resources and domestication of landscapes, and the use and management of a range of semi-domesticated species (Coomes et al. 2020;Franco et al. 2021;Levis 2018;Levis et al. 2018;Maezumi et al. 2018;Vogt et al. 2016;Erickson 2006: see also Chapters 8, 10 and 13). The flexibility and complexity of linked systems highlight the diversity found among family-based agroforestry and fisheries production systems explored here. ...
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This Report provides a comprehensive, objective, open, transparent, systematic, and rigorous scientific assessment of the state of the Amazon’s ecosystems, current trends, and their implications for the long-term well-being of the region, as well as opportunities and policy relevant options for conservation and sustainable development.
... Persistent Indigenous legacies from cultural burning have been demonstrated elsewhere in Amazon rainforest ecosystems [16,20,60,61]; however, it is unclear how past humanenvironment interactions may have shaped transitional ecosystems associated with the ARE. To explore the influence of the past 6000 years of climate, human land use, and cultural burning on ARE ecosystems in the Bolivian Amazon, we implemented a multi-proxy approach [62][63][64] to compare local-scale land use, vegetation and fire histories (archaeological excavations/terrestrial archaeobotany) with broader regional-scale vegetation histories (lake palaeoecology). These data are contextualized with existing regional archaeological evidence documenting human occupation and plant domestication in the region as early as 10 500 cal yr BP [2,3,5]. ...
... Three soil test pits were excavated along the transect for archaeobotanical, geochemical and isotopic sampling representing ADE, ABE and nearby ferralsol soils used as control sample [76]. Archaeobotanical analysis of the samples ( phytoliths and macrocharcoal) was conducted following standard procedures [64,76]. Full archaeobotanical analysis is presented elsewhere [5,76], with key results being discussed below. ...
... This interpretation is consistent with extensive ethnographic and archaeological evidence documenting the use of frequent burning as a tool to clear land for crop cultivation and increase soil fertility for nutrient-demanding crops such as maize [38,112,113]. The occurrence of maize pollen at LV after ca 5700 cal yr BP is consistent with a temporal gradient of maize dispersal that begins outside Amazonia and reaches the ARE after 7000 cal yr BP [64,104,110,[114][115][116]. Earliest maize in the region appears ca 6850 cal yr BP in anthropic forest islands of the seasonally flooded savannahs to the southwest of Triunfo [3], Lake Rogaguado ca 6500 cal yr BP [104] and in the nearby Monte Castelo shell-mound ca 5300 cal yr BP [4,117]. ...
The southwestern Amazon Rainforest Ecotone (ARE) is the transitional landscape between the tropical forest and seasonally flooded savannahs of the Bolivian Llanos de Moxos. These heterogeneous landscapes harbour high levels of biodiversity and some of the earliest records of human occupation and plant domestication in Amazonia. While persistent Indigenous legacies have been demonstrated elsewhere in the Amazon, it is unclear how past human–environment interactions may have shaped vegetation composition and structure in the ARE. Here, we examine 6000 years of archaeological and palaeoecological data from Laguna Versalles (LV), Bolivia. LV was dominated by stable rainforest vegetation throughout the Holocene. Maize cultivation and cultural burning are present after ca 5700 cal yr BP. Polyculture cultivation of maize, manioc and leren after ca 3400 cal yr BP predates the formation of Amazonian Dark/Brown Earth (ADE/ABE) soils (approx. 2400 cal yr BP). ADE/ABE formation is associated with agroforestry indicated by increased edible palms, including Mauritia flexuosa and Attalea sp., and record levels of burning, suggesting that fire played an important role in agroforestry practices. The frequent use of fire altered ADE/ABD forest composition and structure by controlling ignitions, decreasing fuel loads and increasing the abundance of plants preferred by humans. Cultural burning and polyculture agroforestry provided a stable subsistence strategy that persisted despite pronounced climate change and cultural transformations and has an enduring legacy in ADE/ABE forests in the ARE. This article is part of the theme issue ‘Tropical forests in the deep human past’.
... maize (Zea), manioc, sweet potato (Ipomoea)) or species that are useful for humans (e.g. soursop (Annona), buriti palm, cocoa (Theobroma)) [27,40,41] in lake sediment records can also be used to reconstruct temporal patterns of cultivation [42][43][44] or of forest enrichment [45]. These indicators of human activity are often assessed alongside other pollen types to infer the effect of human activity on the vegetation surrounding and near the lake, including characteristics such as forest openness, or disturbance [38,39,46,47]. ...
... Successional regrowth is commonly indicated by increases in the pollen abundances of Cecropia, a fast-growing pioneer species that typically colonizes disturbed and abandoned areas [49][50][51][52]. Lake sedimentary records collected adjacent to archaeological sites are also beginning to be used to provide temporally continuous reconstructions of human influences on these settings [15,45,[53][54][55]. ...
... step-increase in charcoal concentration) rather than presence, or other types of evidence that are widespread only over the late Holocene (e.g. cultivars or earthworks) [10,16,24,45,79,[117][118][119][120][121][122], almost certainly underestimates the earliest human presence in these sites. ...
Humans have been present in Amazonia throughout the Holocene, with the earliest archaeological sites dating to 12 000 years ago. The earliest inhabitants began managing landscapes through fire and plant domestication, but the total extent of vegetation modification remains relatively unknown. Here, we compile palaeoecological records from lake sediments containing charcoal and from pollen analyses to understand how human land-use affected vegetation during the early to mid-Holocene, and place our results in the context of previous archaeological work. We identified gradual, rather than abrupt changes in forest openness, disturbance and enrichment, with useful species at almost all sites. Early human occupations occurred in peripheral sites of Amazonia, where natural fires are part of the vegetation dynamics, so human-made fires did not exert a novel form of disturbance. Synchronicity between evidence of the onset of human occupation in lake records and archaeological sites was found for eastern Amazonia. For southwestern and western Amazonia and the Guiana Shield, the timing of the onset of human occupation differed by thousands of years between lake records and archaeological sites. Plant cultivation showed a different spatio-temporal pattern, appearing ca 2000 years earlier in western Amazonia than in other regions. Our findings highlight the spatial–temporal heterogeneity of Amazonia and indicate that the region cannot be treated as one entity when assessing ecological or cultural history. This article is part of the theme issue ‘Tropical forests in the deep human past’.
... Early human populations in the Americas have traditionally been portrayed as mobile hunter-gatherers who exploited coastal resources and large savannah game, while avoiding forest habitats as a result of the absence of large mammals and the difficulties of mobility in dense forest vegetation [73][74][75]. Contrary to this classic paradigm, mounting evidence suggests early colonists were actively exploiting and managing trees of economic importance and quite quickly began practicing early cultivation of annual crops [76][77][78][79][80][81][82][83]. These data have important implications for understanding plant domestication, the long-term legacy of human-plant interactions and the potential role of humans in the current hyperdominance of useful plants in Amazonia [22,84,85]. ...
... Resolving the role of tropical forests in the deep human past is clearly a truly interdisciplinary endeavour, often involving 'an archaeology of the invisible'. For example, traces of human activities may be found in the current distributions and community composition of wild plants and trees (such as palm nuts in the Congo Basin and brazil nuts in the Amazon Basin), in patterns of charcoal accumulation [93] and in alterations of soil composition in palaeoenvironmental cores and archaeological sites [83], and faunal communities [39] (figure 2). The study of the growth rings of living trees (dendrochronology) has even been shown to track human management of forests in more recent periods [94]. ...
Full-text available
Since Darwin, studies of human evolution have tended to give primacy to open ‘savannah’ environments as the ecological cradle of our lineage, with dense tropical forests cast as hostile, unfavourable frontiers. These perceptions continue to shape both the geographical context of fieldwork as well as dominant narratives concerning hominin evolution. This paradigm persists despite new, ground-breaking research highlighting the role of tropical forests in the human story. For example, novel research in Africa's rainforests has uncovered archaeological sites dating back into the Pleistocene; genetic studies have revealed very deep human roots in Central and West Africa and in the tropics of Asia and the Pacific; an unprecedented number of coexistent hominin species have now been documented, including Homo erectus , the ‘Hobbit’ ( Homo floresiensis ), Homo luzonensis , Denisovans, and Homo sapiens . Some of the earliest members of our own species to reach South Asia, Southeast Asia, Oceania and the tropical Americas have shown an unexpected rapidity in their adaptation to even some of the more ‘extreme’ tropical settings. This includes the early human manipulation of species and even habitats. This volume builds on these currently disparate threads and, for the first time, draws together a group of interdisciplinary, agenda-setting papers that firmly places a broader spectrum of tropical environments at the heart of the deep human past. This article is part of the theme issue ‘Tropical forests in the deep human past’.
... This could be because the change to fenced free grazing is recent (30-10 years) compared to millennia-old traditional herding (Molinier and Tallon, 1950;Tatin et al., 2013). It is well established that current ecological factors alone cannot explain current vegetation community composition and structure, and land-use legacies have already been found in several ecosystems (Cuddington, 2011;Karlík and Poschlod, 2014;Maezumi et al., 2018). Moreover, historical dynamics are also known to affect soil properties (Dambrine et al., 2007;Elgersma et al., 2011). ...
Grazing is well-known to shape plant populations and plant communities and to affect several compartment characteristics of grazed ecosystems. Semi-natural grassland conservation depends on the maintenance of traditional extensive grazing systems which can exist for centuries, even millennia. However, very few studies have concomitantly investigated the effect of grazing management on plant, forage, litter and soil compartments and the implications of their potential interactions for conservation after recent changes in grazing practices. This study thus aimed to identify the concomitant effects of sheep grazing on the latter compartments of Mediterranean grasslands. We further investigated the effects of a recent change from millenia-old traditional herding to contemporary fenced free grazing. We also sought to determine how this change may impact the agronomic and ecological value of these grasslands. Surveys were carried out at 6 different study sites paired by the two different grazing practices in a French Mediterranean sub-steppic vegetation (“Crau” plain in Southeastern France). Using linear models and distance-based redundancy analysis, effects of grazing intensity, grazing practices and their interactions were tested on plant community, forage, litter and soil physicochemical properties. Our results show that, there was a significant effect of grazing intensity on the four studied compartments, with significantly higher species richness and evenness at moderate grazing intensity. Biomass was also significantly higher at moderate grazing intensity. Digestibility of forage, litter quality and soil fertility decreased significantly under less intensive grazing. Significant differences were also found in the relative size of the areas covered by each plant communities. Recent fenced free grazing led to significantly more intensively grazed zones, with more mesophilous/nitrophilous vegetation. Conversely, in zones traditionally less intensively grazed, the contemporary free grazing led to higher plant species-richness but again with more mesophilous species. Implications for conservation management are that the legacy of millennia-old traditional herding still compensates partly for the effects of changing practice to contemporary fenced free grazing on plant community composition but not on their relative sizes. This indicates an increase in grazing intensity in the remotest zone which could lead to grassland plant community homogenization.
... Tropical agroforestry landscapes are typical social-ecological systems that have existed for centuries or even millennia -especially those located in the biodiversity hotspots exemplify traditional practices and lessons for the future (e.g. Maezumi et al. 2018;Kulkarni et al. 2021). The Western Ghats, a 1600-km mountain range running parallel to the west coast of India, is one such biodiversity hotspot where tropical rainforests support the highest human population density. ...
Full-text available
Building science–policy interfaces is essential for envisioning pragmatic environmental solutions. Drawing from the Western Ghats of India, we identify mutual areas of interest, or "commons", where specific environmental management issues can benefit from a long-term perspective, encouraging paleoscience–policy connections.
... Thus, some modern humid montane forests could have been completely cleared or modified as recently as 500-350 years ago. As such, the legacy of past forest disturbance expressed in successional change may still be influencing forest structure and composition, species abundances and carbon sequestration [23][24][25]. ...
Much has yet to be learned of the spatial patterning of pre-Columbian people across the Tropical Andes. Using compiled archaeological data and a suite of environmental variables, we generate an ensemble species distribution model (SDM) that incorporates general additive models, random forest models and Maxent models to reconstruct spatial patterns of pre-Columbian people that inhabited the Tropical Andes east of the continental divide, within the modern countries of Bolivia, Peru and Ecuador. Within this region, here referred to as the eastern Andean flank, elevation, mean annual cloud frequency, distance to rivers and precipitation of the driest quarter are the environmental variables most closely related to human occupancy. Our model indicates that 11.04% of our study area (65 368 km ² ) was likely occupied by pre-Columbian people. Our model shows that 30 of 351 forest inventory plots, which are used to generate ecological understanding of Andean ecosystems, were likely occupied in the pre-Columbian period. In previously occupied sites, successional trajectories may still be shaping forest dynamics, and those forests may still be recovering from the ecological legacy of pre-Columbian impacts. Our ensemble SDM links palaeo- and neo-ecology and can also be used to guide both future archaeological and ecological studies. This article is part of the theme issue ‘Tropical forests in the deep human past’.
The Amazon, which is the largest rainforest on Earth, has significant implications for both regional and global weather and climate. The recent fires and environmental degradation in combination with a changing climate already have and will continue to have major effects on the forest. A home to nearly a third of the world's biodiversity, the Amazon is the greatest expression of life on Earth, yet it is under attack. The Amazon rainforest is not evolutionarily adapted to seasonal fire, thus the rapid expansion of the human frontier with fire has been devastating. The siege on the rainforest through fire for agricultural purposes has gradually eroded the natural defenses of the rainforest against fires and driven the Amazon toward a tipping point. In most cases, these fires are purposely started to drive indigenous peoples from their land, and in combination with the increasing average surface temperatures engendered by climate change, tropical fires are more likely to be more extensive. In turn, fires release massive amounts of carbon dioxide and diminish the carbon sequestering capacity of tropical forests, contributing to GHG emissions that cause climate change. The literature we review suggests that this will only exacerbate the weather and climate extremes that impact not only the Amazon, but our entire planet. With the erosion of the rainforest has come a parallel erosion of indigenous land rights and violations of human rights. These complex factors involved in the degradation of the Amazon warrant a scientific, political, economic, and cultural approach.
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Humans have influenced global fire activity for millennia and will continue to do so into the future. Given the long-term interaction between humans and fire, we propose a collaborative research agenda linking archaeology and fire science that emphasizes the socioecological histories and consequences of anthropogenic fire in the development of fire management strategies today.
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The discovery of large geometrical earthworks in interfluvial settings of southern Amazonia has challenged the idea that Pre-Columbian populations were concentrated along the major floodplains. However, a spatial gap in the archaeological record of the Amazon has limited the assessment of the territorial extent of earth-builders. Here, we report the discovery of Pre-Columbian ditched enclosures in the Tapajós headwaters. The results show that an 1800 km stretch of southern Amazonia was occupied by earth-building cultures living in fortified villages ~Cal AD 1250–1500. We model earthwork distribution in this broad region using recorded sites, with environmental and terrain variables as predictors, estimating that earthworks will be found over ~400,000 km2 of southern Amazonia. We conclude that the interfluves and minor tributaries of southern Amazonia sustained high population densities, calling for a re-evaluation of the role of this region for Pre-Columbian cultural developments and environmental impact.
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For millennia, Amazonian peoples have managed forest resources, modifying the natural environment in subtle and persistent ways. Legacies of past human occupation are striking near archaeological sites, yet we still lack a clear picture of how human management practices resulted in the domestication of Amazonian forests. The general view is that domesticated forests are recognizable by the presence of forest patches dominated by one or a few useful species favored by long-term human activities. Here, we used three complementary approaches to understand the long-term domestication of Amazonian forests. First, we compiled information from the literature about how indigenous and traditional Amazonian peoples manage forest resources to promote useful plant species that are mainly used as food resources. Then, we developed an interdisciplinary conceptual model of how interactions between these management practices across space and time may form domesticated forests. Finally, we collected field data from 30 contemporary villages located on and near archaeological sites, along four major Amazonian rivers, to compare with the management practices synthesized in our conceptual model. We identified eight distinct categories of management practices that contribute to form forest patches of useful plants: (1) removal of non-useful plants, (2) protection of useful plants, (3) attraction of non-human animal dispersers, (4) transportation of useful plants, (5) selection of phenotypes, (6) fire management, (7) planting of useful plants, and (8) soil improvement. Our conceptual model, when ethnographically projected into the past, reveals how the interaction of these multiple management practices interferes with natural ecological processes, resulting in the domestication of Amazonian forest patches dominated by useful species. Our model suggests that management practices became more frequent as human population increased during the Holocene. In the field, we found that useful perennial plants occur in multi-species patches around archaeological sites, and that the dominant species are still managed by local people, suggesting long-term persistence of ancient cultural practices. The management practices we identified have transformed plant species abundance and floristic composition through the creation of diverse forest patches rich in edible perennial plants that enhanced food production and food security in Amazonia.
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A 50,000-year-old sediment core record from Laguna Chaplin is reanalyzed to explore potential paleoecological methods to detect the extent of pre-Columbian disturbance in the Bolivian Amazon. High-resolution (sub-centennial) macrocharcoal data are analyzed using statistical algorithm software including Regime Shift Detection and CHAR Analysis to detect changes in past fire regimes. These data are compared with existing charcoal records from throughout the Bolivian lowlands to provide a regional scale context of past biomass burning. During the mid-Holocene, changes in precipitation are the dominant driver of fire activity and biomass burning at Laguna Chaplin and across the Bolivian lowlands. During the late Holocene, increased fire activity across ecosystems ranging from fire-adapted to fire-intolerant forests is attributed to the apex of pre-Columbian activity. These data suggest human-caused ignitions during the late Holocene are the driving factor of regional scale fire activity in the Bolivian lowlands. After ca. 650 cal yr BP, there is an increase in biomass burning and fire frequency synchronous with the expansion of Moraceae/Urticaceae pollen (>50%) at Laguna Chaplin. This occurs during the time-transgressive southward expansion of the rainforest boundary, during the apex of pre-Columbian activity in the region. The increase in biomass burning at Laguna Chaplin is reflected at other sites in the region with known human occupation histories. The presence of Zea mays ca. 970 to 170 cal yr BP indicates maize cultivation is practiced in the immediate vicinity surrounding Laguna Chaplin. The simultaneous increase in fire activity with the expansion of the less flammable humid rainforest vegetation suggests human fire management practices. These data are interpreted as the use of frequent, low severity, human-caused fires to clear the croplands from encroaching rainforest vegetation. Despite evidence of pre-Columbian fire management during the late Holocene, vegetation and fire data indicate the extent of human-landscape modification and fire management at Laguna Chaplin, is not enough to inhibit the climate-driven regional forest expansion of the savanna-rainforest ecotonal boundary to its most southern extent in the last 50,000 years. This study demonstrates the utility of applying a multi-proxy, high-resolution paleoecological method to disentangle climate and pre-Columbian disturbance in the Bolivian Amazon.
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McMichael et al. state that we overlooked the effects of post-Columbian human activities in shaping current floristic patterns in Amazonian forests. We formally show that post-Columbian human influences on Amazonian forests are indeed important, but they have played a smaller role when compared to the persistent effects of pre-Columbian human activities on current forest composition.
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Levis et al. (Research Articles, 3 March 2017, p. 925) concluded that pre-Columbian tree domestication has shaped present-day Amazonian forest composition. The study, however, downplays five centuries of human influence following European arrival to the Americas. We show that the effects of post-Columbian activities in Amazonia are likely to have played a larger role than pre-Columbian ones in shaping the observed floristic patterns.
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Amazonian dark earths (ADE) are anthropogenic soils mostly created between 500 and 2500 years ago by pre-Columbian populations. ADE are currently used by local people for different agricultural and agroforestry systems. Because of their high fertility they may play an important role in the conservation of non-native agrobiodiversity. This study aimed to investigate the variation in richness and abundance of exotic and native species in homegardens along the ADE-background soil continuum. We conducted floristic inventories in 70 homegardens located in 7 riverside communities along the lower and middle Madeira River, Central Amazonia. Each species sampled was classified according to its origin: native Amazonian, American (from outside Amazonia) and non-American, and each individual was classified according to its form of establishment: cultivated or spontaneous. The floristic diversity was significantly related to soil fertility, texture and homegarden size. We found a positive relationship between soil fertility and richness of species and landraces. Homegardens on more fertile soils tended to have a higher richness and abundance of cultivated non-American species, as well as a higher richness and abundance of spontaneously established American species. Homegardens at the fertile end of the fertility gradient provided conditions for the establishment and growth of many species, especially exotic species, that are generally more nutrient-demanding than Amazonian species. Our results show that homegarden agroecosystems on ADE favour experimentation with the introduction of a wide range of species from various regions of the globe.
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Significant human impacts on tropical forests have been considered the preserve of recent societies, linked to large-scale deforestation, extensive and intensive agriculture, resource mining, livestock grazing and urban settlement. Cumulative archaeological evidence now demonstrates, however, that Homo sapiens has actively manipulated tropical forest ecologies for at least 45,000 years. It is clear that these millennia of impacts need to be taken into account when studying and conserving tropical forest ecosystems today. Nevertheless, archaeology has so far provided only limited practical insight into contemporary human–tropical forest interactions. Here, we review significant archaeological evidence for the impacts of past hunter-gatherers, agriculturalists and urban settlements on global tropical forests. We compare the challenges faced, as well as the solutions adopted, by these groups with those confronting present-day societies, which also rely on tropical forests for a variety of ecosystem services. We emphasize archaeology's importance not only in promoting natural and cultural heritage in tropical forests, but also in taking an active role to inform modern conservation and policy-making.
The nature of subsistence strategies employed by the past inhabitants of Amazonia has been a widely debated topic, however little evidence has been found so far in order to support some of the proposed hypotheses. This article contributes to this debate by presenting new δ¹³C and δ¹⁵N data from the human populations that occupied the Maracá region of the mouth of the Amazon river, around 500 BP (years before present). It directly compares these newly generated results to previously published human isotope data from neighbouring Marajó Island (Marajoara phase, 1600 to 700 BP), as well as other areas in the lowland Neotropics, in an attempt to build a bigger picture of the dietary habits of the Lower Amazon pre-colonial populations. The overall results suggest that the populations that occupied the mouth of the Amazon after 2000 BP had diets based on the exploitation of fish and a wide range of C3 plant resources, as well as possibly having a minor C4 or CAM component. The data presented are also consistent with an emerging consensus that there was no single adaptive pattern for ancient Amazonian populations and proposes that diversified economic strategies based on wild and cultivated plants combined with the exploitation of faunal resources could have developed over time and sustained long-term successful patterns of human occupations.