ArticlePDF Available

Abstract and Figures

Locally extensive pre-Columbian human occupation and modification occurred in the forests of the central and eastern Amazon Basin, but whether comparable impacts extend westward and into the vast terra firme (interfluvial) zones, remains unclear. We analyzed soils from 55 sites across central and western Amazonia to assess the history of human occupation. Sparse occurrences of charcoal and the lack of phytoliths from agricultural and disturbance species in the soils during pre-Columbian times indicated that human impacts on interfluvial forests were small, infrequent, and highly localized. No human artifacts or modified soils were found at any site surveyed. Riverine bluff areas also appeared less heavily occupied and disturbed than similar settings elsewhere. Our data indicate that human impacts on Amazonian forests were heterogeneous across this vast landscape.
Content may be subject to copyright.
DOI: 10.1126/science.1219982
, 1429 (2012);336 Science
et al.C. H. McMichael
Sparse Pre-Columbian Human Habitation in Western Amazonia
This copy is for your personal, non-commercial use only.
clicking here.colleagues, clients, or customers by
, you can order high-quality copies for yourIf you wish to distribute this article to others
here.following the guidelines
can be obtained byPermission to republish or repurpose articles or portions of articles
): June 15, 2012 www.sciencemag.org (this information is current as of
The following resources related to this article are available online at
http://www.sciencemag.org/content/336/6087/1429.full.html
version of this article at:
including high-resolution figures, can be found in the onlineUpdated information and services,
http://www.sciencemag.org/content/suppl/2012/06/13/336.6087.1429.DC1.html
can be found at: Supporting Online Material
http://www.sciencemag.org/content/336/6087/1429.full.html#related
found at:
can berelated to this article A list of selected additional articles on the Science Web sites
http://www.sciencemag.org/content/336/6087/1429.full.html#ref-list-1
, 11 of which can be accessed free:cites 38 articlesThis article
http://www.sciencemag.org/cgi/collection/anthro
Anthropology
subject collections:This article appears in the following
registered trademark of AAAS.
is aScience2012 by the American Association for the Advancement of Science; all rights reserved. The title
CopyrightAmerican Association for the Advancement of Science, 1200 New York Avenue NW, Washington, DC 20005.
(print ISSN 0036-8075; online ISSN 1095-9203) is published weekly, except the last week in December, by theScience
on June 15, 2012www.sciencemag.orgDownloaded from
7. W. K. Hartmann, G. Ryder, L. Dones, D. Grinspoon, in
Origin of the Earth and Moon, R. Canup, K. Righter, Eds.
(Univ. of Arizona Press, Tucson, AZ, 2000), pp. 805826.
8. R. G. Strom, R. Malhotra, T. Ito, F. Yoshida, D. A. Kring,
Science 309, 1847 (2005).
9. U. G. Jørgensen et al., Icarus 204, 368 (2009 ).
10. H. F. Levison, L. Dones, C. R. Chapman, S. A. Stern,
Icarus 151, 286 (2001).
11. R. S. Gomes, H. F. Levison, K. Tsiganis, A. Morbidelli,
Nature 435, 466 (2005).
12. V. Zappala, A. Cellino, B. J. Gladman, S. Manley,
F. Migliorini, Icarus 134, 176 (1998).
13. K. H. Joy, D. A. Kring, D. D. Bogard, D. S. McKay,
M. E. Zolensky, Geochim. Cosmochim. Acta 75, 7208
(2011).
14. J. J. Papike, L. A. Taylor, S. B. Simon, in Lunar
SourcebookA Users Guide to the Moon, G. Heiken,
D. Vaniman, B. French, Eds. (Cambridge Univ. Press.,
Cambridge, 1991), pp. 121181.
15. J. W. Morgan, R. Ganapathy, H. Higuchi, U. Krahenbuhl,
E. Anders, Proc. Lunar Sci. Conf. 5, 1703 (1974).
16. I. S. Puchtel, R. J. Walker, O. B. James, D. A. Kring,
Geochim. Cosmochim. Acta 72, 3022 (20 08).
17. P. H. Warren, J. T. Wasson, Lunar Planet. Sci. Conf. 9,
185 (1978).
18. M. D. Norman, V. C. Bennett, G. Ryder, Earth Planet.
Sci. Lett. 202, 217 (2002).
19. J. G. Liu, M. G. Galenas, I. S. Puchtel, R. J. Walker,
Lunar Planet. Sci. XLIII, abstr. 2366 (2012).
20. D. M. Barringer, Proc. Acad. Nat. Sci. Phila. 57, 861
(1905).
21. F. T. Kyte, Nature 396, 237 (1998).
22. J. A. Wood, U. B. Marvin, B. N. Powell, J. S. Dickey Jr.,
Smithsonian Astrophysical Observatory Special Report
307 (Smithsonian Astrophysical Observatory,
Cambridge, MA, 1970).
23. W. Quaide , T. Bun ch, Proc. Lunar Sci. Conf. 1, 711
(1970).
24. B. L. Jolliff, R. L. Korotev, L. A. Haskin, Lunar Planet.
Sci. Conf. 24, 729 (1993).
25. A. E. Rubin, Meteorit. Planet. Sci. 32, 135 (1997).
26. M. E. Zolensky, Meteorit. Planet. Sci. 32 , 15 (1997).
27. J. M. D. Day, C. Floss, L. A. Taylor, M. Anand ,
A. D. Patchen, Geochim. Cosmochim. Acta 70, 5957
(2006).
28. D. S. McKay et al., Proc. Lunar Planet. Sci. Conf. 16,
D277 (1986).
29. D. Liu et al., Earth Planet. Sci. Lett. 319-320, 277
(2012).
30. C. K. Shearer, J. J. Papike, Geochim. Cosmochim. Acta
69, 3445 (2005).
31. S. M. Elardo, D. S. Draper, C. K. Shearer Jr.,
Geochim. Cosmochim. Acta 75, 3024 (2011).
32. S. J. Wentworth, D. S. McKay, Proc. Lunar Planet.
Sci. Conf. 18, 67 (1988).
33. C. K. Shearer, J. J. Papike, K. C. Galbreath,
S. J. Wentworth, N. Shimizu, Geochim. Cosmochim. Acta
54, 1851 (1990).
34. PetDB database, www.petdb.org/.
35. T. Nakamura et al., Science 321, 1664 (2008).
36. W. Klöck, K. Thomas, D. McKay, H. Palme, Nature 339,
126 (1989).
37. D. A. Kring, thesis, Harvard University, Cambridge,
MA (1988).
38. N. A. Artemieva, V. V. Shuvalov, Sol. Syst. Res. 42, 329
(2008).
39. L. Ong, E. I. Asphaug, D. Korycansky, R. F. Coker,
Icarus 207, 578 (2010).
40. K. Makide et al., Geochim. Cosmochim. Acta 73, 5018 (2009).
41. D. W. Mittlefehldt, R. N. Clayton, M. J. Drake, K. Righter,
Rev. Mineral. Geochem. 68, 399 (2008).
42. K. D. McKeegan et al., Science 332, 1528 (2011).
Acknowledgments: The data reported in this paper are
tabulated in the supplementary materials. This research was
funded by NASA Lunar Science Institute contract NNA09DB33A
(D.A.K.), NASA Cosmochemistry grant NNX11AG78G
(G.R.H.), and NASA Cosmochemistry grant NNX08AH77G
(K.N.). This is Lunar and Planetary Institute contribution
number 1665. We thank the three reviewers for helpful
comments and D. Mittlefehldt, J. Berlin, R. Jones,
and H. McSween for sharing meteorite data sets.
Supplementary Materials
www.sciencemag.org/cgi/content/full/science.1219633/DC1
Materials and Methods
Supplementary Text
Figs. S1 to S21
Tables S1 to S6
References (43132)
25 January 2012; accepted 2 May 2012
Published online 17 May 2012;
10.1126/science.1219633
Sparse Pre-Columbian Human
Habitation in Western Amazonia
C. H. McMichael,
1
* D. R. Piperno,
2
M. B. Bush,
1
M. R. Silman,
3
A. R. Zimmerman,
4
M. F. Raczka,
1
L. C. Lobato
5
Locally extensive pre-Columbian human occupation and modification occurred in the forests of
the central and eastern Amazon Basin, but whether comparable impacts extend westward and into
the vast terra firme (interfluvial) zones, remains unclear. We analyzed soils from 55 sites across
central and western Amazonia to assess the history of human occupation. Sparse occurrences of
charcoal and the lack of phytoliths from agricultural and disturbance species in the soils during
pre-Columbian times indicated that human impacts on interfluvial forests were small, infrequent,
and highly localized. No human artifacts or modified soils were found at any site surveyed.
Riverine bluff areas also appeared less heavily occupied and disturbed than similar settings
elsewhere. Our data indicate that human impacts on Amazonian forests were heterogeneous
across this vast landscape.
T
he Amazon Basin, an area approximately
the size of the continental United States,
is an important reservoir of biodiversity.
A major recent question is the degree to which
humans settled and modified Amazonian land-
scapes before European contact. It was initial-
ly thought that prehistoric Amazonia supported
mainly small and highly mobile human popula-
tions, who exerted little impact on their environ-
ments (1, 2), but recent work has documented
dense and complex human settlements in eastern
Amazonia and on the river bluffs of the central
Amazon. The evidence includes the presence of
highly modified soils such as terra pretas (anthro-
pogenic black earth)(3) and large-scale land-
scape alterations (Fig. 1) (4, 510). The evidence
is impressive, but comes largely from riverine
environments with abundant natural resources,
especially river bluffs, or the driest parts of the
eastern Amazon (Fig. 1).
The extent of this impact on terra firme set-
tings has been uncertain. The terra firme forests
of the interfluvial zone occupy 95% of Amazonia
and have less-fertile soils and poorer-quality
resources (11). Available data from several re-
gions suggest that the prehistoric impacts on in-
terfluvial landscapes were heterogeneous and
highly localized (12, 13). Here we reconstruct
histories of fire, vegetation, and soil modification
from charcoal, phytolith, and geochemical data
recovered from 247 soil cores collected from 55
locations, including sites with known impacts,
across 3,000,000 km
2
in western Amazonia
(Fig. 1 and table S1) (14). We sampled soils
from sites where the probability of past distur-
bances was high, such as river bluffs with known
archaeological hist or i es an d ne ar b y ter ra pretas ,
including T efe, Barcelos, and Iquitos; from a
previously unstudied river bluff at Los Ami-
gos; and from terra firme sites, including Acre,
Iquitos, Tefe, and a transect from Porto Velho
to Manaus (PVM).
Natural fires in Amazonia are rare today
(1517), but fire was a mainstay of prehistoric
land use in the tropics (11, 18, 19). Consequent-
ly, charcoal recovered from soils can provide
evidence of past human disturbances, and phy-
toliths, which document mature and disturbed
vegetation, reflect the intensity of those occupa-
tions. In our samples, charcoal was most com-
mon in soils from riverine bluffs, especially in the
central basin (Fig. 2, C to F). At Barcelos and
Tefe, charcoal was present in many intervals in
most cores, especially from 0 to 40 cm (Fig. 2, D
and F). Charcoal dates ranged from ca. 500 to
2700 calendar years before the present (cal yr
B.P.) at Tefe and from ca. 1200 to 130 0 cal yr B.P.
at Barcelos (table S2). The vegetation at Tefe
appears to have been more heavily affected than
that at Barcelos, which is in agreement with the
1
Department of Biological Sciences, Florida Institute of Tech-
nology, Melbourne, FL 32901, USA.
2
Program in Human Ecology
and Archaeobiology, Department of Anthropology, Smithsonian
National Museum of Natural History, Washington, DC 20560,
USA, and Smithsonian Tropical Research Institute, Balboa,
Panama.
3
Department of Biology, Wake Forest University,
Winston-Salem, NC 27106, USA, and Center for Energy, En-
vironment and Sustainability, Winston-Salem, NC 27106, USA.
4
Department of Geologi cal Sciences, University of Florida,
Williamson Hall, Gainesville, FL 32611, USA.
5
cleo de Ciência e
Tecnologia, Laboratório de Geografia Humana e Planejamento
Ambiental, Universidade Federal de Rondônia, Porto Velho,
Rondônia, Brazil.
*To whom correspondence should be addressed. E-mail:
cmcmicha@my.fit.edu
www.sciencemag.org SCIENCE VOL 336 15 JUNE 2012 1429
REPORTS
on June 15, 2012www.sciencemag.orgDownloaded from
longer span of documented occupation. In river-
ine settings, T efe soil phytoliths contained elevated
amounts of early successional herbaceous taxa
(ESH, such as grasses, Heliconia, and sedges)
and som e g r a ss phytoliths that were burned. These
patterns probably reflect forest clearing and other
human disturbances (see phytolith analyses in the
supplementary materials and fig. S1). Howev-
er, neither site yielded crop phytoliths. Arboreal-
dominated phytolith assemblages and relatively
sparse charcoal from riverine Iquitos sites indicate
that the forest remained relatively undisturbed
there, and nutrients and black carbon concentra-
tions in soils from these sites were low. At Los
Amigos, the charcoal dates ranged from 1000 to
4000 cal yr B.P. (table S2), but the soils were not
enriched in nutrients and arboreal taxa domi-
nated phytolith assemblages, which is consistent
with a light and shifting human impact (table S4,
Fig. 2E, and fig. S1).
We recovered little charcoal from soils at
Acre or interfluvial Iquitos sites, indicating a lack
of recurrent or extensive fires over the past sev-
eral thousand years (Fig. 2, A and C, and table S2).
Similar results were obtained from the phytolith
records, which were dominated by forest taxa;
ESH phytoliths were absent or rare (0 to 1%).
No evidence for crops or burned phytoliths was
found (fig. S1). Charcoal was more common in
soils of the PVM transect than in the western in-
terfluvial Iquitos or Acre sites (Fig. 2, A to C).
However, phytolith records showed no signs of
a significant human presence at most sites. ESH
phytoliths were absent or scarce (0 to 6%), and
burned tree phytoliths were nearly absent (Fig.
2B and fig. S1); forest taxa dominated in all
samples. Site 121 contained evidence of maize
cultivation and elevated frequencies of grass and
Heliconia phyoliths, many of which were burned.
No other crops, including squash (Cucurbita spp.),
manioc (Manihot esculenta), arrowroot (Maranta
arundinacea), and leren (Calathea allouia), were
found. Because manioc produces fewer phy-
toliths than many other crops, we cannot state
with the same confidence that it was not grown
nearby.
We found no prehistoric ceramics, stone
tools, or terra pretas in any of the 247 soil cores,
and none of 184 samples analyzed for phytoliths
contained evidence of intensive or persistent forest
clearing. In many soil levels, no ESH phytoliths
were observed in scans of >500 to 1000 addi-
tional phytoliths, underscoring the lack of dis-
turbance that took place in these interfluvial
forests. T ogether, the data suggest that human
population densities in the sampled regions were
low and highly localized, and were not consist-
ent with major population centers with associated
areas of widespread, extensive agriculture (20).
Our data support the idea that humans had much
less impact on interfluvial forests t han on riverine
environments (21) or in the drier eastern forests
(22). However, even regions with known human
sites and terra pretas (such as Barcelos and T efe)
were not subjected to continuous or large-scale
forest clearing or intensive agriculture (Fig. 2),
and show a lesser disturbance signature than found
in modern slash-and-burn systems (see phytolith
analyses in the supplementary materials). Forest
clearings were probably small and short-lived,
and the interior forests were apparently not per-
manently or intensively occupied by humans in
prehistory . We found little indication that repeated
fire, vegetational disturbance, and/or agriculture
extended more than 5 km into the terra firme
forests of the T efe, PVM, Acre, and Iquitos re-
gions (Fig. 2).
Our data imply that the disturbance signature
was stronger in both riverine and interfluvial
forestsofthecentralbasinthaninthewestern
basin (Fig. 2). Even in the PVM transect, how-
ever , evidence for disturbances was patchy and
localized, despite being l ocated 20 to 50 km from
the Madeira River and within 100 to 200 km of
dense concentrations of terra pretas (23) (Fig. 1).
The frequency and distribution of terra pretas doc-
umented along the Madeira River (24)mayhave
continued southward, parallel to our interfluvial
transect. The resulting contrasting pattern of highly
concentrated terra preta soils along the river, with
localized and patchy disturbance 20 to 50 km into
the uplands, illustrates how even in the central
Amazon, intensive landscape modific ation s ap-
pear to be confined to near-riverine locations.
We interpret the charcoal presence along with
low frequencies of burned tree phytoliths, and
the dominance of forest over grass phytoliths, to
mean that fires were mainly confined to the forest
floor . The apparently infrequent and low-intensity
fires do not appear to have penetrated canopies
and altered forest structure substantially at most
sites. Therefore, soil charcoal alone should not
be taken to mean that fires were of sufficient in-
tensity and duration to cause canopy disruption
and major forest alteration [see also (12)].
It is likely that in some forests, edible or other
useful fruit trees were planted or managed, re-
sulting in an enrichment of those species (25).
Palms such as peach palm (Bactris gasipaes)and
Astr ocaryum are economic mainstays in the Am-
azon and are prolific phytolith producers. We
found no evidence for these species in most sam-
ples from every site studied (fig. S1 and palm
distributions in the supplementary materials).
There was no association between palm phytolith
fre qu en c ie s and other evidence of vegetation dis -
turbance, and palm frequencies were never so
high that they implied that a local grove was
present. These data suggest that humans were
not cultivating or selectively managing palms at
most of our study sites. There was also no indi-
cation that many noneconomic species were sel-
ectively removed (26), because little change in
forest composition was seen from the bottom to
the top of the soil cores, including when early suc-
cessional herbaceous taxa and/or charcoal were
present.
Our data imply that the terra firme forests we
studied in the western Amazon Basin were
Fig. 1. Sampled locations within western Amazonia (white squares) in relation to major pre-Columbian
archaeological sites (1, Marajó Island; 2, Santarém; 3, Upper Xingu; 4, Central Amazon Project; 5,
Bolivian Beni), known terra preta locations (brown circles) (3, 32, 33), and soil charcoal survey locations
(black circles) (12, 22). Charcoal and phytolith data are presented from regions outlined in black (B,
Barcelos; T, Tefe; PVM, Porto Velho-Manaus transect; I, Iquitos; Ac, Acre; LA, Los Amigos). The locations of
Rio Madeira and associated terra pretas are shown. Here we define Amazonia as the region drained by the
Amazon River and its tributaries.
15 JUNE 2012 VOL 336 SCIENCE www.sciencemag.org
1430
REPORTS
on June 15, 2012www.sciencemag.orgDownloaded from
predominantly occupied by relatively small and
shifting human populations during the pre-
Columbian era. This has many implications for
hypotheses about human effects on Amazonian
forests. First, humans may have augmented the
alpha-diversity of some Amazonian landscapes,
but the hyperdiverse floras and faunas are mo re a
product of long-term evolutionary and ecological
processes (27) than anthropic landscape altera-
tion (4, 26, 2830 ). Second, to the extent that
prehistoric deforestation occurred, it was appar-
ently primarily in the eastern Amazon, and this
may have limited the proposed impact of post-
Columbian population collapse and reforestation
on atmospheric CO
2
and CH
4
levels (18, 31).
Third, we canno t assume that Amazonian forests
were resilient in the face of heavy pre-Columbian
disturbance, because vast areas were probably
never heavily disturbed. Prehistoric peoples set-
tled most densely in habitats where resources
were abundant and easily captured, fertile soils
were available, and transportation routes were
nearby, making ecological factors important in
pre-Columbian settlement patterns.
References and Notes
1. B. J. Meggers, Amazonia: Man and Culture in a
Counterfeit Paradise; Worlds of Man: Studies in Cultural
Ecology (Aldine-Atherton, Chicago, 1971).
2. B. J. Meggers, Rev. Archaeol. 25, 31 (2004).
3. J. Lehmann, D. C. Kern, B. Glaser, W. I. Woods,
Amazonian Dark Earths: Origin, Properties, Management
(Kluwer Academic, Dordrecht, Netherlands, 2003).
4. C. L. Erickson, in Time and Complexity in Historical
Ecology, W. Balee, C. L. Erickson, Eds. (Columbia Univ.
Press, New York, 2006), pp. 235278.
5. M. J. Heckenberger, J. C. Russell, J. R. Toney, M. J. Schmidt,
Philos. Trans. R. Soc. London Ser. B 362, 197 (2007).
6. B. J. Meggers, C. Evans, Archeological Investigations at
the Mouth of the Amazon (Bureau of American Ethnology,
Washington, DC, 1957).
7. E. Neves, J. Petersen, in Time and Complexity in
Historical Ecology: Studies in the Neotropical Lowlands,
W. Balee, C. L. Erickson, Eds. (Columbia Univ. Press,
New York, 2006), pp. 279310.
8. A. C. Roosevelt, Moundbuilders of the Amazon:
Geophysical Archaeology on Marajó Island, Brazil
(Academic Press, San Diego, CA, 1991).
9. A. C. Roosevelt, R. A. Housley, M. I. DA Silveira,
S. Maranca, R. Johnson, Science 254, 1621 (1991).
10. M. J. Heckenberger et al., Science 301, 1710 (2003).
11. D. R. Piperno, D. M. Pearsall, The Origins of Agriculture in
the Lowland Neotropics (Academic Press, San Diego,
CA, 1998).
12. C. McMichael et al., Holocene 22, 131 (2012).
13. D. R. Piperno, P. Becker, Quat. Res. 45, 202 (1996).
14. Site descriptions and materials and methods are
available as supplementary materials on Science Online
15. L. Aragão et al., Geophys. Res. Lett. 34, L07701 (2007).
16. Y. Malhi et al., Proc. Natl. Acad. Sci. U.S.A. 106, 20610
(2009).
17. D. Nepstad et al., Glob. Change Biol. 10, 704 (2004).
18. R. A. Dull et al., Ann. Assoc. Am. Geogr. 100, 755 (2010).
19. D. R. Piperno, in Tropical Rainforest Response to Climatic
Change, M. B. Bush, J. R. Flenley, Eds. (Springer,
Chichester, UK, 2007), pp. 185212.
20. R. Nevle, D. Bird, W. Ruddiman, R. Dull, Holocene 21,
853 (2011).
21. W. M. Denevan, Ann. Assoc. Am. Geogr. 86, 654 (1996).
22. M. B. Bush, M. R. Silman, C. McMichael, S. Saatchi,
Philos. Trans. R. Soc. London Ser. B 363 , 1795 (2008).
23. M. Heckenberger, E. G. Neves, Annu. Rev. Anthropol. 38,
251 (2009).
24. J. Fraser, A. Junqueira, N. Kawa, C. Moraes, C. Clement,
Hum. Ecol. 39, 395 (2011).
25. C. R. Clement, in Time and Complexity in Historical
Ecology: Studies in the Neotropical Lowlands, W. Balee,
C. L. Erickson, Eds. (Columbia Univ. Press, New York,
2006), pp. 165186.
26. C. L. Erickson, in The Handbook of South American
Archaeology, H. Silverman, W. H. Isbell, Eds. (Springer,
New York, 2008), pp. 157183.
27. E. G. Leigh Jr., et al., Biotropica 36, 447 (2004).
28. W. Balee, C. L. Erickson, Time, Complexity, and Historical
Ecology (Columbia Univ. Press, New York, 2006).
29. C. L. Erickson, Diversity 2, 618 (2010).
30. C. C. Mann, 1491: New Revelations of the Americas
Before Columbus (Knopf, New York, 2005).
31. R. J. Nevle, D. K. Bird, W. F. Ruddiman, R. A. Dull,
Holocene 21, 853 (2011).
32. B. Glaser, W. I. Woods, Amazonian Dark Earths:
Explorations in Space and Time (Springer-Verlag, Berlin,
2004).
33. S. P. Aldrich, A. M. G. A. WinklerPrins, J. Latin Am. Geogr.
9, 33 (2010).
Acknowledgments: Field work and
14
C dating of charcoal
fragments were funded by the NSF Ecology Program
(awards DEB 0742301 and DEB 0743666). Other funding
was provided by the Florida Institute of Technology; the
Smithsonian National Museum of Natural History, including
a Restricted Endowment and Small Grant Award; and the
Smithsonian Tropical Research Institute. All data will be
deposited in the Neotoma Database (www.neotomadb.org/).
We thank B. McMichael, A. Correa-Metrio, J. Hernandez,
T. Harrison, and B. Rado for field assistance.
Supplementary Materials
www.sciencemag.org/cgi/content/full/336/6087/1429/DC1
Materials and Methods
Supplementary Text
Fig. S1
Tables S1 to S4
References (3465)
2 February 2012; accepted 16 April 2012
10.1126/science.1219982
Fig. 2. Regionalmaps,soilcharcoaldistributions,andphytolithpercentagesforsoilcoresfromriverine
(red squares and text) and interfluvial (black squares and text) sites in each region: Acre (A), PVM (B),
Iquitos (C), Tefe (D),LosAmigos(E), and Barcelos (F). Areas of lower (darker) and higher (lighter)
elevations illustrate drainage and rivers (from 90-mresolution data from the Shuttle Radar Topography
Mission) on each regional map. Colored boxes indicatecharcoalresultsforeachcorewithineachsite
(see legend). Sites are listed in a north-to-south orientation. Soil cores with accompanying phytolith
data are denoted with P. Phytolith percentages (column P) are listed to the right of the charcoal results.
Geographic coordinates of all sites are provided in table S3.
www.sciencemag.org SCIENCE VOL 336 15 JUNE 2012
1431
REPORTS
on June 15, 2012www.sciencemag.orgDownloaded from
... At Site 7, these phytoliths also increase significantly from 3 to 12% from 60 to 3 cm b.s., and to 21% in the surface sample. Judging from directly dated phytoliths from other terrestrial soil profiles (e.g., McMichael et al., 2012;Piperno et al., 2015Piperno et al., , 2021, the increase to 12% at 3-20 cm b.s. likely occurred during the past 2,000 to 3,000 years. ...
Article
Full-text available
Efforts to naturally remove atmospheric CO2 demand that largely intact forests be maintained. Our inter-cultural research initiative tested the hypothesis that Indigenous custody of the land is compatible with the maintenance of intact forests. Here we combined traditional knowledge, phytolith analysis, remote sensing, and tree inventories to study old-growth forests in Panama's Darién. Phytoliths served to elucidate historical vegetation, remote sensing revealed the current and past Indigenous footprints while tree stature and identity characterised the forest. Until now there has been very little to no human impact within these forests and current Indigenous footprint is both small and stable. Large trees accounted for 13% of trees in the plots that we established. For over half of the species, the measured tree height was taller than previously published maximum heights, leading us to conclude that these forests are a truly exceptional ecological refugium. Noting that the local communities are not rewarded for their custody of these exceptional forests we call to revisit the Good Practice Guidance for Land Use Land Use Change and Forestry to include intact forest land. In the context of sub-optimal carbon finance options, we also propose matching as a methodology that could prove additionality of forest conservation initiatives in climate mitigation portfolios.
... In aseasonal western Amazonia, settlements were often temporally and spatially intermittent compared with more distinct dry season settings. Localized disturbance was strongly influenced by distance from rivers, lakes, seasonal flood-plains, and savannas Bush et al., 2007;Bush and Colinvaux, 1988;Kelly et al., 2018aKelly et al., , 2018bMcMichael et al., 2012bMcMichael et al., , 2015McMichael et al., , 2012aRoucoux et al., 2013). ...
Article
Tropical peatlands are a globally important carbon store. They host significant biodiversity and provide a range of other important ecosystem services, including food and medicines for local communities. Tropical peatlands are increasingly modified by humans in the rapid and transformative way typical of the “Anthropocene,” with the most significant human—driven changes to date occurring in Southeast Asia. This review synthesizes the dominant changes observed in human interactions with tropical peatlands in the last 200 years, focusing on the tropical lowland peatlands of Southeast Asia. We identify the beginning of transformative anthropogenic processes in these carbon-rich ecosystems, chart the intensification of these processes in the 20th and early 21st centuries, and assess their impacts on key ecosystem services in the present. Where data exist, we compare the tropical peatlands of Central Africa and Amazonia, which have experienced very different scales of disturbance in the recent past. We explore their global importance and how environmental pressures may affect them in the future. Finally, looking to the future, we identify ongoing efforts in peatland conservation, management, restoration, and socio-economic development, as well as areas of fruitful research toward sustainability of tropical peatlands.
... Fires are not a natural phenomenon in the Amazon region (Bush et al., 2004;McMichael et al., 2012); they are used for food security, hunting and religious rituals by Indigenous Peoples and traditional communities (Hecht, 2006;Carmenta et al., 2019;da Cunha, 2020), and also as a widespread technique for land clearing for small-and large-scale farms for agriculture (Morello et al., 2019). The dramatically increased forest burning observed in the Amazon recently are the result of illegal land grabbing, the small-a and large-scale cattle ranching sector and agribusiness practices coupled with loosening of land tenure policies and decision makers' neglect of deforestation and burning monitoring data (Nobre et al., 2016;Lovejoy and Nobre, 2018;Leal Filho et al., 2020a (Alencar et al., 2020). ...
... Our results put to rest arguments that western Amazonia was sparsely populated in pre-Hispanic times 28 . The architectural layout of large settlement sites of the Casarabe culture indicates that the inhabitants of this region created a new social and public landscape through monumentality. ...
Article
Full-text available
Archaeological remains of agrarian-based, low-density urbananism1–3 have been reported to exist beneath the tropical forests of Southeast Asia, Sri Lanka and Central America4–6. However, beyond some large interconnected settlements in southern Amazonia7–9, there has been no such evidence for pre-Hispanic Amazonia. Here we present lidar data of sites belonging to the Casarabe culture (around ad 500 to ad 1400)10–13 in the Llanos de Mojos savannah–forest mosaic, southwest Amazonia, revealing the presence of two remarkably large sites (147 ha and 315 ha) in a dense four-tiered settlement system. The Casarabe culture area, as far as known today, spans approximately 4,500 km2, with one of the large settlement sites controlling an area of approximately 500 km2. The civic-ceremonial architecture of these large settlement sites includes stepped platforms, on top of which lie U-shaped structures, rectangular platform mounds and conical pyramids (which are up to 22 m tall). The large settlement sites are surrounded by ranked concentric polygonal banks and represent central nodes that are connected to lower-ranked sites by straight, raised causeways that stretch over several kilometres. Massive water-management infrastructure, composed of canals and reservoirs, complete the settlement system in an anthropogenically modified landscape. Our results indicate that the Casarabe-culture settlement pattern represents a type of tropical low-density urbanism that has not previously been described in Amazonia. Two remarkably large sites in southwest Amazonia, belonging to the Casarabe culture, include complex civic-ceremonial architecture and large water-management infrastructure, representing a type of tropical low-density urbanism that has not previously been described in Amazonia.
... Reported 14 C dates of fire vary widely among sites and regions of Amazonia, with few assessments of charcoal in terra firme soils (Piperno and Becker, 1996;Hammond and ter Steege, 1998;McMichael et al., 2012). Understanding this variation and its impacts upon the record that is reflected in Amazonian soil stratigraphies is important for developing sampling and analysis strategies. ...
Article
Full-text available
Fire has a historical role in tropical forests related to past climate and ancient land use spanning the Holocene; however, it is unclear from charcoal records how fire varied at different spatiotemporal scales and what sampling strategies are required to determine fire history and their effects. We evaluated fire variation in structurally intact, terra-firme Amazon forests, by intensive soil charcoal sampling from three replicate soil pits in sites in Guyana and northern and southern Peru. We used radiocarbon ( ¹⁴ C) measurement to assess (1) locally, how the timing of fires represented in our sample varied across the surface of forest plots and with soil depth, (2) basin-wide, how the age of fires varies across climate and environmental gradients, and (3) how many samples are appropriate when applying the ¹⁴ C approach to assess the date of last fire. Considering all ¹⁴ C dates ( n = 33), the most recent fires occurred at a similar time at each of the three sites (median ages: 728–851 cal years BP), indicating that in terms of fire disturbance at least, these forests could be considered old-growth. The number of unique fire events ranged from 1 to 4 per pit and from 4 to 6 per site. Based upon our sampling strategy, the N-Peru site—with the highest annual precipitation—had the most fire events. Median fire return intervals varied from 455 to 2,950 cal years BP among sites. Based on available dates, at least three samples (1 from the top of each of 3 pits) are required for the sampling to have a reasonable likelihood of capturing the most recent fire for forests with no history of a recent fire. The maximum fire return interval for two sites was shorter than the time since the last fire, suggesting that over the past ∼800 years these forests have undergone a longer fire-free period than the past 2,000–3,500 years. Our analysis from terra-firme forest soils helps to improve understanding of changes in fire regime, information necessary to evaluate post-fire legacies on modern vegetation and soil and to calibrate models to predict forest response to fire under climate change.
... Reported 14 C dates of fire vary widely among sites and regions of Amazonia, with few assessments of charcoal in terra firme soils (Piperno and Becker, 1996;Hammond and ter Steege, 1998;McMichael et al., 2012). Understanding this variation and its impacts upon the record that is reflected in Amazonian soil stratigraphies is important for developing sampling and analysis strategies. ...
Article
Fire has a historical role in tropical forests related to past climate and ancient land use spanning the Holocene; however, it is unclear from charcoal records how fire varied at different spatiotemporal scales and what sampling strategies are required to determine fire history and their effects. We evaluated fire variation in structurally intact, terra-firme Amazon forests, by intensive soil charcoal sampling from three replicate soil pits in sites in Guyana and northern and southern Peru. We used radiocarbon (14C) measurement to assess (1) locally, how the timing of fires represented in our sample varied across the surface of forest plots and with soil depth, (2) basin-wide, how the age of fires varies across climate and environmental gradients, and (3) how many samples are appropriate when applying the 14C approach to assess the date of last fire. Considering all 14C dates (n = 33), the most recent fires occurred at a similar time at each of the three sites (median ages: 728–851 cal years BP), indicating that in terms of fire disturbance at least, these forests could be considered old-growth. The number of unique fire events ranged from 1 to 4 per pit and from 4 to 6 per site. Based upon our sampling strategy, the N-Peru site—with the highest annual precipitation—had the most fire events. Median fire return intervals varied from 455 to 2,950 cal years BP among sites. Based on available dates, at least three samples (1 from the top of each of 3 pits) are required for the sampling to have a reasonable likelihood of capturing the most recent fire for forests with no history of a recent fire. The maximum fire return interval for two sites was shorter than the time since the last fire, suggesting that over the past ∼800 years these forests have undergone a longer fire-free period than the past 2,000–3,500 years. Our analysis from terra-firme forest soils helps to improve understanding of changes in fire regime, information necessary to evaluate post-fire legacies on modern vegetation and soil and to calibrate models to predict forest response to fire under climate change.
Article
The Napo River basin, which is situated within the Upper Amazon archaeological region, is one of the most speciose forests in Greater Amazonia. Standard thinking in scholarship and science holds that these forests are essentially pristine because any Indigenous impacts in the past would have been minimal, seedbanks would have been nearby, and natural forests would have reappeared after the humans left, died out, or dispersed. Inventory research in 2019 on three ridgetop forests in Waorani territory inside the Curaray basin (which drains to the right margin of the Napo River) and a comparable inventory on one control site forest along the Nushiño River (also in the Curaray basin) show human impacts from about the late nineteenth century to about 1960; they occurred during the period of wartime among Waorani themselves and between Wao people and outsiders. The human impacts resulted in the high basal-area presence of two long-lived species with important Waorani cultural uses: cacao ( Theobroma cacao L.) and ungurahua palm ( Oenocarpus bataua Mart.). These species have high frequency and dominance values and do not occur in the control site, which is comparable in terms of elevation above the flood zone of the rivers in the sample. These findings mean that alpha diversity in the right margin sector (or south) of the Napo River basin cannot a priori be explained by reference to traditionally, biologically accepted patterns of ecological succession but may require knowledge of historical patterns of Indigenous land use and secondary landscape transformation over time due to human (specifically Waorani) impacts of the past.
Article
A high-resolution paleoecological record provides a 2690 year-long fossil pollen and charcoal history from Lake Ayauch ⁱ , Ecuador, in lowland Amazonia. The record begins with a landscape that is already partially deforested and in which maize is being grown. Dated charcoal fragments from local soils coincide with fire events and peaks of land clearance seen in the lake sediment record. After c. AD 550 grass pollen becomes less abundant, as a broad array of forest types show small increases in abundance. Between c. AD 750 and 1280, Zea mays pollen was at its most abundant. Although maize cultivation continued until the AD 1700s, forest pollen abundance showed a significant increase at c. AD 1260. Another transition at c. AD 1420, which saw a transition from dominance by early successional taxa and an increase in mid-successional elements, suggests the onset of reduced human activity at the site. Fossil maize is found in a lower proportion of samples, disappearing altogether for a century in the late 1700s. Forest taxa increase in abundance and charcoal disappears from the record at c. AD 1790. These data suggest a complex social history prior to and following European arrival with phases of forest clearing and episodes of apparent regrowth at c. AD 500, 950, and 1260. Increased forest pollen after c. AD 1260 and a reduction in maize pollen abundance suggests some abandonment, with a second, relatively late, depopulation following European Conquest (c. AD 1790). Evidence is not found supporting reforestation associated with European arrival.
Article
Amazonian forest plots are used to quantify biodiversity and carbon sequestration, and provide the foundation for much of what is known about tropical ecology. Many plots are assumed to be undisturbed, but recent work suggests that past fire, forest openings, and cultivation created vegetation changes that have persisted for decades to centuries (ecological legacies). The Yasuní Forest Dynamics plot is one of the most biodiverse places on earth, yet its human history remains unknown. Here, we use charcoal and phytolith analysis to investigate the fire and vegetation history of the Yasuní forest plot, and compare results with nearby forest plots in Colombia (Amacayacu) and Peru (Medio Putumayo‐Algodón [MPA]) to explore the spatial variability of past disturbances and ecological legacies in northwestern Amazonia. Three 14C dated charcoal fragments provided evidence for a modern (1956 CE) and a past fire event ca. 750 years ago at Yasuní, compared with fire ages of 1000–1600 years ago documented at Amacayacu and MPA. Small‐scale disturbances and localized canopy openings also occurred in the Yasuní plot. Phytolith assemblages from Yasuní and Amacayacu showed more variability in past vegetation change than MPA. Low‐intensity, non‐continuous disturbances occurred at all three plots in the past, and our results highlight the variability of past human activities both in space and time in northwestern Amazonia. Our data also suggest that post‐Columbian human disturbances from the Rubber Boom (AD 1850–1920) and subsequent oil exploration have likely left stronger ecological legacies than those left by pre‐Columbian peoples in our studied regions. Forest plots in Amazonia are often assumed to be undisturbed, but recent work suggests that past people can affect modern vegetation composition in the form of ecological legacies. We investigated the past fire and vegetation history of the Yasuní Forest Dynamics plot and compared that to other forest plots in northwestern Amazonia. Our data suggest that post‐Columbian human disturbances from the Rubber Boom (AD 1850‐1920) and subsequent oil exploration have likely left stronger ecological legacies than those left by pre‐Columbian peoples in northwestern Amazonia.
Book
Amazonian Dark Earths are not only a testament to the vanished civilizations of the Amazon Basin, but may provide the answer to how the large, sophisticated societies were able to sustain intensive agriculture in an environment with mostly infertile soils. Locally known as Terra Preta de Indio or Indian black earth, these anomalous soils are even today fertile and highly productive. Though clearly associated with pre-European settlements questions remain whether the Dark Earths were intentionally produced or merely a by-product of habitation activities. This publication provides a comprehensive review of our current understanding of these fascinating soils: their origin, properties, and management through time. These new and multidisciplinary perspectives by leading experts on Amazonian Dark Earths may pave the way for the next revolution of soil management in the humid tropics.
Book
The regenerative qualities identified in prehistoric, anthropogenic Amazonian dark earths suggest that notoriously infertile tropical soils can be greatly improved. Soil enhancement practices by ancient Amerindians allowed them to cultivate the land intensively, without needing to continually clear new fields from forest. As increasing populations place ever greater pressure on tropical forests, this legacy of rich, 'living' soils warrants further study in the search for high-yield, land-intensive, yet sustainable forms of management. The international group of contributors to this volume provides a variety of stances centering on aspects of the origin, distribution, variability, persistence, and use of Amazonian dark earths.
Book
Biomass burning profoundly affects atmospheric chemistry, the carbon cycle, and climate and may have done so for millions of years. Bringing together renowned experts from paleoecology, fire ecology, atmospheric chemistry, and organic chemistry, the volume elucidates the role of fire during global changes of the past and future. Topics covered include: the characterization of combustion products that occur in sediments, including char, soot/fly ash, and polycyclic aromatic hydrocarbons; the calibration of these constituents against atmospheric measurements from wildland and prescribed fire emissions; spatial and temporal patterns in combustion emissions at scales of individual burns to the globe.
Chapter
Stratigraphic charcoal data are used to interpret combustion at a range of spatial and temporal scales. Interpretation is based on assumptions regarding how charred particles are transported to and deposited in sedimentary basins and how the variance structure of stratigraphie profiles is affected by transport. Here we examine evidence for “background” and “local” signals in stratigraphie data based on total abundances of particles and on distributions of particle sizes. Distributions of particle sizes in sediments and in the atmosphere show remarkable consistency, with a ~ 2% decrease in frequency for a 1% increase in particle diameter. Relatively large differences in source distance are required to produce differences in particle size distributions. Thus, stratigraphie samples with disproportionate representation of large particles are likely to represent a nearby source. Simple transport models suggest particles 100 to 101 μm have substantially longer atmospheric residence times than do particles > 102 μm. Several factors can produce a “dichotomy” (background vs local) in total abundances of charred particles. Transport during a single experimental burn shows abrupt decline in accumulation at a burn edge and relatively constant values out to 102 m. Saltation and redistribution of particles in surface runoff following fire are expected to focus accumulation within a catchment (local scale). The amount of transport that occurs by these modes is unstudied. The stratigraphie record appears to support a distinction between local, catchment sources vs. fires burning at greater distance. Charcoal profiles often show distinct peaks when fires burn within a lake catchment but are unaffected by fires that occur at greater distance. Broad subcontinental scale patterns in particle accumulation indicate shifts in regional importance of fire. The low frequency variance can be extracted from charcoal profiles and used to differentiate local from background changes in burning. Although the empirical data are still far too few to permit good characterization of particle transport, the evidence suggests utility in the concepts of background and local signals in profiles.