Cited by 179Amazonian Archaeology and EthnohistorySoil and Environmental StudiesArchaeology and ancient environmental studies

The DOI matches its Crossref record; 72 of the 73 references it cites were found in a registry or an index, and 1 are not checked yet; 8 of the 103 sources its claims cite were checked for support.

Predicting pre-Columbian anthropogenic soils in Amazonia

Open access
McMichael, C. H., Palace, M. W., Bush, M. B., Braswell, B., Hagen, S., Neves, E. G., Silman, M. R., Tamanaha, E. K., Czarnecki, C.·2014·Proceedings of the Royal Society B: Biological Sciences

Abstract

The extent and intensity of pre-Columbian impacts on lowland Amazonia have remained uncertain and controversial. Various indicators can be used to gauge the impact of pre-Columbian societies, but the formation of nutrient-enriched terra preta soils has been widely accepted as an indication of long-term settlement and site fidelity. Using known and newly discovered terra preta sites and maximum entropy algorithms (Maxent), we determined the influence of regional environmental conditions on the likelihood that terra pretas would have been formed at any given location in lowland Amazonia.Terra pretas were most frequently found in central and eastern Amazonia along the lower courses of the major Amazonian rivers. Terrain, hydrologic and soil characteristics were more important predictors of terra preta distributions than climatic conditions. Our modelling efforts indicated that terra pretas are likely to be found throughout ca 154 063 km 2 or 3.2% of the forest. We also predict that terra preta formation was limited in most of western Amazonia. Model results suggested that the distribution of terra preta was highly predictable based on environmental parameters. We provided targets for future archaeological surveys under the vast forest canopy and also highlighted how few of the long-term forest inventory sites in Amazonia are able to capture the effects of historical disturbance.

Verified 2026-11-10 · 1 reference not checked yet

Overview

AI snapshot

Written from the paper’s full text.

TL;DR

Using Maxent and 701 known terra preta presence sites, the authors model the environmental likelihood of pre-Columbian anthropogenic soil formation across lowland Amazonia. They estimate terra preta is likely across ca 154,063 km² (3.2% of forest), concentrated in central/eastern Amazonia and riverine settings, with limited western Amazonian occurrence.

Key findings

  • The model had high predictive capacity: mean AUC from 10-fold cross-validation was 0.957 ± 0.006; at a 0.25 probability threshold, 89% of known presence/absence sites were correctly classified, with a 6.5% false negative rate and 4.7% false positive rate.
  • Terrain, geological and hydrological characteristics were more important than climatic ones. Elevation was the most important predictor (permutation importance 61.4945%), constraining terra preta mainly to 0–100 m elevation; geological province was second (5.6174%), with highest likelihood in the Solimões Basin, Ucayali Basin and Brazilian Shield; probability was highest within 10 km of a river and near bluffs greater than 25 m.
  • Terra preta was predicted across ca 154,063 km², or 3.2% of the forest, less than previous estimates of as much as 10%. The model predicted terra preta was limited in most of western Amazonia and almost zero at major archaeological sites in Bolivia, including the Llanos de Moxos and the geoglyph-rich region.

Methods

  • Presence-only Maxent v. 3.3.3 modelling used 701 terra preta presence sites: 201 high-confidence sites from WinklerPrins & Aldrich, 8 from Paz et al., and 463 from E.G.N. and E.K.T. field surveys, across 4,876,193 km² of Amazonian forest.
  • The model included 22 environmental variables (9 climatic, 6 edaphic, 4 topographical, 2 hydrological, 1 geological) resampled to 90 m resolution.
  • Analyses included 10-fold cross-validation, AUC statistics, response curves, permutation importance and jackknife tests; predicted values were then extracted for 2,879 terra preta and terra preta-free sites, and a 0.25 threshold maximizing correct classification was used to estimate the area predicted as terra preta.

Limitations

  • The paper states that because most terra preta and terra preta-free sites lie in Brazil, the most confident predictions are for Brazil; elsewhere predictions are based on larger interpolations and are less certain, and increased sampling will refine estimates outside Brazil.
  • The paper states the model probably overestimates the areas where terra pretas will be found at any given time because it predicts the summed distribution across all ages; terra preta dates are not always contemporaneous, ranging from 3000 to 500 years ago, with most recorded dates from 1000 to 2000 years ago, and continuous occupation after original formation remains unknown.
  • The paper also notes that presence-only modelling was chosen partly because presence sampling was targeted and localized while terra preta-free datasets came from landscape-scale stratified sampling, and RADAM coordinates may be questionable because they predate modern GPS; RADAM and other regional surveys do not contain evidence of terra pretas, but it is not explicit whether they actually searched for them.

Model-written summary. Check it against the paper before relying on it.

Integrity signals

Registry

Crossref · 10.1098/rspb.2013.2475

Cites

72 of 73 references verified0 citation errors · 0 not checkable

Statistics

Nothing to recompute.

Verification

Claims the paper makes

8 of 103 cited sources checked · 1 supported · 0 flagged · accuracy not yet measured

Show all 50 claims

  • It may state two separate claims as one. 25
  • Probably not a substantial claim. 32
50 of 50
  • The paper relies on this without support.

    The potential for terra preta formation exists throughout Amazonia.

    “As the potential for terra preta formation exists throughout Amazonia, we hypothesized that regional environmental conditions and local sociocultural practices influenced how people lived and that, in turn, affected their likelihood of creating terra preta .”
  • The paper relies on this without support.

    Modern environmental conditions used as predictors are relevant to the likelihood of pre-Columbian terra preta formation across Amazonia.

    “we modelled the potential distribution of terra pretas based on presence locations and a suite of climatic, geological, terrain and hydrological conditions across Amazonia.”
  • The paper relies on this without support.

    A prediction of terra preta formation derived from empirical data and modelling is lacking.

    “Terra preta formation has been estimated to occur in as much as 10% of the forests [6,7], but a prediction derived from empirical data and modelling is lacking.”
  • The paper relies on this without support.

    None of the predicted highly impacted areas are as biodiverse as the forests of northwestern Amazonia, which contain the highest tree-species diversity per unit area.

    “None of the predicted highly impacted areas are as biodiverse as the forests of northwestern Amazonia, which contain the highest tree-species diversity per unit area.”
  • The paper relies on this without support.

    Most ecological data collection and field surveys, particularly in the Neotropics, have been conducted over recent timescales, i.e. the past 50 years.

    “Most ecological data collection and field surveys, particularly in the Neotropics, have been conducted over recent timescales, i.e. the past 50 years.”
  • The paper relies on this without support.

    The Llanos de Moxos region of Bolivia is located in seasonally inundated forests at the forest-savannah transition.

    “The Llanos de Moxos regions of Bolivia is located in seasonally inundated forests at the forest-savannah transition, and instead of terra preta formation, large societies sustained themselves by using techniques such as fish weirs and raised-field agriculture (e.g. [12]).”
6 of 6

Claims other papers make about this one

Each is checked against this paper’s own text: does it say what the citing paper says it does?

Self-check

Percentages, sums and reported differences re-computed from the paper’s own numbers.

  • Model-site counts total 672, not 701

    Minor

    The three stated groups of sites sum to 672, rather than the reported total of 701.

    Reported 701 · recomputed 672

  • Environmental-layer categories total 46, not 45

    Minor

    The listed categories contain 19 + 16 + 8 + 2 + 1 = 46 layers, one more than the stated total of 45.

    Reported 45 · recomputed 46

2 of 2

Citations

Cites

Flagged first, then by citations

Show all 70 references

Research works printed but not linked: 5

  1. Roosevelt AC, 1991, Moundbuilders of the Amazon: geophysical archaeology on Marajó Island
  2. Sombroek W, 2002, Proc. 17th World Congress of Soil Science
  3. Bow J, 2008, Terrestrial ecosystems of South America
  4. Freeman EA, 2008, Statist. Softw., 23, 1
  5. RStudio, 2012, RStudio: integrated development environment for R (version 0.96.331)

Cited by

Sorted by citations

Items 101–178 of 178

Metadata

Authors
McMichael, C. H., Palace, M. W., Bush, M. B., Braswell, B., Hagen, S., Neves, E. G., Silman, M. R., Tamanaha, E. K., & Czarnecki, C.
Affiliations
  • Earth Systems Research Center, University of New Hampshire, Durham, NH 03824, USA
  • Department of Biological Sciences, Florida Institute of Technology, Melbourne, FL 32901, USA
  • Applied Geosolutions, Durham, NH 03824, USA
  • Laboratório de Arqueologia dos Trópicos, Museu de Arqueologia e Etnologia, Universidade de São Paulo, São Paulo, Brazil
  • Department of Biology and Center for Energy, Environment and Sustainability, Wake Forest University, Winston-Salem, NC 27106, USA
  • Florida Institute of Technology (US)
Venue
Proceedings of the Royal Society B: Biological Sciences
Published
2014-02-22
Volume
281
Issue
1777
Pages
20132475
ISSN
  • 0080-4649 (ISSN-L)
  • 0962-8452
  • 1471-2954
OpenAlex
W2111058040
Cited by
179
References
70
Citations by year
2026: 7 · 2025: 7 · 2024: 5 · 2023: 16 · 2022: 10 · 2021: 17 · 2020: 26 · 2019: 15 · 2018: 20 · 2017: 15 · 2016: 19 · 2015: 19 · 2014: 3
FWCI
353.22
Type
journal article
Language
en
Open access
Locations
  • Proceedings of the Royal Society B Biological Sciences (publishedVersion)
  • Europe PMC (PubMed Central) (publishedVersion)
  • PubMed Central (publishedVersion)
  • PubMed (publishedVersion)
  • University of New Hampshire Scholars Repository (University of New Hampshire at Manchester) (submittedVersion)
Topics
  • Social Sciences › Arts and Humanities › History › Amazonian Archaeology and Ethnohistory
  • Life Sciences › Agricultural and Biological Sciences › Soil Science › Soil and Environmental Studies
  • Social Sciences › Archeology › Archaeology and ancient environmental studies
Keywords
terra preta, pre-Columbian societies, anthropogenic soils, Amazon basin, maximum entropy, environmental predictors, site fidelity, Amazonian rivers
MeSH terms
Algorithms, Archaeology, Environment, Soil, South America

About these checks

Registry, retraction, Cites and statistics results are computed, not judged, with one exception: a printed reference that no index lists is read once by a model before it counts as a citation error. Claims are extracted by a model and kept only when their quote appears verbatim in the text; each cited source is then checked, with a model’s help, for whether it says what the claim relies on. Those verdicts can be wrong — read the claim’s quote and the cited source before relying on one.

A language model drew the claims from the paper on 2026-11-10, under version 3 of the claim definition (model deepseek-v4.1-flash, prompt extract-v3).

A second model labelled each claim on 2026-11-10 (model jev-1.13-20260917, definition revision gold-guideline-v0.2).

Cited sources are checked with a language model’s help (gpt-6-sol).

Statistics and arithmetic are recomputed, not judged.

Confidence bands are shown only for fields calibrated on our annotated test set. None is calibrated yet, so no band is shown.

What counts as a claim ›How we measure confidence ›How we check this ›

Are you an author, or do you see a problem with this page? Request a review