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

Abstract

The legacy of pre-Columbian land use in the Amazonian rainforest is one of the most controversial topics in the social^1-10 and natural sciences^11,12. 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 composition in the Amazon, unanswered¹¹. Here, we show that persistent 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 occupation. 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 suggest 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, providing a food production system that sustained growing human populations in the eastern Amazon. Furthermore, these millennial-scale polyculture agroforestry systems have an enduring 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.

Figure 1. Regional Study Area

a. Map showing Amazonian pollen, archaeological site , and records documenting early presence of maize: 1. Lake San Pablo, 2. Lake Ayauch, 3. Lake Sauce, 4. Abeja, 5. Huaypo, 6. Puerto Maldonado, 7. Lake Gentry, 8. Lake Rogaguado, 9. Parmana, 10. Monte Castelo, 11. Geral, 12. Lake Caranã (Supplementary Table S1). 13. Location of Paraíso Cave speleothem record (indicated by star). b. Santarém region showing location of Lake Caranã and the Serra do Maguari archaeological site .

Figure 2

Figure 2 Compiled Data Summary: a, Comparison of relative richness (left) and relative abundance (right) of edible plants (top), edible palms (middle) and other plants from modern vegetation surveys from the three ADE and the three non-ADE sites. b, The phytolith percentage summary diagram of soil profiles (SP), including edible, other trees and herbs, soil charcoal records, and the ADE soil lithology from SDM1 (top). The SPDs from compiled archaeological sites of the Santarém region are also shown (bottom) (Supplementary Table 3). c–d, A summary of the Lake Caranã pollen data (c), the charcoal influx (grey bars) and regime shift index (dashed line) from Lake Caranã (d) and the Paraíso cave speleothem record (e). The age-depth model for Lake Caranã (c–e) is based on calibrated 14C and ²¹⁰Pb dates (Supplementary Table 2). Data in e from ref. .

Figure 3

A conceptual landscape drawing of the changing vegetation and disturbance regimes. The conceptual drawing was inferred from an analysis of pollen, phytoliths and charcoal from the Lake Caranã core and the SMD1 archaeological site associated with the three phases discussed in the main text