Innovation by ancient farmers adds to biodiversity of the Amazon

Date:
June 18, 2020
Source:
University of Exeter
Summary:
Innovation by ancient farmers to improve soil fertility continues
to have an impact on the biodiversity of the Amazon, a major new
study shows.



FULL STORY ========================================================================== Innovation by ancient farmers to improve soil fertility continues to
have an impact on the biodiversity of the Amazon, a major new study shows.


========================================================================== Early inhabitants fertilized the soil with charcoal from fire remains
and food waste. Areas with this "dark earth" have a different set of
species than the surrounding landscape, contributing to a more diverse ecosystem with a richer collection of plant species, researchers from
the State University of Mato Grosso in Brazil and the University of
Exeter have found.

The legacy of this land management thousands of years ago means there
are thousands of these patches of dark earth dotted around the region,
most around the size of a small field. This is the first study to measure
the difference in vegetation in dark and non-dark earth areas in mature
forests across a region spanning a thousand kilometers.

The team of ecologists and archaeologists studied abandoned areas along
the main stem of the Amazon River near Tapajo's and in the headwaters
of the Xingu River Basin in southern Amazonia.

Lead author Dr Edmar Almeida de Oliveira said: "This is an area where
dark earth lush forests grow, with colossal trees of different species
from the surrounding forest, with more edible fruit trees, such as
tapereba' and jatoba'." The number of indigenous communities living
in the Amazon collapsed following European colonization of the region,
meaning many dark earth areas were abandoned.



==========================================================================
The study, published in the journal Global Ecology and Biogeography,
reveals for the first time the extent to which pre-Columbian Amerindians influenced the current structure and diversity of the Amazon forest of
the areas they once farmed.

Researchers sampled around 4,000 trees in southern and eastern
Amazonia. Areas with dark earth had a significantly higher pH and more nutrients that improved soil fertility. Pottery shards and other artefacts
were also found in the rich dark soils.

Professor Ben Hur Marimon Junior, from the State University of Mato
Grosso, said: "Pre-Columbian indigenous people, who fertilized the poor
soils of the Amazon for at least 5,000 years, have left an impressive
legacy, creating the dark earth, or Terras Pretas de I'ndio" Professor
Jose' Iriarte, an archaeologist from the University of Exeter, said:
"By creating dark earth early inhabitants of the Amazon were able to successfully cultivate the soil for thousands of years in an agroforestry system "We think ancient communities used dark earth areas to grow
crops to eat, and adjacent forests without dark earth for agroforestry."
Dr Ted Feldpausch, from the University of Exeter, who co-authored the
study with Dr Luiz Araga~o from the National Institute for Space Research (INPE) in Brazil, said: "After being abandoned for hundreds of years,
we still find a fingerprint of the ancient land-use in the forests
today as a legacy of the pre-Colombian Amazonian population estimated
in millions of inhabitants.

"We are currently expanding this research across the whole Amazon Basin
under a project funded by the UK Natural Environment Research Council
(NERC) to evaluate whether historical fire also affected the forest areas distant from the anthropogenic dark earths." Many areas with dark earth
are currently cultivated by local and indigenous populations, who have
had great success with their food crops. But most are still hidden in
the native forest, contributing to increased tree size, carbon stock
and regional biodiversity. For this reason, the lush forests of the
"Terra Preta de I'ndio" and their biological and cultural wealth in
the Amazon must be preserved as a legacy for future generations, the researchers have said. Areas with dark earth are under threat due to
illegal deforestation and fire.

"Dark earth increases the richness of species, an important consideration
for regional biodiversity conservation. These findings highlight the small-scale long-term legacy of pre-Columbian inhabitants on the soils
and vegetation of Amazonia," said co-author Prof Beatriz Marimon, from
the State University of Mato Grosso.


========================================================================== Story Source: Materials provided by University_of_Exeter. Note: Content
may be edited for style and length.


========================================================================== Journal Reference:
1. Edmar Almeida Oliveira, Ben Hur Marimon‐Junior, Beatriz
Schwantes
Marimon, Jose' Iriarte, Paulo S. Morandi, S. Yoshi Maezumi, Denis S.

Nogueira, Luiz E. O .C. Araga~o, Izaias Brasil Silva, Ted
R. Feldpausch.

Legacy of Amazonian Dark Earth soils on forest structure and
species composition. Global Ecology and Biogeography, 2020; DOI:
10.1111/ geb.13116 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/06/200618120147.htm

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