Widespread reforestation before European influence on Amazonia

Abstract

An estimated 90 to 95% of Indigenous people in Amazonia died after European contact. This population collapse is postulated to have caused decreases in atmospheric carbon dioxide concentrations at around 1610 CE, as a result of a wave of land abandonment in the wake of disease, slavery, and warfare, whereby the attendant reversion to forest substantially increased terrestrial carbon sequestration. On the basis of 39 Amazonian fossil pollen records, we show that there was no synchronous reforestation event associated with such an atmospheric carbon dioxide response after European arrival in Amazonia. Instead, we find that, at most sites, land abandonment and forest regrowth began about 300 to 600 years before European arrival. Pre-European pandemics, social strife, or environmental change may have contributed to these early site abandonments and ecological shifts.

Population Histories and Genomic Diversity of South American Natives

“…Notably, an additional bottleneck was inferred for the Tupí, starting at ∼37 gBP (∼1036 BP) before contacting Europeans and happening up to ∼15 gBP (∼420 BP). This population decline agrees with a previous report based on Amazonian fossil pollen analysis, which pointed to an expansion of the Amazon forest, a proxy for human population decline, at approximately 300–600 years before the European arrival ( Bush et al 2021 ). However, the inferred time for the population collapse might be influenced by differences in the generational interval; a new study ( Coll Macià et al 2021 ) inferred that South American lowlanders have the shortest generation intervals in the Americas, which could ultimately translate into older dates for inferences based on the number of generations, including the inference of older population collapse dates from the size distribution of IBD segments.…”

Soil Quality Restoration during the Natural Succession of Abandoned Cattle Pastures in Deforested Landscapes in the Colombian Amazon

“…Changes in the quality of Amazon soils associated to land use changes have been assessed by soil chemical indicators [43][44][45], soil physical indicators [43], soil biological indicators [46][47][48][49] and combinations of soil variables [33,41,48,49]. Pasture, as the most intense land use change, presents the most dissimilar conditions among other land uses, such as its microbial composition [50] and microbial activity [51].…”

Contradicciones de la Amazonía en el Brasil: Una nueva perspectiva

“…La Amazonía brasileña es también el hogar de una riqueza cultural, incluyendo el conocimiento tradicional asociado al patrimonio genético y la forma de utilizar los recursos naturales sin agotarlos o destruir el hábitat natural [25]. La Amazonía pudo tener una población de 4 a 5 millones de habitantes a la llegada de los europeos en 1492; hoy, no pasan de 900.000 habitantes [26].…”

“…El grado de deforestación en la Amazonía en Brasil, se ha convertido en una amenaza de tal dimensión para el equilibrio del ecosistema y su megabiodiversidad, problemática ampliamente registrada en varios estudios [1][2][3]19,26]. Según el PRODES-Amazônia [42], los datos de intervención antrópica (deforestación seguida por quema) abarcaron en el 2019, para el Estado de Pará-Brasil, 271862.57 km 2 , Mato Grosso 218741.90 km 2 , Maranhão 106510.04 km 2 , Rondônia 94767.13 km 2 , Amazonas 41895.57 km 2 , Tocantins 30663.63 km 2 , Acre 24033.01 km 2 , Roraima 11311.12 km 2 y Amapá 3112.88 km 2 [42].…”