A “Dirty” Footprint: Anthropogenic Soils Promote Biodiversity in Amazonian Rainforests

Abstract Amazonian rainforests once thought to hold an innate pristine wilderness, are increasingly known to have been densely inhabited by populations showing a diverse and complex cultural background prior to European arrival. To what extent these societies impacted their landscape is unclear. Amazonian Dark Earths (ADEs) are fertile soils found throughout the Amazon Basin, created by pre-Columbian societies as a result of more sedentary habits. Much is known of the chemistry of these soils, yet their zoology, have been neglected. Hence, we characterised soil macroinvertebrate communities and activity in these soils at nine archaeological sites in three Amazonian regions. We found 667 morphospecies and a tenacious pre-Columbian footprint, with 43% of species found exclusively in ADEs. The soil biological activity is higher in the ADEs when compared to adjacent reference soils, and it is associated with higher biomass and richness of organisms known to engineer the ecosystem. We show that these habits have a unique pool of species, however, the contemporary land-use in ADEs drives nutrient decay and threats biodiversity. These findings support the idea that Humans have built and sustained a contrasting high fertile system that persisted until our days and irreversibly altered the biodiversity patterns in Amazonia.