A "Dirty" Footprint: Anthropogenic Soils Promote Biodiversity in Amazonian Rainforests

Amazonian Dark Earths(ADEs) are fertile anthropicsoils found throughout Amazonia, resulting from long-term occupation by pre-Columbian societies. Although the chemistry of these soils is well known, their biodiversity, particularly soil invertebrate communities have been neglected. To address this, we characterised soil macroinvertebrate communities and their activities in ADEs, comparing them with adjacent reference soils under forests and agriculture, at nine archaeological sites. We found 667 morphospecies and a tenacious pre-Columbian biodiversityfootprint, with 40% of species found exclusively in ADEs. Soil biological activity was higher in ADEs than in adjacent soils, and associated with higher biomass and richness of organisms known to engineer the ecosystem. We show that these habitats have unique species pools, but that contemporary land-use causes nutrient loss and threatens their diversity. Both past and present human activities alter biodiversityand its distribution in Amazonia, and further efforts are needed to recognize and preserve these ADEs and their biodiversity.