A Geographical Method for Anthrosol Characterization in Amazonia: Contributions to Method and Human Ecological Theory

Abstract

This paper focuses on methodological and theoretical aspects of research to characterize the degree of pedological modification of terra preta do índio or Indian Black Earth, a class of anthrosols known in the recent literature as Amazonian dark earths (Woods and McCann 1999). Research was carried out along the Rio Negro, a blackwater region renowned for its oligotrophic (nutrient-poor) status and for the constraints these conditions place on the productivity of terrestrial, aquatic, and human ecosystems. For the blackwater terra firme environments where it is found, Black Earth represents an anomaly both ecologically and culturally. Its high nutrient and soil organic matter (SOM) contents contrast with the characteristics of the highly weathered soils that predominate in the region. Furthermore, both contemporary agricultural practices on Black Earth and the density and/or duration of settlements presumably required to form Black Earth are anomalous for theoretical models that draw strong linkages between specific ecological conditions, shifting agriculture, and low population density in terra firme environments.