Phytoliths from native plants and surface soils from the Upper Madeira river, SW Amazonia, and their potential for paleoecological reconstruction

Abstract

Phytolith reference collections of plants and surface soils are a critical part of studies that use these microbotanical remains for archaeological and paleoecological reconstruction. In the archaeologically-rich region of the Upper Madeira river in Rondônia, Brazil, phytolith analysis is being applied in both on- and off-site contexts in order to shed light on human-environment interactions over a period that extends almost the entire Holocene. The present study brings together data on phytolith production patterns among 90 native species, representing 36 plant families, as well as 56 surface soil samples taken from underneath 11 monitored forest plots. Our discussion focuses on the comparison between the surface soil phytolith records and the above-ground floristic inventories, scrutinized considering the plant reference collection results. We found that the phytoliths of several species which produce diagnostic or potentially-diagnostic morphotypes were under-represented in the surface soils, including several understory herbs. While the phytolith assemblages from three forest types (palm, sororoca and dense forest) presented considerable overlap, in accordance with similarities in the floristic inventories, bamboo forest and different types of campinaranas were able to be distinguished based on their phytolith signatures.