Phytoliths in the Flora of Ecuador: Establishing Vegetation Signatures and a Key to Diagnostics

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With National Science Foundation support, Dr. Deborah M. Pearsall and colleagues at the University of Missouri will continue basic research into the nature of phytolith production in the flora of Ecuador. Over the past 30 years, phytoliths-microscopic silica bodies produced in plant tissues-have contributed to our understanding of human-landscape interactions in the New World tropics. Phytoliths extracted from naturally accumulating sediments, such as those that build up in lakes, provide a detailed record of past vegetation, and the impact on vegetation of human activities such as cutting of forests for agriculture. Phytoliths recovered from prehistoric villages and ancient agricultural fields provide equally valuable information on human uses of plants for foods, and in ritual and medicine. Successful tapping of the wealth of information provided by these durable plant microfossils is dependent on discovering phytoliths that can be used to identify key wild species and economic plants. Advances in this area were made in the first phase of the project (August 1997 to December 2000). Forest species critical for interpreting vegetation change and stability in tropical lowland settings were found to produce distinctive phytoliths, and new approaches for identifying crops such as corn were developed.The new project builds on these advances. First, Pearsall and student assistants will study phytolith production in plants remaining from the original project, and add all new diagnostic phytoliths to the University of Missouri database. Work will then begin on establishing phytolith vegetation "signatures" for plant communities in Ecuador, from Pacific coast to the Amazon, and along the coast from the dry forests of the south to the humid northern lowlands. Two colleagues will join Pearsall for this effort, Dr. Robert Benfer, an expert in multivariate statistical analysis, and Dr. Robin Kennedy, botanist and ecologist. The research team will analyze patterns of diagnostic phytoliths recovered from comparative soil samples from across Ecuador, and develop descriptive and statistical ways of identifying vegetation types (dry tropical forest, evergreen forest, etc.) from the combinations of phytoliths in the soil. The final stage of the project focuses on making the primary results, new phytolith types and vegetation signatures, accessible and useable by other researchers. An interactive, web-based identification aid to phytoliths produced by New World tropical plant species will be tested.Phytolith analysis is a young discipline in archaeology (modern studies date to the 1970s), and as such much basic research remains to be accomplished. This study will advance our knowledge of phytolith production in diverse plant families and vegetation types. The intellectual merit of the project also lays in future applications of the results of the research, for example, to questions of the origins and evolution of agriculture in the New World, and the nature and sustainability of tropical forest agriculture. The broader impacts of the study are that researchers working in regions throughout the New World tropics will find the phytolith vegetation signatures, database of diagnostic phytoliths, and prototype key useful. Web-based dissemination of results will broaden the access of researchers and students based in Ecuador and other Latin American nations to advances in phytolith research methods and approaches.