Taxonomic and environmental significance of Poaceae and Cyperaceae phytoliths from the Northern Territory, Australia

Abstract

Phytoliths are a valuable tool for reconstructing past grassy ecosystems. However, they are not commonly utilised as a palaeoecological proxy in Australia due to a lack of modern reference material from plants, particularly grasses. This study analyses phytolith reference material from 49 grass and 4 sedge species from the Northern Territory, Australia. This is used to develop a detailed classification scheme and multivariate morphospace analysis to examine taxonomic and ecological patterns of grass silica short cell phytolith (GSSCP) production within the Poaceae (grass) family. The results of detrended correspondence analysis show that grass subfamilies, tribes, and genera in this region can be differentiated through phytolith assemblages, and that these assemblages reflect the environmental conditions associated with various grass taxa. The developed detailed classification system and examination of co-occurrence patterns reduces redundancy of phytolith morphotypes across subfamilies, improving taxonomic and palaeoecological resolution of phytolith assemblages. Finally, based on the results of this study, a detailed scheme is presented for palaeoecological reconstructions in grassy ecosystems of northern Australia.