Starch grains and environmental reconstruction: a modern test case from West New Britain, Papua New Guinea

The analysis of starch grains preserved in sediments as a technique for palaeoenvironmental reconstruction is an important new technique, but the limits of inference using this methodology still need to be assessed. A morphological classification of starches extracted from topsoils collected from a range of modern environments in the humid tropical region of Papua New Guinea was therefore conducted to see if discrimination among plots with different vegetation could be achieved. Using an assemblage-based approach, starch grains, initially classified into morphological categories and re-organized into groups according to size/shape frequency distributions, were grouped using principal components analysis. The results correctly identified different types of human land use and provided good discrimination between gardens and forest. These preliminary results show that past human land use can be satisfactorily reconstructed using multivariate analysis of starch grain assemblages with only data on size and morphology to characterize the grains. The findings of the starch study compared favourably with a phytolith analysis of material from the same locations, although the two microfossils target different plant groups. Whereas phytoliths discriminate among different levels of disturbance, starch grains can add information about specific site function, an important consideration especially for regions where plant staples are typically high-starch producers. Combining starch grains and phytoliths in future studies will enhance the accuracy of palaeoenvironmental reconstructions.