Phytolith evidence for the terrestrial plant component at the Lapita Reber-Rakival site on Watom Island, Papua New Guinea

Analysis of phytoliths in sediments from Kainapirina (SAC) locality in the Reber-Rakival Lapita site on Watom Island, East New Britain Province, Papua New Guinea, directly confirms and expands on the types of terrestrial plants, both domestic and natural, identified in the cultural and ashfall deposits of c. 400 cal. B.C. to A.D. cal. 650 found at the site. A significant new finding is that evidence for banana cultivation throughout that period can be associated with both former and additional confirmatory evidence for the growing of coconut and Canarium nut trees plus a range of new plants. Gardening activity alternating with fallow is also strongly suggested by the types of natural tree cover at the conclusion of that occupation sequence and the garden soils lying just below the primary seventh century A.D. Rabaul volcanic ashfall. Taken with the hypothesized existence of pig husbandry, which is based on a previous analysis of faunal remains, as well as information about diet derived from the study of stable isotopes and trace elements present in the human bones from the burials, there is a strong case that arboriculture and horticulture formed a major component of the late-Lapita and immediately post-Lapita economy at this site

Simultaneous extraction of phytoliths, pollen and spores from sediments

Archaeological sediments often offer opportunities to examine local palaeoenvironmental conditions from analysis of included microfossils. On-site conditions commonly vary, and thus so do the preservation conditions for microfossils. Consequently, a range of palynological preparation techniques are commonly used. While different types of microfossils provide valuable palaeoenvironmental information, the use of separate extraction methods for different microfossil types may be both time- and resource-consuming, especially where the recovery predicability is low. This paper examines the possibility of combining preparation techniques for three commonly encountered microfossils—pollen, spores and phytoliths—by comparing pollen extractions using heavy liquid extraction and standard pollen recovery procedures. Although the use of heavy liquids for pollen and spore preparations has been well-documented, for several reasons it has not been a favoured technique for pollen extraction. The research reported here shows that for most of the sediments tested, heavy liquid extraction procedures produced comparable results to those arising from standard pollen extraction techniques. For oxidized sediments, especially, more reliable results are likely to be obtained from heavy liquid extraction procedures than from those employing acetolysis. Overall, heavy liquid procedures allow complementary suites of data to be investigated with the least cost and effort, thus enabling palynologists and phytolithologists to adopt more effective research practices for environmental reconstruction

Collecting starch in Papua New Guinea

Reference entry in Box 6.2, Chapter 6: Reference Collections by Judith Fiel

A comparison of three methods for the extraction of phytoliths from sediments

This paper compares three methods commonly used to extract fossil phytoliths from sediments. A basic procedure using heavy liquid flotation and oxidation is compared with two other procedures across a range of sediment types commonly encountered in archaeological studies. The three procedures are: (1) a heavy liquid flotation method (HLF); (2) a burning method (POW); and (3) another heavy liquid flotation method (HLFPol) similar to HLF, but adapted to allow the extraction of pollen and spores as well as phytoliths, within a single process. Comparisons of the resulting output using these three techniques for phytolith extraction show that different methods can produce different results, and therefore basic techniques should be modified according to the characteristics of the sediments for which they are used. While all the techniques showed similarities in assemblage results, there were problems associated with disaggregation and effective separation of light and heavy fractions, in particular with the POW procedure. The evidence suggests that morphotype selection occurred both within the physical sorting process and in the process of inverting slides to shed excess residue; in both cases it is difficult to suggest a solution to the problem. The results show clearly that the advantages gained by using the POW procedure are largely outweighed by the problems encountered with its use, and because of possible size/shape selection, it is not recommended for general extraction procedures. The heavy liquid flotation procedures, on the other hand, are shown to produce more concentrated residues with higher levels of clarity and less potential than the POW procedure for sample bias. The use of a non-toxic heavy liquid, sodium polytungstate, now allows the process to be used in relative safety. It is recommended that analysts use heavy liquid flotation procedures with chemical treatments specific to sediment requirements

An assessment of techniques for the deflocculation and removal of clays from sediments used in phytolith analysis

This paper describes an experiment in which a comparison is made between two techniques of deflocculation and clay removal generally used for palynological extraction. In the experiment, methods used commonly for pollen extraction are applied to phytolith extraction. The palynological products of the different preparation techniques are compared by reference to several attributes: the time and efficiency in the preparation method; the weight of residue resulting from each method; the palynological composition; clarity of the palynomorphs on the slides; and measures of differential loss and selection by palynomorph shape and size. The results are compared and discussed in relation to the still-settling technique which is most commonly used for phytolith extraction. It is concluded that centrifugation is a reliable and fast method that can be used to remove clays from fine-grained sediments for the extraction of phytoliths and other silica microfossils. High levels of diversity were recorded for morphotypes across all size classes. It produced superior results to the sieving technique and there is no reason to assume that it cannot beused to produce results comparable with still-settling if calculations of settling times consider the implications of sediment density on fluid viscosity. Adoption of the centrifugation method for clay removal from palynological sediment samples can greatly reduce extraction times and, therefore, it is a recommended procedure