Abundance Of Phytoliths Research Articles

Issues of phytolith taphonomy at Palaeolithic sites: Investigation and results from Attirampakkam, India

Investigating the taphonomy of phytoliths at open-air archaeological sites is essential for reconstructing past land cover and assessing the plant resources available to hominins, particularly when other indicators (e.g., pollen) are scarce. Here we analyse phytolith abundance and diversity encountered in distinct ‘reservoirs’ at and around the Palaeolithic site of Attirampakkam, South India: (1) in the present-day vegetation (database of 134 species), generating on that basis a fine classification of species-specific phytolith morphotypes; (2) in the topsoil (surface); and (3) at greater soil depths above the archaeological layers (subsurface). We then compare the data to results previously obtained from the deeper underlying archaeological layers. Comparison of the assemblages retrieved from the different reservoirs shows that morphotypes most likely to get carried over from the living plants to the oldest fossil specimens were subsets of herbaceous taxa (Poaceae and Cyperaceae) and a few woody monocotyledons (Arecaceae). The high fidelity of these taxa ranks them among the most reliable for conducting palaeoenvironmental studies at this site, and perhaps more widely in southern India. Provided those taxonomically traceable, non-redundant and non-multiple morphotypes are prioritised over herbaceous dicotyledons and most woody taxa, inferences about environmental conditions and changes at the time of hominin occupation during the Pleistocene can be made with a fair margin of confidence.

The earliest burst of necrophagous dung beetles in South America revealed by the Cenozoic record of Coprinisphaera

New ichnological, sedimentological and palaeobotanical information from a Miocene palaeosol succession from Patagonia bearing abundant fossil brood balls of dung beetles (Coprinisphaera) allow inferring novel aspects of the evolutionary history, biology and feeding habits of Scarabaeinae, along with the palaeoenvironmental and palaeoclimatic conditions in which they nested. Coprinisphaera tonnii and Coprinisphaera akatanka, both attributed to necrophagous dung beetles, represent 40.2% of the specimens. Considering their scarce or null record in older Cenozoic units from South America, these high values reveal that the first burst of necrophagous Scarabaeinae took place during the Miocene. Some Coprinisphaera preserve characters that indicate the developmental stage of the ball occupant and the adult emergence success. Both ichnospecies show the egg chamber isolated from the provision chamber, which was associated with a higher preference of cleptoparasites for necrophagous balls. The comparison among the abundance of traces of nest intruders in Coprinisphaera attributed both to necrophagous and to coprophagous beetles from different units of South America indicates that the presence of such intruders would be independent of the nature of the organic matter contained within the balls. Phytolith analyses performed in Coprinisphaera and extant necrophagous and coprophagous balls indicate that the comparison between the relative abundance of phytoliths in the wall of the brood ball, their infilling and the bearing palaeosol is a useful tool for inferring the feeding behaviour of the trace makers and support the attribution of Coprinisphaera tonnii and Coprinisphaera akatanka to necrophagous Scarabaeinae. Sedimentary and palaeosol analyses indicate that the beetles would have nested in well-drained soils showing mollic-like features, in grass-dominated habitats, under a seasonal sub-humid, temperate–warm climate.

Opaline phytoliths in Miscanthus sinensis and its cyclone ash from a biomass-combustion facility

Classifying biofuel feedstock crops on the basis of their inorganic constituents is needed to evaluate the critical role these components play during combustion and, later, when the ashes are used as fertilizer or as secondary raw material. Fluorescent and white-light microscopy, in combination with environmental scanning electron microscopy and energy-dispersive X-ray spectroscopy, was used to characterize phytoliths in Miscanthus sinensis, its dry extracts, and in the cyclone ash produced by the semi-industrial (400 kW) burning of this energy crop. The results show that the phytoliths are made of opal, SiO2•n(H2O). X-ray powder diffraction data document that the SiO2-rich (31.7 wt%) cyclone ash consists of nearly 83 wt% amorphous material, which reflects the abundance of phytoliths in the studied materials. The cyclone ash also contains high amounts of some heavy metals, which suggests that Miscanthus sinensis is suitable for bioremediation of contaminated soils.

Early Middle Ages Houses of Gien (France) from the Inside: Geoarchaeology and Archaeobotany of 9th–11th c. Floors

ABSTRACTAt Gien (France), indoor floors from early Middle Ages occupation (8th–10th c. AD) are very well preserved, providing a new reference for archaeological investigation in northern France. This site is located on an outcrop, 20 m above the Loire valley, where a 15th c. castle stands now. The medieval occupation combines high-status houses with crafting and agricultural areas. They constitute a new urban nucleus, which grew 2 km east from an ancient Roman settlement. During the rescue excavation, four buildings of different status were sampled and studied using an integrated approach, combining stratigraphy, micromorphology, chemical, macro-remain and phytolith analyses. Micromorphological investigations helped to identify 74 built floors, from 0.5 to 150 mm thick, made with transformed local clay or imported silty earth. Mineral floors were covered by vegetal ones, consisting of crop processing refuse. These litters include an abundance of phytoliths and some seeds, both produced by cultivated cereals, which were processed in situ, such as Triticum durum, Secale cereale and Hordeum vulgare. The refuse above the mineral and vegetal floors were trampled. They were produced not only by domestic activities, such as cooking and eating, but also by metallurgic activities and animal husbandry. The investigation of a contemporary pit indicated that, despite the large amount of refuse, floors were well maintained and regularly rebuilt. The spatial distribution of waste indicated that a single space could be dedicated to several activities, which were not necessarily separated by new floors. Moreover, the total absence of bioturbation allowed the study of a stage of dark earth formation, by comparing it to the contemporaneous mechanical disturbance of a part of the strata which occurred when building new floors. All these results give new evidence of the richness and the complexity of the early Middle Ages town, in addition to help identifying the activities which could take place in early castral areas.

Multi-proxy evidence for an arid shift in the climate and vegetation of the Banni grasslands of western India during the mid- to late-Holocene

Tropical semi-arid grasslands are a widespread and ecologically and economically important terrestrial biome. Here, we use paleoecology to understand woodland–grassland transitions across the mid- to late-Holocene period in the Banni grassland, western India. Multi proxy analyses involving palynology, phytoliths and elemental geochemistry were carried out on two sediment cores retrieved from wetlands (Chachi and Luna), to understand temporal fluctuations in vegetation, moisture availability and other environmental parameters. Based on the results, the Chachi core was divided into two major climatic phases. Phase 1 (4600–2500 cal. yr BP) was characterised by high precipitation and abundance of pollen types and phytolith morphotypes that indicate the presence of woody savanna, and mesic herbaceous taxa. Phase 2 (2500 cal. yr BP to the present) was characterised by lower precipitation, lower abundance of mesic taxa and an increase in grass phytolith abundance. However, the period from ~1000 cal. yr BP to the present was characterised by the increased abundance of leguminous taxa, dryland herbs/shrubs and a decline in grass phytolith abundance. The Luna core (~1000 cal. yr BP to the present) also showed results matching with the Chachi core for this latter period. Overall, moisture availability in the ecosystem appears to have declined since 4600 cal. yr BP, and the vegetation has responded to this. Although the balance between tree, shrub and grass elements has fluctuated, overall, the region has remained as an open ‘grass and shrub savanna’ with sparse woody vegetation throughout this period. Our study provides insights into the vegetation dynamics and environmental settings in a poorly understood tropical arid-grassland ecosystem from Asia during the mid-late-Holocene.

Light Environment and Epidermal Cell Morphology in Grasses

Premise of research. Phytoliths (bio-opal) of grasses are preserved in the fossil record and constitute the best method to study grasses and grassland evolution in deep time. However, methods currently used to reconstruct habitat openness based on grass phytolith abundance are potentially biased because of the prolific production of phytoliths in grasses compared to other plants, both herbaceous and woody (ferns and dicots). On the basis of relationships observed in eudicot epidermal cells, we hypothesized that the shape (undulation) and size of epidermal cells (and phytoliths derived from them) will vary with irradiance. This variation could be used to develop a proxy for habitat openness in the fossil record.Methodology. We grew five species of grass under four irradiance levels and measured epidermal cell parameters, including undulation, area, length, and width, along with gross leaf morphology.Pivotal results. ANOVA statistical tests showed that with the exception of the shade-adapted Chusquea, the g...

Dental calculus evidence of Taï Forest Chimpanzee plant consumption and life history transitions.

Dental calculus (calcified dental plaque) is a source of multiple types of data on life history. Recent research has targeted the plant microremains preserved in this mineralised deposit as a source of dietary and health information for recent and past populations. However, it is unclear to what extent we can interpret behaviour from microremains. Few studies to date have directly compared the microremain record from dental calculus to dietary records, and none with long-term observation dietary records, thus limiting how we can interpret diet, food acquisition and behaviour. Here we present a high-resolution analysis of calculus microremains from wild chimpanzees (Pan troglodytes verus) of Taï National Park, Côte d’Ivoire. We test microremain assemblages against more than two decades of field behavioural observations to establish the ability of calculus to capture the composition of diet. Our results show that some microremain classes accumulate as long-lived dietary markers. Phytolith abundance in calculus can reflect the proportions of plants in the diet, yet this pattern is not true for starches. We also report microremains can record information about other dietary behaviours, such as the age of weaning and learned food processing techniques like nut-cracking.

Grass inflorescence phytoliths of useful species and wild cereals from sub-Saharan Africa

Dendritic phytoliths that precipitate in grass inflorescences are often used in archaeology to trace the use of cereals (i.e. grasses harvested for their edible grain) and their domestication by early human societies. High amounts of these morphotypes are sometimes interpreted in terms of cereal accumulation in archaeological contexts. In sub-Saharan Africa, few cereals were domesticated during the mid-Holocene, but many wild grasses are still largely harvested by modern societies for food. The harvesting of wild cereals is also considered as one of the first stages toward early grass domestication. To evaluate how well dendritic phytoliths and/or other phytoliths produced in the grass inflorescences could help trace the use of wild cereal grains in sub-Saharan Africa, we analyzed the phytolith content of 67 African species (including 20 wild cereals), and 56 modern soils. We used test-value analysis and ANOVA to evaluate how well grass inflorescences could be distinguished from leaf/culm parts based on their phytolith content. We also measured the abundances of these phytoliths in natural soils from sub-Saharan Africa to provide a benchmark percentage abundance above which anthropogenic accumulation may be suspected in archaeological deposits. Our results confirm that, although rondel type phytoliths are abundant, only the dendritic phytolith morphotype is exclusive to the grass inflorescences. Yet, dendritic phytoliths do not occur in all species. They happen to be most frequent and found in greatest abundance (>34% relative to total phytolith count) in Panicoideae grasses (Sehima ischaemoides, Sorghastrum stipoides, and Sorghum purpureo-sericeum), and in one Eragrostideae species (Eragrostis squamata), which are not considered cereals. Inflorescences of the wild African cereals studied here do not happen to be particularly rich in dendritics (<7% in average). Finally, dendritics are rare in modern natural soils (<1% relative to total phytolith count, <3% relative to sum of grass silica short cells plus dendritics), even under stands of rich dendritic producers. We conclude that dendritic phytoliths may be used for tracing remarkable deposits of grass inflorescences at archaeological sites in sub-Saharan Africa, but are not exclusive to domesticated or wild cereals. Abundances of dendritics >>3% relative to sum of grass silica short cell phytoliths plus dendritics are likely to indicate anthropogenic accumulation of grass inflorescences. Yet, the absence or low abundance of dendritic phytoliths in archaeological deposits may not always indicate the absence of anthropogenic accumulation of grass inflorescence material.

Detecting ancient wild rice (Zizania spp. L.) using phytoliths: a taphonomic study of modern wild rice in Minnesota (USA) lake sediments

Wild rice (Zizania spp. L.) is a North American native grain with spiritual and dietary significance to many native people. Wild rice is also an important aquatic plant that provides critical habitat to wetland and aquatic wildlife. Past distribution of wild rice in North America is poorly understood, largely because of the limited taxonomic resolution of Poaceae pollen. A novel technique for detecting diagnostic Zizania silica phytoliths allows unambiguous identification of this taxon in lake sediments. We need to better understand modern depositional patterns of phytoliths in lake sediments, however, before attempting detailed paleoreconstructions. We analyzed distributions of diagnostic Zizania and other Poaceae phytoliths in modern sediments from three lakes with variable percent cover of wild rice and a non-wild rice control lake in central Minnesota. Absolute counts of phytoliths per gram sediment were achieved using an exotic diatom marker. Non-Zizania short-cell phytoliths, i.e. phytoliths from wetland grasses Phragmites australis and Muhlenbergia glomerata, dominate the assemblages in all lakes. Most Poaceae short-cell phytoliths appear to be derived locally, with little evidence for regional inheritance from eolian or alluvial processes. Because of anatomical differences in decay of plant debris and other taphonomic issues, Zizania inflorescence rondel phytoliths were most abundant, with morphotypes from other parts rarely encountered. Even in sediments under the densest wild rice stands, Zizania phytoliths contributed a maximum of 9 % to total Poaceae phytolith abundance. Lake morphology also affects the depositional pattern of phytoliths in modern sediments, so coring locations should be considered carefully. At least 500 phytoliths should be counted to detect a sufficient number of wild rice phytolith morphotypes. Diagnostic Zizania phytoliths are a reliable tool for wild rice detection in paleolake sediments.

Phytoliths from the coastal savannas of French Guiana

Phytolith reference collections are a fundamental prerequisite for accurate interpretation of fossil phytolith assemblages used in reconstructing vegetation histories. As part of a multi-disciplinary research project studying Late Holocene landscape transformations associated with pre-Columbian raised field complexes in the coastal savannas of French Guiana, phytolith production in selected plant species with high environmental and economic significance native to the region was examined. A total of 49 families, 92 genera, and 108 species were analysed. Phytolith abundance in each specimen was rated qualitatively and morphotypes described following modern standards of nomenclature. Of the 92 non-Poaceae species tested, 37 contributed phytoliths that are diagnostic to at least the family level. Two of these are newly-discovered phytolith morphotypes isolated from Protium guianense (Burseraceae) and Thelypteris confluens (Thelypteridaceae [Pteridophyta]) which have not been described previously. This work represents the first systematic undertaking to establish a phytolith reference collection of French Guiana flora. Results reinforce the usefulness of phytolith analysis for distinguishing ecologically significant taxa, and therefore major vegetation formations. The creation of a comprehensive reference collection for French Guiana improves taxonomic resolution and has provided the necessary ground work for the interpretation of palaeoevironmental and archaeological records in the region.

Water-level variations in Lake Nhauhache, Mozambique, during the last 2,300 years

Stratigraphic variations in diatom composition and phytolith abundance in a sediment core from a small, hydrologically isolated waterbody, Lake Nhauhache, Mozambique, provide evidence of water-level fluctuations over the past ~2,300 years. Ten AMS radiocarbon dates on bulk sediment samples show that the lake came into existence about 2,300 years ago and that it has dried out since then, but only for brief time periods. Changes in the diatom assemblage composition indicate that lake level fluctuated in response to shifting humidity conditions. The changes reflect wetter conditions ca. 300 BC–AD 800, more variable conditions between AD 800 and 1150, a distinct dry phase within the time span AD 1150–1700 and a return thereafter to more humid conditions until present. There is general agreement between the Lake Nhauhache record and other records from the Southern Hemisphere summer rainfall region. This suggests that sediments from small interdunal lakes, which are abundant along the coast of southern Africa, provide reliable, regional paleoenvironmental information about an area from which more such data are needed.

Elemental composition of phytoliths in modern plants (Ericaceae)

Plants accumulate opaline silica in the form of phytoliths. Species and availability of Si are the main factors that determine the phytolith content in plants. Therefore, several Ericaceae species were tested in different soils. Erica andevalensis is restricted to grow in acid- and metal-enriched soils in the Iberian Pyritic Belt, and therefore it is particularly suitable to study the effects of metals on the phytolith composition. Ericaceae that originate from soils in mining areas were compared with those from unpolluted areas. Species from mining areas included E. andevalensis (Riotinto mines, Andalucía, SW Spain), Erica australis and Calluna vulgaris (Touro mine Galicia, NW Spain). For the unpolluted areas, C. vulgaris was collected on peat (Sapric Histosol), quartzite (Albic Podsol) and serpentinite (Mollic Gleysol) soils. The abundance and elemental composition (Ca, Mg, Al, Fe, Mn, Cu, Zn, Cr, Ni, Pb and As) of phytoliths in leaves were analyzed. Elemental quantification by means of Energy-dispersive Miniprobe Multielement Analyzer (EMMA-XRF) is an innovative method for elemental analysis of phytoliths. Both the highest leaf phytolith production and elemental concentration were found in species from mine soils, with the highest phytolith contents for C. vulgaris and highest concentration of elements (Ca, Fe, Mn, Cu, Zn, Pb and As) for E. andevalensis. The highest Cr and Ni concentration in phytoliths was found on serpentinite soils. The lowest values of phytoliths and metal concentrations were found in heathers from quartzite and peaty soils.The abundance of phytoliths agreed with the availability of Si in the studied soils and its elemental composition reflected the geochemical conditions. The results presented here suggest that phytoliths act as alleviates of metal stress in heathers.

Taphonomy of phytoliths and macroplants in different soils from Olduvai Gorge (Tanzania) and the application to Plio-Pleistocene palaeoanthropological samples

The abundance and types of phytoliths in the fossil record are taphonomically biased and do not correspond with the macroplant record. To better understand the bias and improve the interpretation of samples from Olduvai Gorge, Tanzania, we analysed the phytoliths from three sample sets: modern grasses, sedges, palm and dicots in the area; modern soils in the area; and the fossil soils from the eastern palaeolake margin in lowermost bed II. Fourier transform infrared spectrometry analyses were performed in parallel to compare the mineral composition of both modern soils and fossil soils. We found that the abundance of phytoliths is greatly reduced in soil samples compared with modern plant material, but the morphotypes can be reliably interpreted. Dicotyledonous wood/bark phytoliths appear to be over represented in the soil types. Grass phytoliths, and sedges to a lesser degree, are preserved in the soils but in lower abundances resulting in these groups being under-represented. The macroplant fossils are fragments of grass and sedge aerial culms, and dicotyledonous stems that are preserved in fluvial and lacustrine deposits. It is suggested that phytoliths represent the continuous flora whereas macroplant fossils represent the more robust tissues of selected plants preserved under more catastrophic conditions. A post-depositional model is proposed and the palaeovegetation is reinterpreted as being richer and more complex than indicated by other fossil data.

Geochemistry (δ 13C, δ 15N, 13C NMR) and residence times ( 14C and OSL) of soil organic matter from red-brown earths of South Australia: Implications for soil genesis

Soil forming processes important to the development of Red-Brown Earths (duplex soils) in southeastern Australia have been investigated by a combination of techniques, including isotopic (δ 13C, δ 15N, 14C), spectroscopic ( 13C NMR, MIR), optically stimulated luminescence dating (OSL) and phytolith analyses. A distinct increase in clay content, corresponding changes in the abundance of major elements, as well as changes in organic chemistry ( 13C NMR), stable isotope trends (δ 13C, δ 15N), and phytolith abundance, are apparent in the transition from the very sandy A horizon to the clayey B horizon in three soil profiles from the Coonawarra–Padthaway region of South Australia. These structural and chemical changes between the A and the B horizons are associated with an abrupt increase in both 14C (bulk soil organic matter) and OSL burial ages of individual quartz grains. While previous interpretations have promoted the formation of duplex red-brown earths as due to clay illuviation, we propose a two-stage soil formation, which may be related to paleoclimatic changes during and after the Last Glacial Maximum. Our data suggest that a major part of the A horizon was aeolian derived and was deposited over the last 10,000 years, whereas much of the B horizon, although originally aeolian, has been extensively modified over much longer periods of time (tens of thousands of years). These results indicate the influence of different substrates (sandy versus clayey), process and time for formation as well as paleoclimatic history on the physical properties of the soil and the chemical characteristics of the organic matter within the soil profile.

Recent and abrupt environmental change in the Florida Everglades indicated from siliceous microfossils

We used paleoecological methods to infer environmental conditions in Water Conservation Area 2A (WCA-2A) of the Everglades before impoundment in 1961, and we compared pre-impoundment environmental conditions to present conditions. Abundances of siliceous microfossils (diatoms, chrysophyte cysts, sponge gemmoscleres, and plant phytoliths) were analyzed in two sediment cores from nutrient-enriched northern WCA-2A and in two sediment cores from unenriched southern WCA-2A. Nutrient enrichment in northern WCA-2A after 1961 was associated with an increasse in relative abundance of eutrophic diatoms. A pH increase in much of WCA-2A after 1961 was indicated by a decrease in relative abundance of acidic indicators (Eunotia diatoms and the sponge Anheteromeyenia ryderi) and a decrease in richness of chrysophyte cysts. An increases in anoxia in nutrient-enriched northern WCA-2A, during about 1961–1980 when high water depth was maintained, was suggested by an increase in visible dissolution of silicenous microfosils. A decreases in palm phytolith abundance after 1961 and lack of recovery after water depth was lowered suggest either that water depth is still maintained high enough to adversely affect vegetation or that there has been insufficient time for recovery. Numbers of sponge gemmoscleres decreased to less than 1% of preimpoundment numbers, suggesting that there has been a dramatic decrease in sponge abundance. The environmental changes discovered in this study suggest directions for future management of of the Everglades.

The occurrence of phytoliths in the reproductive structures of selected tropical angiosperms and their significance in tropical paleoecology, paleoethnobotany and systematics

The reproductive structures of tropical angiosperms contribute an abundance of phytoliths. Silica bodies are often completely distinct in structure and surface sculpture from those derived from vegetative organs, appear to be little influenced by environmental variables and are most useful for the classification of taxa at the level of genus and possibly species. This paper provides a survey of the occurrence and morphology of phytoliths in the fruits, seeds and inflorescence bracts of tropical angiosperms. It assesses their significance in tropical paleoecology, paleoethnobotany and systematics.