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Rice is among the world’s most important and ancient domesticated crops. However, the spatial and temporal pattern of the early rice domestication process remains unclear due to the lack of systematic study of wild/domesticated rice remains and corresponding dates during the early Holocene. Here, we collected 248 samples from five typical Shangshan cultural sites in the lower Yangtze region where is the most likely origin place of rice for phytolith analysis. The results showed the following. (1) Rice bulliform phytoliths from the five sites all present domestication traits, suggesting that the rice domestication process had begun across the region by the early stage of the Holocene. (2) The relative domestication rates reflected by the rice bulliform phytoliths were different between sites, the sites with higher domestication rates were distributed closer to the mainstream river. (3) The rice domestication process revealed by bulliform phytoliths can be divided into three periods during the early Holocene: from 10 to 9 ka, rice domestication began and stayed at a low level under 35%; from 9 to 8.5 ka, rice domestication level increased to 50%; and from 8.5 to 8 ka, rice domestication level was in a fluctuating state. (4) By 9 ka BP, rice double-peaked phytoliths from glume cells are present in most of the studied sites, which imply the presence of crop dehusking processing. This study reconstructed the spatial and temporal patterns of rice domestication during the early Holocene, which will improve our knowledge of early crop domestication and enhance our understanding of changes in rice status.

Volcanic eruptions can have a significant influence on adjacent ecosystems; however, little is known about the long-term vegetation change related to eruptions. In this study, we examined phytolith records in paleosols at multiple sites in the southern Kyushu District, Japan, to assess the influence of the Kikai caldera eruption 7300 years ago on vegetation. Our results show the vegetational difference before and after the eruption in the study region. Specifically, in the area where the pyroclastic flows distributed more thickly, the original evergreen forest was replaced by Andropogoneae grasslands after the eruption, which has been dominating the landscape in this area for at least 900 years. By contrast, in areas only mildly affected by pyroclastic flows, despite the temporary replacement of forest by grassland, the forest developed and flourished within several hundreds of years of the eruption. This is because a large amount of pyroclastic flow would have devastated all of the vegetation, whereas smaller amounts would have left some untouched forest sites within refugia. Our findings suggest that the vegetation varied significantly depending on the amount of pyroclastic flow reaching the area, even within the pyroclastic flow distributed region.

The El Tigre archaeological site (39°46′49″ S; 62°22′32″ W) is located in the south of Provincia de Buenos Aires, Argentina, on an ancient delta of the Rio Colorado. Its sedimentary sequence shows periods of landscape stability and soil formation processes during the period ca. 1,000–400 years bp. The aim of this paper is to investigate the evolutionary history of the vegetation in order to understand palaeoenvironmental changes during the late Holocene. The study of microremains, mainly phytoliths, from the sedimentary sequence indicates that cold and dry conditions predominated at 2,700–2,200 cal bp, from deposition of non-pedogenetic, aggradational sediments in arid or semi-arid environments and/or sparse vegetation cover. Then the climate became much warmer at ca. 2,200–1,200 cal bp, with greater availability of moisture and the presence of xerophytic shrubs and halophytic grasslands, and also extra-regional trees and shrubs. The records indicate that for ca. 1,500–300 cal bp the climate conditions changed to temperate with periods of greater water availability and the presence of a saline steppe and a greater abundance of Monte-Caldenal scrub vegetation elements. This climatic trend is also in agreement with the soil formation processes defined in the archaeological site sequence. The upper layers of the El Tigre site show lower temperatures in the last 300 years, accompanied by variations in the availability of moisture, with alluvial processes characterized by the presence of saline grasslands with xerophytic shrubs and an increase in Asteraceae and Poaceae, continued by the recent top samples with ruderal communities and sandy grasslands.

International audience; Phytoliths form in plant tissues as fine, silt-sized amorphous silica particles. Once deposited in soils by plant debris, they can dissolve and feed silicon (Si) fluxes to the biosphere and hydrosphere, enhancing the positive effects of Si on plant health and carbon fixation by marine diatoms. In soils, microaggregates (-1): organic matter (50), aluminosilicate mineral (370), iron (Fe) oxide (60), quartz (500) and rice phytolith (20). Models with either amorphous (Am) or crystalline (Cryst) aluminosilicates and Fe-oxides were tested. The Am model included allophane and ferrihydrite while the Cryst model included kaolinite and goethite. Aggregates were visualized by Scanning and Transmission Electron Microscopy. They were compared to individual compounds and unaggregated mixtures through kinetic Na2CO3 and CaCl2 extraction assessing the pools of phytoliths and bioavailable Si, respectively. Aluminum (Al) and germanium (Ge) concentrations, and pH were measured in the CaCl2 extracts. CaCl2 extractable Si decreased in the order (g kg-1): Am mixture (3.72) > Am aggregate (0.95) > Cryst mixture (0.48) > Cryst aggregate (0.39). Aggregation thus reduced Si release by 3.9- and 1.2- fold in the amorphous and crystalline model, respectively. The Si/Al and Ge/Si atomic ratios showed that allophane and phytolith were the main sources of bioavailable Si in the amorphous and crystalline model, respectively. In contrast to the crystalline model (pH 5.0-7.8), the acidic medium in the amorphous model (pH 3.7-4.9) enhanced allophane dissolution. Aggregation thus protected both allophane and phytolith from dissolution, and reduced the release of bioavailable Si, the source of which depended on the component stability and pH.

In combination with published archaeobotanical data, a detailed paleodietary reconstruction is performed here on human teeth (n = 19) using starch grain and phytolith analysis of dental calculus as well as stable isotope ratio analysis of bulk dentinal collagen. The site studied is Xueshan which is a Late Bronze Age (2700–1700 BP) settlement in Yunnan Province, China. Isotopic results show that this population consumed a predominately C3 diet except for one individual that consumed a mixed C3/C4 diet. Starch grains and phytoliths embedded in the dental calculus indicate that a diverse array of plant resources, including C3 cereals (wheat, rice, barley, buckwheat, beans), C4 cereals (millets), and roots and tubers were directly consumed. Comparison of the results presented here with a review of published works on microfossil analysis of human dental calculus from China not only confirms the dietary diversity of Late Bronze Age Yunnan, but also sheds light on the complexity of human-plant food relationships in this region.

International audience; While in tropical soils recycling of plant phytoliths has been shown to represent a major pool of Si available for plants, the main Si pools available for plants in temperate soils are still poorly constrained. We characterised the various Si pools of temperate forested and cultivated soils in France by selecting seven paired sites (adjacent wheat and forest plots) for four soil groups: Luvisols, Albeluvisols, calcaric and hypereutric Cambisols. We showed that CaCl2-extracted Si (bioavailable) is mostly controlled by pH and allophanes (short-range ordered aluminosilicates) but not by phytoliths. Cultivation, by decreasing the soil organic carbon content increases the allophane content and the SiCaCl2 concentration. Our work highlights the importance of allophanes as the missing link between the soil solution and the clay minerals that could explain the reported correlation between the clay mineral content and bioavailable Si.

Mind the Gap: Maize Phytoliths, Macroremains, and Processing Strategies in Southern New England 2500–500 BP. This study presents preliminary results from a phytolith analysis of carbonized food residues and sediment soils from sites in southern New England (Connecticut and Rhode Island) dating 2500–500 BP. Phytolith analyses of carbonized food residues from sites across northeastern North America outside of southern New England demonstrate that maize (Zea mays L.) was introduced to the region as early as 2300 BP, hundreds of years before major shifts in settlement strategies became widespread. Phytolith evidence for maize in eastern North America likewise appears hundreds of years earlier than most maize macroremains, such as kernels, cobs, and cupules, appear. This has puzzled researchers attempting to piece together how maize was first circulated and used in the Eastern Woodlands. Preliminary phytolith analysis of carbonized food residues from seven sites indicates that, consistent with research outside the study area, at least some groups in southern New England cooked maize as early as 2300 BP. The results also indicate that maize cooking practices varied in ways that likely reflect broader subsistence strategies and that may explain the temporal gap between maize phytoliths and maize macroremains.

Reconstruction of grassland ecosystems and their vegetation succession is an important issue in palaeoenvironmental research. Phytoliths and pollen are two common proxies for palaeovegetation reconstruction, and their importance can be evaluated based on investigations of the relationships between modern vegetation and phytolith/pollen assemblages in surface-soil samples. The correlations between phytolith assemblages and environmental variables were analysed based on 34 surface-soil samples from the Xilingol Grassland, Inner Mongolia, North China, and a palynological analysis was carried out on the same samples, enabling a comparison between their sensitivity to vegetation and climate change. The results show that the phytolith assemblages mainly consist of blocky and rondel phytoliths, while other short-cell phytolith types, such as saddle and bilobate types, are scarce. The pollen assemblages were characterised by a high abundance of Artemisia and Amaranthaceae. Canonical correspondence analysis (CCA) indicated that the most important environmental factors affecting the distribution of phytoliths are altitude and latitude, while the mean warmest monthly temperature (MWMT) and altitude were the most significant environmental factors affecting the distribution of the pollen assemblages. CCA of the phytoliths and pollen assemblages separated both samples into two groups: broadleaf forest/scrub and steppe/meadow groups, but it appeared that phytoliths were more sensitive in arid grasslands. This case study could be used as a baseline for interpreting fossil phytolith/pollen assemblages from the grasslands of Inner Mongolia and indicates that multiproxy analysis of the same samples can provide reliable information on palaeovegetation and palaeoclimate reconstruction.

Phytoliths are microscopic particles of amorphous silica produced by plants that have vital importance for environmental change and carbon sequestration. This study investigated phytoliths and their morphotype assemblages, and phytolith-occluded carbon (PhytOC) along a marsh degradation gradient to clarify the significance of phytoliths for evaluating carbon sequestration dynamics during marsh degradation on the Zoige Plateau, China. Soil samples from non-degraded marsh (NDM), lightly degraded marsh (LDM), moderately degraded marsh (MDM), and seriously degraded marsh (SDM) were collected. Soil phytolith shape and PhytOC were determined using heavy liquid suspension, microscope observations, and alkali-solution spectrophotometry. The dominant phytolith morphotypes among the 15 identified in the soils from the differently degraded marshes were lanceolate, rectangular, and elongate, which originated from Poaceae and Cyperaceae. Soil phytolith morphotype assemblages show potential for studying past vegetation and climatic succession in alpine wetlands. The soil phytolith and PhytOC content exhibited no significant differences between the NDM and LDM samples. Compared with the NDM soil, phytolith content was significantly lower in the MDM (33.8–58.8%) and SDM (52.7–65.4%) soils, respectively, and PhytOC content was also significantly lower (by 31.0–57.1% and 47.5–74.4%, respectively). The soil phytolith and PhytOC content decreased significantly with soil depth, especially once the marsh has become moderately degraded. Alpine marsh degradation reduced the accumulation of soil PhytOC by decreasing the PhytOC input flux, thereby altering the long-term carbon sequestration mechanism of phytoliths in this alpine-marsh wetland ecosystem.

Phytolith‐occluded carbon (PhytOC) is an important long‐term stable carbon fraction in grassland ecosystems and plays a promising role in global carbon sequestration. Determination of the PhytOC traits of different plants in major grassland types is crucial for precisely assessing their phytolith carbon sequestration potential. Precipitation is the predominant factor in controlling net primary productivity (NPP) and species composition of the semiarid steppe grasslands. We selected three representative steppe communities of the desert steppe, the dry typical steppe, and the wet typical steppe in Northern Grasslands of China along a precipitation gradient, to investigate their species composition, biomass production, and PhytOC content for quantifying its long‐term carbon sequestration potential. Our results showed that (a) the phytolith and PhytOC contents in plants differed significantly among species, with dominant grass and sedge species having relatively high contents, and the contents are significantly higher in the below‐ than the aboveground parts. (b) The phytolith contents of plant communities were 16.68, 17.94, and 15.85 g/kg in the above‐ and 86.44, 58.73, and 76.94 g/kg in the belowground biomass of the desert steppe, the dry typical steppe, and the wet typical steppe, respectively; and the PhytOC contents were 0.68, 0.48, and 0.59 g/kg in the above‐ and 1.11, 0.72, and 1.02 g/kg in the belowground biomass of the three steppe types. (c) Climatic factors affected phytolith and PhytOC production fluxes of steppe communities mainly through altering plant production, whereas their effects on phytolith and PhytOC contents were relatively small. Our study provides more evidence on the importance of incorporating belowground PhytOC production for estimating phytolith carbon sequestration potential and suggests it crucial to quantify belowground PhytOC production taking into account of plant perenniality and PhytOC deposition over multiple years., PhytOC stores of plants in various grassland steppe types show distinct difference. Climatic factors affected phytolith and PhytOC production of steppe communities mainly through altering plant production. The importance of the PhytOC store in belowground production should be taken into account when estimating PhytOC sequestration potential.

Background The fern Dicranopteris linearis is a hyperaccumulator of rare earth elements (REEs), aluminium (Al) and silicon (Si). However, the physiological mechanisms of tissue-level tolerance of high concentrations of REE and Al, and possible interactions with Si, are currently incompletely known. Methods A particle-induced X-ray emission (μPIXE) microprobe with the Maia detector, scanning electron microscopy with energy-dispersive spectroscopy and chemical speciation modelling were used to decipher the localization and biochemistry of REEs, Al and Si in D. linearis during uptake, translocation and sequestration processes. Results In the roots >80 % of REEs and Al were in apoplastic fractions, among which the REEs were most significantly co-localized with Si and phosphorus (P) in the epidermis. In the xylem sap, REEs were nearly 100 % present as REEH3SiO42+, without significant differences between the REEs, while 24–45 % of Al was present as Al-citrate and only 1.7–16 % Al was present as AlH3SiO42+. In the pinnules, REEs were mainly concentrated in necrotic lesions and in the epidermis, and REEs and Al were possibly co-deposited within phytoliths (SiO2). Different REEs had similar spatial localizations in the epidermis and exodermis of roots, the necrosis, veins and epidermis of pinnae of D. linearis. Conclusions We posit that Si plays a critical role in REE and Al tolerance within the root apoplast, transport within the vascular bundle and sequestration within the blade of D. linearis.

The interpretation of crop water management practices has been central to the archeological debate on agricultural strategies and is crucial where the type of water strategy can provide fundamental explanations for the adoption and use of specific crops. Traces of water administration are difficult to detect and are mostly indirect, in the form of water harvesting or distribution structures. Attempts have been made to infer plant water availability directly from archaeobotanical remains. Current evidence suggests that the ratio of sensitive to fixed phytolith morphotypes can be used as a proxy for water availability in C₃ crops, as well as in sorghum and maize. Nevertheless, the controversy on whether genetically and environmentally controlled mechanisms of biosilica deposition are directly connected to water availability in C₄ crops is open, and several species remain to be tested for their phytolith production in relation to water levels. This research aims at clarifying whether leaf phytolith assemblages and concentration, silica skeleton size and ratio of sensitive to fixed morphotypes can be related to different water regimes in Eleusine coracana Gaertn., Pennisetum glaucum (L.) R. Br., and Sorghum bicolor (L.) Moench. We cultivated 5 traditional landraces for each species in lysimeters, under different watering conditions and analyzed their phytolith content/production in leaves. Results show higher proportions of long cells, bulliforms and stomata produced in well watered conditions. The model built on the basis of phytolith composition has been then applied to interpret archeological phytolith assemblages recovered from a single phase at four different sites of the Indus Civilisation: Harappa, Kanmer, Shikarpur and Alamgirpur. The results show that most probably C4 crops grew under water stress conditions, providing new data on the interpretation of ancient agricultural management in the Indus Valley. We would like to thank all the GEMS team (ICRISAT) who helped during the fieldwork, particularly Rekha Baddam and Suresh Naidu as well as Dr. Krithika Anbazhagan and Dr. Sunita Choudhary whose suggestions have been invaluable and benefited the success of the study. Thanks are due to Alessandra Varalli for her support and guidance and to Carolina Jiménez-Arteaga for the fruitful discussions on millets. This work is part of the RAINDROPS project founded by the European Research Council (ERC-Stg-2017) under the grant agreement 759800. Universitata Pompeu Fabra health and safety measurements have been followed during both the fieldwork and the laboratory work. RAINDROPS has received ethical approval from the Institutional Committee for Ethical Review of Projects (CIREP) at Universitat Pompeu Fabra (ethics certificate n. 2017/7662/I). The work for this paper was carried out when F.D., J.R.P., M.M. and C.L. were members of the CaSEs (UPF), a Research Group of the Catalan Agency for Research (AGAUR SGR 212).

Here we present a continuous palaeoclimatic record of 5980 years (7230 cal BP–1250 cal BP) from Hetapatti, a Neolithic site situated on the western fringe of the Central Ganga Plain. The region was a center of reurbanisation following the decline of the Harappan civilisation and is considered a hub of economic, political and religious evolution since the sixth millennium BC. Hetapatti contains an uninterrupted sequence from Neolithic to Historic (Gupta) period. The study integrates two different approaches (phytoliths and carbon isotope analysis) to infer vegetational and climatic changes and to understand their relationship to the cultural sequence. Our results show a gradual transformation from a warm and humid climate into a warm and dry climate from the Neolithic to Historic (Gupta) period. We find an abrupt weakening of the ISM at ~2080 cal BP driving a warm and dry climate. The comparison of our data with other high resolution regional and global records led us to hypothesise a synchronicity in this warm and dry trend, coeval with the Roman warm period (RWP). The observed variation in vegetation and climate might have driven by the fluctuations in the Indian Summer Monsoon (ISM). Additionally, the phytolith analysis provides evidence of cereal crops including rice, wheat, barley, millets, etc. suggesting a crop affinity with the earlier Indus crop package. It is interesting to note that the site displays an uninterrupted cultural sequence from Neolithic to Historic times, with artefacts of each phase exhibiting technological and stylistic developments from the preceding culture. From this we infer that the well adapted socio-ecological strategies and availability of perennial rivers may have helped the ancient civilisation to absorb the stress relating to a varying climate.

Although phytolith analysis is a promising tool for reconstructing the palaeovegetation in grassland ecosystems, no phytolith study has yet attempted to quantitatively reconstruct the corresponding plant community characteristics. Questions remain regarding whether or not soil phytoliths can quantitatively reflect various aspects of grassland physiognomy, and how well modern phytoliths represent the quantitative characteristics of grassland ecosystems. These are important scientific issues in the field of phytolith analysis, which require further research on the modern phytoliths of grassland ecosystems. In order to explore the potential of phytolith analysis in the temperate grassland region, we have for the first time established a modern soil phytolith reference dataset by exploring the relationships between soil phytoliths and plant species inventory data from 77 sites in the Songnen grassland in Northeast China. The results show that phytolith assemblages can clearly distinguish Leymus chinensis grassland, Stipa grassland and mesophytic herb grassland. In addition, we found that the Ic phytolith index could discriminate samples of L. chinensis grassland from the other samples, while the Iph phytolith index proved to be less reliable in the region. In addition, in terms of quantitative plant community characteristics, the soil phytoliths showed a good correspondence with plant community cover and species richness, but not with biomass and diversity index. The transfer functions established in this study can provide reliable estimates of community cover and species richness in the Songnen grassland. In addition, phytoliths are shown to have the potential to reconstruct the taxonomic abundance of the aboveground plant community. This study is a major advance in the application of phytolith analysis to the quantitative estimation of plant community characteristics, and it provides a modern phytolith reference for the quantitative reconstruction of the paleovegetation of grassland ecosystems.

Phytoliths can be an important source of information related to environmental and climatic change, as well as to ancient plant use by humans, particularly within the disciplines of paleoecology and archaeology. Currently, phytolith identification and categorization is performed manually by researchers, a time-consuming task liable to misclassifications. The automated classification of phytoliths would allow the standardization of identification processes, avoiding possible biases related to the classification capability of researchers. This paper presents a comparative analysis of six classification methods, using digitized microscopic images to examine the efficacy of different quantitative approaches for characterizing phytoliths. A comprehensive experiment performed on images of 429 phytoliths demonstrated that the automatic phytolith classification is a promising area of research that will help researchers to invest time more efficiently and improve their recognition accuracy rate., This work was supported by the project TIN2015- 67534-P (MINECO/FEDER, UE) of the Ministerio de Economía y Competitividad of the Spanish Government, by the project BU085P17 (JCyL/FEDER, UE) of the Junta de Castilla y León (both projects co-financed through European Union FEDER funds) and by Grups de Recerca de Qualitat CaSEs – Culture and Socio-Ecological Dynamics (2017 SGR 212), AGAUR-Generalitat de Catalunya. The authors gratefully acknowledge the support of NVIDIA Corporation and its donation of the TITAN Xp GPUs used in this research.

Phytolith analysis is increasingly being applied in studies of Neotropical forest history and associated pre-Columbian human influences, especially in the Amazon Basin. In order to enlarge modern reference collections that are integral to these efforts, we analyzed phytoliths from 360 species of mainly eudicotyledons from 80 different families and 10 Arecaceae species. Many are native to Amazonia and have not been studied previously. Production and morphological characteristics of the phytoliths were assessed along with their survivability in ancient soils and sediments. Our analysis affirmed the validity of family- and genus-level diagnostic phytoliths from arboreal and other woody growth taxa uncovered in previous research. It also revealed new diagnostic phytoliths from both well- and little-studied families of importance in the Amazonian forest, and affirmed the utility of other types such as spheroids and sclereids for documenting arboreal/woody growth more generally in paleoecological research. Although where pollen is recovered it will continue to document a greater number of arboreal/woody species, phytoliths can identify a diversity of those taxa in the Amazonian and Neotropical forest at large--including when pollen does not-- with family, genus, and possibly even species-level diagnostics.

The uptake and deposition of silicon (Si) as silica phytoliths is common among land plants and is associated with a variety of functions. Among these, herbivore defense has received significant attention, particularly with regard to grasses and grasslands. Grasses are well known for their high silica content, a trait which has important implications ranging from defense to global Si cycling. Here, we test the classic hypothesis that C4 grasses evolved stronger mechanical defenses than C3 grasses through increased phytolith deposition, in response to extensive ungulate herbivory ("C4 -grazer hypothesis"). Despite mixed support, this hypothesis has received broad attention, even outside the realm of plant biology. Because C3 and C4 grasses typically dominate in different climates, with the latter more abundant in hot, dry regions, we also investigated the effects of water availability and temperature on Si deposition. We compiled a large dataset of grasses grown under controlled environmental conditions. Using phylogenetically informed generalized linear mixed models and character evolution models, we evaluated whether photosynthetic pathway or growth condition influenced Si concentration. We found that C4 grasses did not show consistently elevated Si concentrations compared with C3 grasses. High temperature treatments were associated with increased concentration, especially in taxa adapted to warm regions. Although the effect was less pronounced, reduced water treatment also promoted silica deposition, with slightly stronger response in dry habitat species. The evidence presented here rejects the "C4 -grazer hypothesis." Instead, we propose that the tendency for C4 grasses to outcompete C3 species under hot, dry conditions explains previous observations supporting this hypothesis. These findings also suggest a mechanism via which anthropogenic climate change may influence silica deposition in grasses and, by extension, alter the important ecological and geochemical processes it affects.

Phytolith records from three proximal freshwater shell midden sites document plant exploitation and local palaeoecological changes during the early Holocene in present-day Nanning City, Guangxi Province, China. Radiocarbon dating of freshwater gastropod shells indicates the midden sites formed sequentially, with variable chronological overlaps: Baozitou at 12,000-11,130 cal BP, Shichuantou at 11,250-10,500 cal BP and Nabeizui at 11,060-9560 cal BP. Palaeoecological data are inferred to show variable trends of forest reduction or recovery during the formation of each midden, suggesting different intensities of site use and impacts upon the local environment. Significantly, palms (Arecaceae) became more frequent during the middle period of formation at each site, which is interpreted to represent resource intensification and selective exploitation of palms by the communities who created each midden.

Forager focus on wild cereal plants has been documented in the core zone of domestication in southwestern Asia, while evidence for forager use of wild grass grains remains sporadic elsewhere. In this paper, we present starch grain and phytolith analyses of dental calculus from 60 Mesolithic and Early Neolithic individuals from five sites in the Danube Gorges of the central Balkans. This zone was inhabited by likely complex Holocene foragers for several millennia before the appearance of the first farmers ~6200 cal BC. We also analyzed forager ground stone tools (GSTs) for evidence of plant processing. Our results based on the study of dental calculus show that certain species of Poaceae (species of the genus Aegilops) were used since the Early Mesolithic, while GSTs exhibit traces of a developed grass grain processing technology. The adoption of domesticated plants in this region after ~6500 cal BC might have been eased by the existing familiarity with wild cereals., eLife digest Before humans invented agriculture and the first farmers appeared in southwestern Asia, other ancient foragers (also known as hunter-gatherers) in southeastern Europe had already developed a taste for consuming wild plants. There is evidence to suggest that these foragers were intensely gathering wild cereal grains before the arrival of agriculture. However, until now, the only place outside southwestern Asia this has been shown to have occurred is in Greece, and is dated around 20,000 years ago. In the past, researchers proposed that forager societies in the Balkans also consumed wild cereals before transitioning to agriculture. But this has been difficult to prove because plant foods are less likely to preserve than animal bones and teeth, making them harder to detect in prehistoric contexts. To overcome this, Cristiani et al. studied teeth from 60 individuals found in archaeological sites between Serbia and Romania, which are attributed to the Mesolithic and Early Neolithic periods. Food particles extracted from crusty deposits on the teeth (called the dental calculus) were found to contain structures typically found in plants. In addition, Cristiani et al. discovered similar plant food residues on ground stone tools which also contained traces of wear associated with the processing of wild cereals. These findings suggest that foragers in the central Balkans were already consuming certain species of wild cereal grains 11,500 years ago, before agriculture arrived in Europe. It is possible that sharing knowledge about plant resources may have helped introduce domesticated plant species in to this region as early as 6500 BC. This work challenges the deep-rooted idea that the diet of hunter-gatherers during the Palaeolithic and Mesolithic periods primarily consisted of animal proteins. In addition, it highlights the active role the eating habits of foragers might have played in introducing certain domesticated plant species that have become primary staples of our diet today.

Three soil samples collected from the Custis Square house site (04BC), located in Williamsburg, Virginia, were submitted for experimental pollen and phytolith analyses to inform the sampling strategy for Colonial Williamsburg archaeologists. Three different depositional environments were selected for review. Pollen analysis was conducted on all three types of samples, while phytolith analysis contributed to understanding two of the contexts.

1. Temperate grasslands exhibit strong spatial and temporal variation in water regimes. Thus, grassland plants experience potentially stressful water regimes, which may influence their tissue silicon (Si) and nitrogen (N) concentrations. Plant Si and N concentrations play important ecological roles in temperate grasslands, for example, by influencing plant performance and herbivory, yet comparisons of species' responses to a broad range of water regimes, including drought, waterlogging and flooding, are lacking. 2. We conducted a mesocosm experiment with 10 temperate grassland species of two life-forms (grasses and forbs) exposed to four different soil water regimes (drought, a benign control, waterlogged and flooded conditions), and analysed their Si and N concentrations. 3. Grasses showed lower Si concentrations under drought and flooding compared to the benign control and the highest concentrations emerged under waterlogging. Overall, plant Si responses of grasses were more uniform, while in forbs, responses varied both in direction and magnitude across species. For N concentrations, all species and life-forms showed the highest concentrations under drought compared to the benign control, while half of the species exhibited decreasing concentrations under waterlogging and/or flooding. The water regimes, especially waterlogging and flooding, induced changes in species rankings of plant Si and N concentrations, with stronger shifts in forbs than in grasses. 4. Our results indicate that spatial and temporal variation of water regimes may influence plant Si and N concentrations in temperate grassland species. Plant Si responses to water regimes might be highly species-specific in forbs but more similar in grasses, whereas plant N responses are likely to be relatively uniform across species and life-forms. 5. The strong plasticity in plant Si and N concentrations we observed might have pervasive consequences for ecological processes, such as herbivory.

Cropland contamination by toxic trace metal (loid)s (TTMs) has attracted increasing attention due to the serious consequential threat to crop quality and human health. Mitigation of plant TTM stress by silica amendment has been proposed recently. However, the relationship between the siliceous structure of phytoliths and TTMs in plants, and the environmental implications of phytolith-occluded trace metal (loid)s (PhytTMs) remain unclear. This study assessed the accumulation of five metal (loid)s, including lead (Pb), zinc (Zn), cadmium (Cd), copper (Cu) and arsenic (As), in the organic tissues and phytoliths of wheat grown in a mixed-TTM contaminated soil under both lightly and heavily contaminated conditions. The results show that the concentrations of plant TTMs and PhytTMs were significantly (p < 0.05) positively correlated, and higher in heavily contaminated wheats than those in lightly contaminated ones. The bio-enrichment factors between phytoliths and organic tissues were higher for As (1.83), Pb (0.27) and Zn (0.30) than for Cd (0.03) and Cu (0.14), implying that As, Pb and Zn were more readily co-precipitated with silicon (Si) in phytolith structures than Cd and Cu. Network analysis of the relationship between soil and plant elements with PhytTMs showed that severe contamination could impact the homeostasis of elements in plants by altering the translocation of TTMs between soils, plants, and phytoliths. The accumulation of TTMs in phytoliths was affected by the capacity of Si deposition in tissues and chelation of TTMs with silica, which could impact the role of PhytTMs in global biogeochemical TTM cycles. Refereed/Peer-reviewed

Phytoliths can act as efficient carriers of information about palaeovegetation and palaeoclimatic conditions, but the representativeness of soil phytoliths from palaeoecological sediments has not been fully understood. In this study, phytolith assemblages in topsoils and associated plant communities at 55 sites in Northeast China were compared. The results indicate that samples from herbaceous and woody communities could be reliably differentiated by topsoil phytoliths. Notably, different phytolith types exhibit varying degrees of representational bias in terms of the aboveground plant community. Some morphotypes (e.g., bilobate, rondel and lanceolate) over‐represent the richness of the corresponding plant; some morphotypes, including microhair, conical epidermal, silicified stomata and epidermal phytoliths, under‐represent the parent plant abundance; additional morphotypes (e.g., elongate, saddle and trapeziform sinuate) are consistent with the changes of associated plants. Based on the representational bias, we calibrated the percentages of topsoil phytoliths and established a phytolith‐based transfer function for precipitation in Northeast China. A palaeoclimate reconstruction in the Changbai Mountains (in the eastern part of Northeast China) based on the above phytolith‐based transfer function for precipitation shows that the region has gone through continuous climatic changes since the late glacial period: from cold and dry conditions to warm and dry conditions, then to warm and wet conditions, and finally to cool and dry conditions. The phytolith‐based reconstructed climate changes since the late glacial period correspond well to those reconstructed by other records from the same stratigraphic profile, and our phytolith‐based climatic reconstruction also confirms the reliability of abrupt cold climatic shifts at 8.2, 6.8, 5.6, 4.6 and 4.2 ka. In conclusion, our results provide the basis for the reliability of phytoliths for reconstructing climatic changes in the northern temperate region. HIGHLIGHTS: Calibrating soil phytolith assemblages for any quantitative palaeovegetation reconstruction using phytoliths is necessary. Phytolith morphotypes in topsoils may over‐ or under‐represent or agree with the abundance of modern plant taxa. Phytolith‐based climatic reconstruction corresponds well with the abrupt climate changes evident since the Late Glacial period and other proxy records.

Background and aims Silicon (Si) deficiency is a major constraint on rice production. The objective of this study was to evaluate the long-term influence of phytolith-rich straw return and groundwa ...

South China preserves a rich archaeological record elucidating the evolution of early modern humans during the Late Pleistocene. However, few studies on plant utilization were conducted in this region. We used phytolith analysis from Yahuai Cave, Guangxi, to infer human use of plant resources over the past 30000 years. AMS 14C dating was used to constrain the chronological framework. Results indicate that several economically essential species were present throughout the sequence including Urticineae (cf. Ulmus sp.), which appears in the lower layers of the sequence (Marine Isotope Stage 3 through Heinrich 1); bamboo and palm which appear throughout the sequence, and wild rice which appears in a clear archaeological context dating to 16000 years ago. This is the earliest record of wild rice in South China and a prerequisite for rice domestication. The unique stone tool assemblages, which resemble those in north China as opposed to South China, point to the possibility that humans, seeking refuge from the colder north, brought their tool kit with them and utilized familiar northern taxa. Warmer South China would have served as a refuge for human populations escaping the cold, harsh climate in the north with more ameliorate conditions in the south.

The Chaco Region is the third biogeographic and morpho-structural territory of South America after the Amazon and Cerrado savannahs. This region is one of the few areas in the world where the transition from the tropics to temperate zones does not consist of a desert but of semi-arid woodlands and savannahs. The modern biodiversity patterns of the region were severely affected by the climatic and environmental changes that occurred during the Quaternary. Remains of an extinct megamammal Neosclerocalyptus sp. (Upper Pleistocene) and charred fossil woods inside of sedimentary nodules, was recently discovered in Chaco Argentina. The aim of paper is the paleoenvironmental reconstruction of quaternary sedimentation in the western Chaco through the taxonomic identification of charred woods and siliceous microfossils analysis. Twenty-three charcoal fragments related to Anacardiaceae, Apocynaceae, Fabaceae, Rhamnaceae and Malvaceae were identified. The phytolith analysis showed that Poaceae elements were the most abundant compared to the other herbaceous and non-herbaceous elements, along with algae and sponge microfossils. Eco-anatomic features of the charcoals and the microfossil remains suggest that environment and climate conditions existed in the area during the Upper Pleistocene were similar to the current one. Finally, the results reveal the presence of natural wildfires during the Quaternary in the region.

Prospecting for sustainable resources will be feasible to generate silica materials extensively used for various commercial applications. Accumulated amorphous silica, called phytolith, is found in the crop residues removed during the harvesting process. Hence, it will be beneficial to understand the potential for various kinds of crop residues used as silica production resource regarding their global generation, yield of generation, and enhancement using silicon fertilizer. Of the many crop residues discussed in this study, sugarcane leaves are the most useful potential silica source. Various synthesis methods are continuously developed with the expectation to achieve tunable silica particle properties with high processing efficiency. The applications for silica particles derived from crop residues vary depending on their unique characteristics related to textural and morphological properties. Silica materials developed from crop residues present several challenges involving silica depletion in croplands, segregation of valuable components from crop residues, and the high utilization of high energy and chemical reagents. Utilizing industrial wastes containing silica can be promoted as Si fertilizer to heal silica depletion in croplands. An integrated approach can be conducted applying low energy with fewer chemical methods to recover energy, lignocellulosic materials, carbonaceous materials, and siliceous material from crop residues, simultaneously.