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Purpose: A prerequisite for the successful application of phytoliths in paleoenvironmental reconstruction is the correct interpretation of their environmental significance. In this context, key questions include: What magnitude of temperature/precipitation change is required to effect significant changes in surface soil phytolith percentages? When temperature/precipitation increases by a certain amount, what is the corresponding response of the percentages and assemblages of surface soil phytoliths? Additional detailed research is required to answer these questions. Materials and methods: We analyzed the phytoliths in 90 surface soil samples collected along the isohyets corresponding to the mean annual precipitation (MAP) of 400 mm (with the mean annual temperature (MAT) range of 3.24℃) and 600 mm (with the MAT range of 8.29℃) in Northeast China. Our objective was to determine the response of phytoliths to different temperature gradients. Soil phytoliths were extracted and identified using heavy liquid separation and microscope observations. Results: The DA of the phytolith percentages enabled the separation of samples collected along the two isohyets, with a total accuracy of 94.44%. MAT was the principal factor affecting the spatial distribution of phytoliths, with an explanation rate of 46.40%. In the surface soil samples collected along the two isohyets, the percentages of ELONGATE, ACUTE BULBOSUS, and PTERIDOPHYTE-TYPE morphotypes, were significantly negatively correlated with MAT, while the percentages of SQUARE were significantly positively correlated with MAT. However, the relationship between PAPILLATE percentages and MAT varied, showing both positive and negative correlations. A temperature gradient of ~ 3℃ was insufficient to significantly affect the percentages of SADDLE, BULLIFORM FLABELLATE, and BILOBATE. The phytolith index (C/W) can be effectively used to reconstruct the palaeoclimate in Northeast China. An MAP change of 200 mm resulted in significant changes in the percentages of ELONGATE, SADDLE, BULLIFORM FLABELLATE, and TRACHEARY (with the respective rates of 39.57%, 780.77%, 179.00% and 81.25%). However, the percentages of ACUTE BULBOSUS, SQUARE, RONDEL, BILOBATE, CRENATE, PTERIDOPHYTE-TYPE, SILICIFIED STOMATA, and PAPILLATE did not change significantly. Conclusions: Our results contribute to an improved understanding of the response of various phytolith morphotypes to temperature, and they provide a modern process basis for future phytolith-based paleoclimatic reconstruction in this region. [ABSTRACT FROM AUTHOR]

This study investigates the reliability of phytolith assemblage analysis for characterizing subtropical vegetation and explores the potential for using these modern phytolith–vegetation relationships for paleoenvironmental interpretation in southeastern China. The samples were collected from five common subtropical vegetation communities in the Daiyun Mountains, southeastern China, with the above-ground vegetation recorded at each plot. Constrained ordination analysis was used to determine the most important factor governing the variations in phytolith assemblages that could be quantitatively reconstructed with weighted averaging partial least squares regression (WAPLS). The relationship between modern phytolith assemblages and the parent vegetation, as well as production, dispersal, and taphonomic processes, was discussed. Results demonstrated that the main subtropical biomes in southeastern China could be well distinguished by soil phytolith assemblages. In particular, the overall amount of tree coverage was well represented by topsoil phytolith assemblages. Grass silica short cell phytoliths (GSSCP) tended to occur in higher proportions in open habitats (shrub-meadow) at higher elevations, whereas non-grass phytolith morphotypes attained higher frequencies under mixed and broadleaf forests at lower elevations. Human-induced deforestation might increase the frequency of GSSCP within the bulk phytolith assemblage. Our results constitute the primary phytolith reference data for the subtropical zone in southeastern Asia where vegetation change during the Holocene period, particularly forest shifts, anthropogenic deforestation, and early agriculture are poorly documented. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Background and aims: 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. Methods: 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. Results: 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. Conclusion: 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. [ABSTRACT FROM AUTHOR]

Phytoliths are a reliable paleovegetation proxy and have made an important contribution to paleoclimatic studies. However, little is known about the depositional processes affecting soil phytoliths, which limits their use for paleoclimate and paleovegetation reconstructions. Here, we present the results of a study of the vertical translocation characteristics of phytoliths in 40 natural soil profiles in Northeast China. The results show that phytolith concentration decreases within the humic horizon of the soil profiles and that ∼22% of the phytoliths are translocated below the surface of the studied soils. In addition, we find that the translocation rate of phytoliths varies markedly with phytolith type and that phytolith size and aspect ratio also have a significant effect. Phytoliths with length >30 μm and with aspect ratio >2 and those with length <20 μm and aspect ratio <2 are preferentially translocated compared to those with length >25 μm and aspect ratio <2. Our results demonstrate that differential translocation of phytoliths within soil profiles should be considered when using soil phytoliths for paleoclimate and paleovegetation reconstruction. [ABSTRACT FROM AUTHOR]

The assessment and calibration of representational bias in modern soil phytolith assemblages provide the basis for improving interpretation of fossil phytolith assemblages. We studied soil phytolith representation by comparing phytoliths from living plant communities with those from paired surface soils, representing 39 plant communities in Northeast China. Together with the use of representation indices, the 34 and 30 soil morphotypes observed in forest and grassland samples, respectively, were both classified into the following four groups: “Associated types” were similarly represented in soils and in the corresponding species inventory data; “Over-represented types” and “Under-represented types” were respectively over- and under-represented in soils compared to the inventory data; and, in the case of “Special types,” the relationship with the parent plants was unclear. In addition, the diagnostic types exhibited different degrees of representation, while the most common morphotypes were equally represented between grassland samples and forest samples. On this basis, a comparison between the original and corrected soil phytolith indices of the additional 29 soil samples was conducted. The soil phytoliths frequencies corrected by R-values differed between plots with differing plant compositions, and were moderately consistent with actual plant richness in the plot inventory data. We therefore confirmed that R-values are a promising means of correcting soil phytoliths for representational bias in temperate regions. The corrected soil phytoliths can be used to reliably reflect vegetation variability. Overall, our study provides an improved understanding of soil phytolith representation and offers a potential method for improving the accuracy of paleovegetation reconstruction. [ABSTRACT FROM AUTHOR]

To provide a basis for tracing changes in vegetation and tree cover density, we studied the phytoliths of 129 common temperate plant species, and extracted the phytoliths from 75 surface soil samples from sites in grassland, forest−grassland ecotone and forest habitats in northeast China. From the analysis of shapes and morphological parameters of the plant samples, we developed a reference data set of herbaceous and woody phytoliths, and subsequently identified 21 herbaceous and 13 woody phytolith types in the surface soil samples. To test the reliability of soil phytolith analysis for distinguishing forest, grassland and the forest−grassland ecotone, we used principal components analysis (PCA) and discriminant analysis (DA) to summarize the soil phytolith assemblage characteristics of the different ecosystems. The results show that the grassland and forest samples are characterized by abundant herbaceous and woody phytoliths, respectively; and that forest−grassland ecotone habitats are characterized by low abundances of blocky polyhedral, multifaceted epidermal and sclereid phytoliths. In general, the surface soil phytolith assemblages can reliably differentiate samples from forest, grassland and the forest−grassland ecotone, with up to 92% of the samples classified correctly. We also tested the reliability of phytolith indices (W/G (1), W/G (2), W/G (3)) for discriminating different vegetation types in our study area, and found that W/G (2) was the most reliable index and corresponded well with the species inventory data. The W/G values for grassland ranged from 0 to 0.3, from 0.3 to 0.6 for the forest−grassland ecotone, and exceeded 0.6 for forest. We conclude that our study provides reliable analogues for phytolith assemblages from palaeoecological contexts, which can be used to reconstruct shifts in forest−grassland ecotones and vegetation succession in temperate areas. [ABSTRACT FROM AUTHOR]

Based on the widespread distribution and abundant phytoliths produced by Phragmites communis, phytoliths of P. communis in northeast China were investigated to identify the primary influencing factors on phytolith size using an orthogonal experimental method. Temperature and precipitation were found to be the prominent factors influencing the sizes of short-cell phytoliths including the saddle and the rondel morphotypes, whereas there were no obvious variations in the width-to-length ratios of short-cell phytoliths in response to environmental factors. These results indicate that short-cell phytoliths are genetically stable, confirming that they can be used for the classification of grasses. Moreover, precipitation was the main factor influencing the sizes of the lanceolate phytoliths and silicified stomata, and their width-to-length ratios changed significantly in response to precipitation and habitat differences. These findings reveal that lanceolate and silicified stomata phytoliths are sensitive to environmental changes, indicating their usefulness for palaeoenvironment reconstruction. Moreover, variations in their width-to-length ratios and their sizes may provide some information for plant classification, even at species level. Finally, the results of a principal component analysis of the sizes of P. communis phytoliths further verify the reliability of the orthogonal experiment results, in that temperature and precipitation were the prominent factors influencing the size of all P. communis phytoliths except for the length of saddle and width of the saddle morphotypes. This research into the primary environmental significance of the sizes of P. communis phytoliths may contribute to improving the precision of plant classification and the model for quantitative reconstruction of the palaeoenvironment to aid in reconstructions of palaeovegetation and palaeoclimate. [ABSTRACT FROM AUTHOR]

Abstract: Research on response of phytolith assembles in Phragmites communis to two treatments is a new idea for studying global change. As P. communis is an important dominant species in the Songnen Grassland and widely distributed in sampling area and produce abundant phytoliths. P. communis was selected as the material and target to find a link between the phytolith variety and elevated CO2 concentration. An OTC (open top chamber) was used to elevate the concentration of CO2, and the phytoliths in P. communis were investigated to identify the effects. The phytolith record reveals the elevation of CO2 concentration can change the ratio of different types and size of phytoliths significantly. The number of silicified stomata and Saddle decreased while hair cell increased after elevated CO2 treatment. Moreover, after the measurement using a particle-size analyzer and under a microscope, phytoliths grow smaller after elevated CO2 treatment. Research on relationship between phytolith and CO2 concentration renews the traditional understanding. This study introduces a different way to study the influence of global change, and the use of common reed could provide basic data for other studies to make regional contrast with the same species. [Copyright &y& Elsevier]

Modern process research on phytoliths, including on the characteristics and spatial distribution of phytoliths assemblages and their relationship with environmental factors, is the basis of the use of phytoliths in paleoenvironmental reconstruction. We collected 54 surface soil samples along the isohyet of 600 mm in Northeast China in order to determine the relationship between modern phytoliths distributions and temperature. These were comprised by 20 samples from Xiaoxing'an Mountains, 32 samples from Songliao Plain, and 2 samples from Liaoxi Hills. The main phytoliths types were elongate and lanceolate, followed by short cell phytoliths, blocky, tabular and cuneiform; the percentages of the other types were all less than 1% and only occurred sporadically. There were significant differences in phytoliths assemblages among Xiaoxing'an Mountains, Songliao Plain, and Liaoxi Hills. Discriminant analysis was conducted using phytoiths assemblages, the samples from these three regions could be separated with a total accuracy of 96.30%. Elongate, lanceolate and pteridophyte‒type on average made up the largest proportion in Xiaoxing'an Mountains and the smallest in Liaoxi Hills, whereas saddle, bilobate and papillae showed the inverse trend; the proportions of blocky, tabular and cuneiform were the largest in Songliao Plain. The percentages of these types abovementioned were significantly different among the three regions. Correlation analysis revealed a significant negative correlation between the percentages of elongate, lanceolate and pteridophyte‒type and mean annual temperature (MAT), while there was a significant positive correlation between the percentages of blocky, tabular, cuneiform, saddle, bilobate, papillae and MAT. There was no significant relationship between rondel, trapeziform sinuate, conduit, carinate, sclereid, silicified stomata and MAT. A phytoliths index (C/W) based on the common phytoliths types in the surface soil samples which had a significant correlation with MAT was built. C/W = (elongate + lanceolate)/(elongate + lanceolate + blocky + tabular + cuneiform + saddle + bilobate). The values of C/W in Northeast China varied from 0.14 to 0.91, with an average of 0.67. The accuracy of the C/W index indicating climatic trends was significantly higher than the previously established Ic (climate index) and Iw (warm index). Overall, our results contribute to an improved understanding on the environmental significance of various phytoliths morphotypes, and provide a modern process foundation for phytoliths–based paleoclimatic reconstruction in the study region. [ABSTRACT FROM AUTHOR]

• Spatial distribution patterns of surface soil phytoliths under the single factor of precipitation were studied at the regional scale. • This study provides an improved understanding of the response of various phytolith morphotypes to precipitation. • A modern process basis for future phytolith–based paleoclimatic reconstruction in Northeast China is delivered. • An index applicable for reflecting changes in environmental humidity in Northeast China is built. The characteristics of topsoil phytolith assemblages can reflect the local vegetation and climatic conditions. We collected 53 topsoil samples along an isotherm corresponding to a mean annual temperature (MAT) of 4 °C in Northeast China, 20 samples were from the Daxing'an Mountains (DXAM), 18 samples from the Songnen Plain (SNP), and 15 samples from the Changbai Mountains (CBM). The phytoliths were classified into 13 morphological categories. We observed significant differences between the phytoliths assemblages from the DXAM, SNP, and CBM, and they could be statistically discriminated with a total accuracy of 81.1 %. ELONGATE percentages were more sensitive to MAT than to mean annual precipitation (MAP). There was a significant positive correlation between the percentages of ELONGATE, PTERIDOPHYTE-TYPE, PAPILLATE and MAP; and a significant negative correlation between the percentages of BILOBATE and MAP. We constructed a phytolith index (D/W) based on the common phytolith types, which reflects changes in environmental humidity: D/W = BILOBATE / (BILOBATE + ELONGATE); the higher the value of D/W the drier the environment, and vice versa. In Northeast China, D/W varied from 0.0 to 0.6, with the average of 0.3. D/W < 0.3 corresponded to a relatively humid climate, and D/W > 0.3 corresponded to a relatively dry climate. [ABSTRACT FROM AUTHOR]

Many prehistoric cultural sites with distinctive regional characteristics have been discovered on fixed aeolian dunes in Nenjiang River Basin, Northeast China. The rise and decline of these cultures was substantially influenced by the regional environmental evolution. To elucidate how human activity responded to environmental changes, we conducted analyses of phytoliths, grain-size and organic content of a natural sediment profile at Honghe Neolithic site. The phytolith analysis shows that the vegetation was dominated by C3 Pooideae, and the grain-size analysis shows that the site was strongly affected by the winter monsoon and that the sediment source was regionally-derived aeolian sand from Songnen Sandy Land. The environment of Nenjiang River Basin experienced several periods of sand dune mobilization and stabilization: During 7024-4233 cal yr BP, 3414-2433 cal yr BP and 1700-1000 cal yr BP the dunes of Songnen Sandy Land were stable and the environment was warm and wet. During 4233-3,414 cal yr BP, 2433-1,700 cal yr BP and 1000 cal yr BP-present the dunes were mobile and the climate was cold and dry. In addition, the global 4.2 ka cold climatic event is recorded in the section. Correspondingly, the human history can be divided into three periods: (I) Neolithic Age (7024-4, 233 cal yr BP) when the winter monsoon was weak, the sand dunes were stable and the environment was warm and wet. Human activity was relatively intense during this period, manifested by the Angangxi Culture in the middle reaches of Nenjiang River, a representative of the 'Fishing-Hunting Neolithic Culture'. However, only a small number of tombs post-dating 4200 cal yr BP have been found in the Angangxi district (II) Bronze Age (4233-2, 433 cal yr BP). The Xiaolaha Cultural sites in the lower reaches of Nenjiang River, which inherited the characteristics of the Angangxi Culture, flourished during 3800-3260 cal yr BP, and after a transitional period it gradually evolved into the Baijinbao Culture (2800-2,500 cal yr BP). This pattern of evolution shows that human activity diminished in the middle reaches of Nenjiang River after 4233 cal yr BP, in response to the colder and drier environment. (III) Post-Warring States period (2 433 cal yr BP - present). The Hanshu II culture prospered during 2380-2067 cal yr BP, and the Hongmashan Culture was the dominant culture during 2000-1700 cal yr BP. Historical documents and archaeological evidence revealed that frequent wars interrupted the continuity of human cultural development after 2000 cal yr BP in the Nenjiang River Basin. [ABSTRACT FROM AUTHOR]

Research on phytolith morphology and the preservation of phytoliths in soils provides the theoretical basis for reconstructing shifts in forest–grassland ecotones and the evolution of plant communities. Based initially on anatomical origin, then shape and finally texture, phytoliths in broad-leaved trees were divided into six major types, 10 types and 33 sub-types, respectively; and correspondingly phytoliths in coniferous trees were divided into seven major types, 9 types and 20 sub-types. Results of detrended correspondence analysis showed that broad-leaved trees were characterized by epidermal phytoliths, hair, hair base, sclereid, elongate attenuate, stomate and tracheids; while the main coniferous phytoliths were elongate, tabular, blocky and margin-cuneiform. In Pinaceae, Larix closely corresponded to elongate and margin-cuneiform; Picea and Abies to blocky scrobiculate, stomate and tracheids; while Pinus corresponded well with epidermal, blocky and tabular. Only five kinds of broad-leaved phytoliths and seven kinds of coniferous phytoliths appeared in soils. The preservation degree of different phytolith types was determined by comparing the contents of the same phytoliths in plants and soils. Evidence showed that coniferous phytoliths were better preserved than broad-leaved ones. Among coniferous phytoliths, the cubic, tabular echinate and elongate cavate phytoliths were better preserved than other types. Among broad-leaved phytoliths, sclereid and blocky facetate showed the best preservation. Overall, this research will support the more accurate use of tree phytoliths in interpreting paleo-environments and paleo-vegetation. [ABSTRACT FROM AUTHOR]

Phytolith dissolution, during both plant-to-soil transportation and post-depositional processes, may alter phytolith assemblages in soils. This inconsistency may complicate archaeological studies and palaeoenvironment reconstructions based on phytolith assemblages in the strata. In the present study, we extracted phytoliths from surface soils and the overlying vegetation at 13 sites to assess the factors that influence the preservation of phytoliths in soils in natural conditions and to identify those morphotypes likely to be lost or enriched in soil assemblage. The results showed that rectangle, bulliform and oblong morphotypes were enriched in soils, while rondel point, hooklike and cylindric tenuis morphotypes were largely lost. The enrichment or loss is associated with phytolith dimensions — phytoliths of large, thick, and robust appearance were more stable and enriched in soils; phytoliths that were long and narrow forms, or tiny and thin forms, were fragile and easily degraded in the soil. The concentration ratios of different morphotypes varied in different vegetation zones, due to the differences in the environmental factors and plant species. [ABSTRACT FROM AUTHOR]

This study uses new herbaceous phytolith indices to reconstruct the paleoclimate in the Changbai Mountains, NE China. In this study, we collected 52 pairs of herbaceous quadrats and corresponding topsoils: 25 were from the understory (UND) and 7 were from the non-understory (NON) in the Changbai Mountains; whereas the other 20 were from the grassland (GRA) of Songnen Plain for comparing the forest area of the Changbai Mountains. The phytolith analyses of the 104 modern samples provide a guide of using herbaceous phytolith indices as paleoclimate reconstruction. The herbaceous quadrats of the Changbai Mountains contained more long-cell phytoliths and fewer short-cell phytoliths compared to the herbaceous quadrats of the Songnen grassland; and similar situations appeared in the corresponding topsoil phytoliths. The ratio of short cell% to long cell% (S/L) in the topsoil can be used to discriminate grassland (S/L > 1.65) and forest (<1.65), with discriminant accuracy of 80%. Furthermore, in the forest region, S/L in the topsoil is low for the non-understory (NON) (<0.46), and relatively high for the understory (UND) (0.46 < S/L < 1.65), probably due to preservation of short-cell phytoliths. The ratio of rondel% to lanceolate% (Ro/La) reflected the same trend as S/L for the forest region: Ro/La < 0.23 indicating NON, and Ro/La > 0.89 indicating UND. Thus, lower S/L and Ro/La ratios may reflect more development of NON in the forest region under relatively warm conditions, whereas higher S/L and Ro/La values indicate better development of UND with cold climates. These two indices (S/L and Ro/La) from a peat profile in the Changbai Mountains were further used to reconstruct the paleoclimate since 7670 a BP. The phytolith analyses of 33 peat samples from the 326-cm long core showed four ordinal clustering zones: Zone I (7670–4060 a BP) with low mean S/L (0.42) and Ro/La (0.78) was characterized as warm. In Zone II (4060–2580 a BP), S/L and Ro/La fluctuated around mean values of 0.47 and 3.40, respectively; indicating cooler climate than Zone I. Zone III (2580–640 a BP) was characterized by the highest mean values of S/L (0.53) and Ro/La (6.97) in the profile, reflecting the coldest condition in the record. In Zone IV (640 a BP–modern), the average values of S/L and Ro/La were 0.31 and 1.14, respectively. Both indices increased initially and then declined, perhaps reflecting the colder climate of the Little Ice Age, followed by a warming period. The climatic patterns of the Changbai Mountains reconstructed from the herbaceous phytolith indices agreed with the Ic index and pollen analysis from the same peat profile, suggesting that these new herbaceous phytolith indices should be applicable in paleoclimate reconstruction. [ABSTRACT FROM AUTHOR]

Phytoliths have proved to be reliable indicators of environmental conditions both at present and in the past, and can provide evidence for the distribution of taxa or vegetation. Understanding the environmental significance of phytoliths within plants helps in drawing more reliable inferences about palaeovegetation and in reconstructing the palaeo-environment. The present study examined the relationship between phytoliths and environmental factors to assess the environmental significance of different types of phytoliths. Phytoliths were extracted from Phragmites communis growing in xerophytic and aquatic habitats at twelve sampling sites in north-eastern China and their implications for the environment were assessed using quantitative data mainly including phytolith concentration and environmental factors and statistical analyses. Principal component analysis (PCA) of several environmental factors (including the climate, micro terrain, and the physicochemical properties of soils) revealed that other factors being constant, P. communis phytolith concentrations were influenced largely by the average annual temperature and precipitation. Orthogonal experiment analysis and three-way analyses of variance of the concentrations confirmed the reliability of the results of the PCA. More specifically, the concentrations of the saddle and rondel types of phytoliths (the short-cell phytoliths) were closely linked to the average annual temperature whereas those of the elongate, lanceolate, and bulliform phytoliths (the non-short-cell phytoliths) were more sensitive to the variations in water status. The results contribute to further confirming the major environmental implications of phytoliths and, in turn, providing a reference for growth and development of wetland plants. Our findings also provide critical information that could help managers and policymakers assess and modify ecological restoration practices. [ABSTRACT FROM AUTHOR]

Accuracy of paleovegetation reconstruction and understanding of phytolith formation would both be improved by further study of phytolith size in the Phragmites australis under different environmental conditions. Leaves of P. australis were collected from 11 sampling sites in northeast China with differences in temperature, precipitation and habitat. Principal component analysis of environmental factors (climatic and edaphic) indicated that the annual averages of temperature and precipitation were the main factors influencing phytolith size. Moreover, three-way analyses of variance (ANOVAs) further showed that phytolith size differed significantly under conditions of different temperature or precipitation gradients, whereas habitat differences had little effect. The changes in phytolith size with temperature differed in the humid, semi-humid and semi-arid areas of northeast China. In the humid and semi-humid areas, moving from the temperate to the warm temperate zone, increasing temperature reduced phytolith size; whereas in the semi-arid area, phytolith became larger with increasing temperature. In the warm temperate and temperate zones, the changes of phytolith size with precipitation showed the same trend—moving from the semi-arid to semi-humid to humid areas, as precipitation increased, phytolith grew larger. Finally, ANOVA revealed that phytoliths were also sensitive to habitat. These findings demonstrated that the size of P . australis phytoliths was sensitive to environmental factors: for regional research, the annual averages of temperature and precipitation were the major factors influencing size, but in the same climate district, habitat differences seemed to also have a significant impact on phytolith size. Consequently, phytolith analysis has potential utility in the study of global climate change, palaeoenvironment reconstruction, and environmental conservation and restoration. [ABSTRACT FROM AUTHOR]

Phytoliths as a climate proxy are one of the most important and effective tools for reconstruction of paleoenvironment. In this paper, twelve Gramineae species of the subfamilies Panicoideae, Pooideae and Arundinoideae from the Changbai Mountains were selected, and 3698 phytoliths were counted. We measured six parameters of dumbell, elongate, lanceolate, crenate, saddle and silicified stomata. The seven shape factors of different types of phytoliths were deduced by the six parameters measured above and analyzed by nonparametric testing and discriminant analysis. The nonparametric testing indicated that the average value of the shape factor SF 4 among the three subfamilies was obviously different. Discriminant analysis for the three subfamilies, also revealed that the discriminant accuracy was high (89.81%). Total discriminant accuracy using shape factors of dumbell phytoliths of Panicoideae was 73.12%. Discriminant accuracies using shape factors of elongate, lanceolate and crenate phytoliths of Pooideae were respectively 60.87, 59.21 and 87.07%. The discriminant accuracies using shape factors of saddle phytoliths and silicified stomata of Arundinoideae were 59.06 and 71.77%. At the same time, the shape factors of phytoliths from Setaria viridis and Leymus chinensis were used to test whether the discriminant functions established at the subfamily level were effective or not. Results showed discriminant functions precisely classify them, thus verified discriminant functions were useful. In conclusion, using the seven shape factors of phytoliths not only may improve the accuracy of classifying Gramineae, but also provides basis reference data for better understanding the presence and function of Gramineae plants at archaeological sites. [ABSTRACT FROM AUTHOR]

Abstract: Leaves of Phragmites communis were collected from five sampling sites distributed across three climatic zones in NE China, each zone representing a different level of humidity. A total of 4372 phytolith particles were counted from the leaves and classified into six types. The types of phytoliths are saddle, lanceolate, bulliform, and rondels, elongated, favose. Phytoliths in P. communis are sensitive to change in humidity. The main types from the five sampling sites are identical. The proportion of saddle phytoliths is greater than other phytoliths types. However, the quantity of phytoliths in P. communis differs markedly across the five sampling sites. In Shalan, Changchun, and Changling, the corresponding proportions of the saddle type are 28.1%, 25.4%, and 37.6%. In samples representing the aquatic, seasonal waterlogged, and mesic sampling sites from Nanhu Lake in Changchun, the corresponding proportions for saddle phytoliths are 32.6%, 20.6%, and 23.0%. The size of phytoliths, tested by CA, VA and PCA, to some extent indicates that the humidity is the main factor affecting the phytoliths. In Shalan, Changchun, and Changling, as humidity decreases, the phytoliths grow larger. In Nanhu Lake, as humidity decreases, the phytoliths grow smaller. The result reveals that phytoliths in P. communis are both sensitive to temperature and humidity. For regional research, temperature is the most important factor in the formation of phytoliths. Lanceolate phytoliths are sensitive to habitat change, and the saddle phytoliths are also sensitive to regional differences. Compared with the long cell phytoliths, short cell phytoliths as a proxy indicator of paleoclimate are more convincing. Overall, the results confirm that humidity is one of the dominant variables controlling the formation of phytoliths, which provides a new thinking for palaeoenvironmental reconstruction. [Copyright &y& Elsevier]

Understanding local-scale paleoecological processes and their driving mechanisms is a major challenge in plant community ecology. However, phytolith records have the potential to retrieve localized signals of the evolution and patterns of past ecosystems. As a case study, we selected a forested region in Northeast China. We first established a modern phytolith reference dataset which enabled numerical estimates to be made of various aspects of the plant community. We then apply the dataset to a phytolith record from a sedimentary profile (HN) from the Changbai mountain region in order to quantitatively reconstruct the evolution of the vegetation since the last deglaciation. The results of partial least squares regression were used demonstrate that modern phytoliths can quantitatively estimate plant community coverage, species diversity and dry weight ratio; three numerical estimates respectively explained 62.3%, 50.3% and 49.5% of the variance. These quantitative relationships can provide reliable modern phytolith analogues for paleoecological reconstructions. The modern phytolith-based vegetation reconstruction indicates that the Changbai mountain region was dominated by forest communities since the late glacial period. The temporal development of the vegetation can be summarized as follows: boreal or coniferous forest, sparse and species-poor → mixed broadleaf-conifer forest, relatively dense and species-rich → mixed broadleaf-conifer forest, dense and species-rich. The phytolith-inferred changes in plant community coverage, dry weight ratio and species diversity correspond well with climatic changes. This supports the view that the environmental background mainly dominates ecosystem evolution, and it also confirms the utility of phytolith records to resolve local paleovegetation patterns and evolution. [ABSTRACT FROM AUTHOR]

• There is a correspondence between phytolith morphotypes from topsoil and communities. • ~31% of phytoliths are transported from the soil profile in the forested region. • ~19% of phytoliths are transported from the soil profile in the grassland region. • R and T values are a promising approach for revising soil phytolith preservation. The reliability of soil phytoliths within representatives of past phytolith assemblages in archaeological and palaeoecological contexts needs to be improved. In this study, we investigated soil phytolith representation by comparing phytoliths from plant communities with those from paired topsoils and those subjected to vertical translocation at 54 sites in Northeast China. With respect to soil phytolith preservation in the soil-plant system, there is a reasonable correspondence between phytolith morphotypes from forested topsoil (or grassland topsoil) and those from the associated communities. But the comparison and contrast between phytoliths from topsoil and communities indicates that different phytolith morphotypes also exhibit different degrees of representational bias (R values). Additionally, for the vertical translocation of soil phytoliths, together with a phytolith translocation index (T), ~31% and 19% of the phytoliths are transported below the surface of the studied soil profiles in the forested and grassland regions, respectively. The translocation rates of different phytolith morphotypes in the forested samples are all larger than those in the grassland samples. Based on R and T values, the changes of revised topsoil phytolith indices are moderately in accord with actual plant richness and climatic changes. These results we show that the R and T values are effective parameters indicating the degree of soil phytolith preservation and can be used in future studies for developing training sets of modern phytolith assemblages. The results of our study provide a methodological template to investigate the extent to which phytolith assemblages in palaeoenvironmental contexts satisfy the criteria necessary to justify their use as a meaningful proxy of past ecological and climatic change. [ABSTRACT FROM AUTHOR]