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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]

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: 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]