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Studying the responses of phytoliths to warming is a new approach to interpret how grassland ecosystems respond to global change. We used an infrared radiator to simulate warming on Phragmites communis in the Songnen Grassland, China - three warming treatments and a control were used to study the relationships between phytolith size and temperature. Warming changed the size of different types of phytoliths. During June-October, the average size of saddle phytoliths decreased and that of hair cell phytoliths and silicified stomata increased with warming. The responses of phytolith size to warming differed among months. With warming, the size of saddle phytoliths, hair cell phytoliths and silicified stomata increased in July and September, but decreased in October. Overall, the results demonstrate that P. communis phytoliths were sensitive to warming. This study provides experimental evidence for phytoliths as reliable proxy indicators for reconstruction of paleo-environments. [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]