东北地区土壤有效硅的时空分异及其对芦苇植硅体形成的影响

TEMPORAL AND SPATIAL VARIATION OF AVAILABLE SOIL SILICON AND ITS INFLUENCE ON THE FORMATION OF PHYTOLITHS IN PHRAGMITES COMMUNIS IN NORTHEAST CHINA

在东北地区按温湿差异选取12个芦苇样点,对其芦苇植硅体、芦苇中有效硅和土壤有效硅进行研究,分析土壤有效硅对植硅体形成的影响,对于植硅体形成机理和古环境重建具有重要意义.结果表明,土壤有效硅含量和植硅体浓度在样点间存在明显差异.在芦苇的不同生长期,土壤有效硅含量差异不明显,芦苇中有效硅含量差异明显.7、8月时,植株吸收的有效硅主要用于植硅体的形成,植硅体浓度较高,且易受到土壤与芦苇有效硅含量比值的影响.9、10月植硅体浓度较低,可能由于成熟期芦苇叶片中硅含量较少而形成较少植硅体.土壤和芦苇有效硅含量的比值约为4时,硅吸收方式可能从主动逐渐转变为被动.此外,芦苇中多数形态的植硅体浓度和土壤与芦苇有效硅含量的比值呈负相关,说明土壤有效硅含量的变化对芦苇植硅体的形成有着一定影响.

This study focuses on the influence of available soil silicon on the formation of phytoliths, which has important implications for the formation mechanism of phytoliths and reconstruction of paleoenvironment. Phytoliths in leaves of Phragmites communis （P. communis） , available silicon in soils and in P. communis from twelve sampling sites are studied in the Northeast （NE） China in 2011. The twelve sampling sites are selected along four section lines from north to south, whitch are located in semi-arid region, semi-humid region and humid region. From June to October, five P. communis samples and three relications of soil samples are collected from within each sampling sites every month. The results show that available soil silicon content and phytolith concentration in P. communis all vary across the sampling sites. The differences of available soil silicon content are small among different growing stages, while the differences of available silicon content in P. communis are the great. In July and August, silicon absorbed by plants is mainly used for forming phytoliths, result in a high phytolith concentration. Phytolith concentration is strongly influenced by the ratio of available silicon. Phytolith concentration is low in September and October. It is likely caused by the low silicon content in the leaves of P. communis at mature stage. We believe that silicon uptake of P. communis will gradually change from active uptake to passive uptake when the ratio of available silicon is about 4. The result of our redundancy analysis show that most phytolith morphotypes in P. communis are negatively correlated with the ratio of available silicon. It suggests that available soil silicon content influence on the formation of phytolith.