东北地区芦苇植硅体的变化特征

深入研究芦苇(Phragmites australis)不同生长期植硅体的形态变化规律, 对提高古植被重建精度、探讨植硅体形成机理具有重要意义。该文对东北地区12个样点的芦苇叶片进行研究, 选取长势相近、叶片大小一致的芦苇叶片, 用湿式灰化法提取植硅体并对其进行分类和命名。研究发现, 芦苇植硅体主要有5种类型, 在不同生长期内和不同温湿度组合下, 其植硅体类型组合基本无变化, 说明同种植物的植硅体类型组合具有稳定性, 据此可以有效地恢复古植被; 同时芦苇鞍型植硅体百分含量的峰值出现在7月份, 随后稍有减少, 而芦苇扇型植硅体百分含量和浓度的峰值出现在8或9月份, 谷值在7月份。由此推测芦苇鞍型植硅体的形成可能更多地受控于植物的光合作用和蒸腾作用, 芦苇扇型植硅体的形成可能与机动细胞的支撑作用关系密切。实验结果还表明芦苇植硅体浓度并不是随着时间逐渐积累的, 其在8月份达到峰值, 9月份达到谷值, 因此推测植物植硅体浓度的变化规律可能与植物在不同生长期其自身对硅的需求规律相一致。鞍型植硅体浓度的峰值也出现在8月份, 谷值也在9月份, 其浓度变化与芦苇植硅体总浓度的变化趋势相似。

Change characters of Phragmites australis phytolith in Northeast China

Aims Our objective is to study the change rules of the main phytolith morphotypes in Phragmites australis from June to October.
Methods We selected similarly sized leaves of P. australis in 12 sampling sites and extracted phytoliths with the wet-ashing method.
Important findings The main phytolith morphotypes in P. australis could be classified into five categories. There is little change about the phytolith assemblages in P. australis during different growth periods and different combination of temperature and humidity. This implies that phytolith morphotypes of the same plant species are stable and therefore can be used to effectively reconstruct paleo-vegetation. The maximum value of the saddle percentage appears in July and then slightly decreases. While the maximum value of the percentage and concentration of the bulliform appears in August or September, with its minimum value in July. This indicates that the saddle formation may be more controlled by plant photosynthesis and transpiration, while the bulliform formation may be closely associated with the support of bulliform cells. The result also shows that the phytolith concentration in P. australis does not gradually accumulate from June to October. Its maximum value appears in August and its minimum value in September, so the change rules of the phytolith concentration may be concordant with the need of silicon for plants in different growth periods. Furthermore, the maximum value of the saddle concentration in P. australis also appears in August, with its minimum value in September. This trend is similar to changes of the phytolith concentration in P. australis.