Spatial And Temporal Difference Among Phytoliths Of Phragmites Australis In Northeast China

In the paper, Phragmites australis are collected in twelve sample sites which are chosenin Northeast China according to the difference of temperature and humidity. We mainly studythe change rules of their phytolith morphotypes during different growing stages and differentcombinations of temperature and humidity. And this is significant for improving accuracy ofreconstructing paleo-vegetation, identifing the environmental implication of phytoliths andprobing into the formation mechanism of phytoliths.In this paper, the phytoliths of the leaves of Phragmites australis which are collectedfrom the twelve sample sites in Northeast China are analyzed. And we get five results in thispaper as follows.Firstly, the result shows that the main phytolith morphotypes of Phragmites australiscould be classified into5categories: saddle, rondel, bulliform (including square), lanceolate,elongate. There is a little change about phytolith assemblages in Phragmites australis duringdifferent growth periods and different combinations of temperature and humidity. This impliesthat phytolith morphotypes of the same plant species are stable, which can effectivelyreconstruct paleo-vegetation. And under different combinations of temperature and humidity,there is some difference on the percentage and the concentration of phytoliths while time goes.This explains that the change of quantity of phytoliths could reflect the variation ofenvironment under certain circumstances.Secondly, it is found that the maximum value of the saddle percentage appears in July,then a slight decrease. It reflects that the formation of the saddle may be more controlled inplant photosynthesis and transpiration. Furthermore, the maximum value of the concentrationof the saddle in Phragmites australis appears in August, with its minimum value in September.In Northeast China, with the change of the latitude, the concentration of the saddle becomesrelatively large at the sample sites which are from Dandong to Harbin. In the sample siteswhich are from Mudanjiang to Nehe, the concentrations of the saddle decrease quickly inSeptember and October.Thirdly, the maximum value of percentage and concentration of the bulliform appears inAugust or September, with its minimum value in July. This result reflects that the formation ofthe bulliform may be closely associated with the support of bulliform cells for plants.InNortheast China, the concentration of the bulliform is comparatively small, but with thechange of the latitude, the bulliform have a larger concentration in the sample sites with lowerlatitude, while the concentration of the bulliform is small in the sample sites with higherlatitude. Fourthly, the result also shows that the concentration of the phytoliths in Phragmitesaustralis don’t gradually accumulate while time goes, so it infers that the change rules ofphytoliths concentration may be concordant with the needs of the silicon in different growthperiods of plants. In Northeast China, the concentration of the phytoliths in Phragmitesaustralis become relatively large in the sample sites with lower latitude, but there is smallconcentration of the phytoliths in Phragmites australis and the phytoliths in Phragmitesaustralis in the sample sites with higher latitude. But the relationship between the variation ofthe phytoliths in Phragmites australis and the atitude is not obviously linear.Fifthly, by the research of the coefficient of variation of the phytolishs, the extent ofvariation of the concentration of the phytoliths in Phragmites australis and the saddle inPhragmites australis turns small from June to October with higher latitude in the east and thecentral part of Northeast China, while it turns large from June to October with lower latitudein the west of Northeast China. The extent of variation of the concentration of the bulliform inPhragmites australis turns small from June to October with higher latitude in the east, thecentral part and west of Northeast China. From June to October, the extent of variation of theconcentration of the saddle and the phytolishs in Phragmites australis of the12sample sitesis large in September and October, while it is small in the other three months. From June toOctober, the extent of variation of the concentration of the bulliform in Phragmites australisis large in July, while it is small in the other four months.