中文摘要：

在松嫩草原应用红外线增温和人工施氮的方法对羊草群落模拟全球变暖和氮沉降,提取羊草中的植硅体,分析探讨植硅体的形态及数量变化规律.羊草中的植硅体可以划分为4个大类和12个亚类,以及较小的植硅体碎片,其中帽型植硅体含量高达70%.尖顶帽型和平顶帽型植硅体与刺帽型植硅体可能有不同的发育机制,并且尖型植硅体对施氮更为敏感;与对照相比,增温处理对羊草植硅体的发育有促进作用（长宽增加0.1～2.6μm）,而施氮处理则有一定的抑制作用（长宽减小0.1～1.4μm）,增温和施氮交叉作用,则施氮对羊草植硅体发育表现出的抑制作用明显减弱;施氮处理中出现其他处理中未见到的空心棒型（占棒型总量的46%）,而且除棒型、帽型、尖型以外的植硅体含量增加到10%,从而推测,对于以羊草为优势植物的松嫩草原,施氮的影响可能要强于增温,如果两者同时作用,增温能在一定程度上缓解施氮的影响.实验中的羊草植硅体对模拟全球变化很敏感,说明植硅体对环境因子的改变很敏感,其作为古环境的代用指标应是可靠的.

英文摘要：

Using infrared radiator and applying nitrogen on Leymus chinensis community on Songnen grassland to simulate global warming and nitrogen deposition,phytolith was extracted from L.chinensis,the morphology and content of phytolith were analyzed.Phytolith in L.chinensis were classified into 4 main classes and 12 subclasses,as well as some small phytolith fragments.Of all the phytolith types,the hat-shaped take as much as 70%.The hat-shaped with spire and hat-shaped with flat peak may have different growth mechanisms from the echinate hat-shaped,and the point-shaped phytolith is more sensitive to N deposition.Compared with control check（CK）,the warming treatment seemed to promote the growth of phytolith（increased the length and width 0.1-2.6 μm）,while the N deposition treatment had an effect of inhibition on the growth of phytolith（decreased the length and width 0.1-1.4 μm）,and when warming and N deposition mixed,in this treatment the effect of inhibition caused by N deposition declined.Hollow elongate（46% of elongate） was observed only in N deposition treatment,and the content of other types（elongate,point-shaped,hat-shaped excluded） increased to 10%,it was supposed,as L.chinensis is the dominant species in Songnen grassland,the effect of N deposition might be more significant than warming on such grassland,and warming could mitigate the affection of N deposition.Phytolith was sensitive to the change of environmental factors,this study provided an experimental evidence for phytolith as a reliable proxy indicator for paleoenvironment.