Response Of Glyceria Spiculosa Community To Warming And Nitrogen Addition In The Xingkai Lake Wetland

In this paper, the typical Glyceria spiculosa community was chosen to study the effects of warming and nitrogen addition on plant growth strategy and biomass appartion in situ in the Xingkai Hu Nature Reserve, we manipulated a set number of mesocom to copy the global warming by simple open-top chamber and agricultural diffuse pollution by anthropogenic nitrgeon addition. We monitored and analysed the dynamic response of plant growth strategy and biomass apportion in ordet to detect the community stability and succesion tendency. The main results were presented as following:(I)Warming and nitrogen addition have significant influece upon the growth strategy in Glyceria spiculosa community.1. Warming can significantly improve the community density and specific leaf area, which lead a increase in net primary production of Glyceria spiculosa community. So is the effect of nitrogen addition but not so effective.2. Plant height and stem width are the important parameter to calculate net primary production. Both of warming and nitrogen addition can accelerate the growth of plants and biomass accumulation by promoting plant height and stem width.3. Warming had show no effect on leaf index(LI) but significantly decreaing the specific leaf area(SLA), N additon can siganificantly boost up both LI and SLA.4. Warming also can promote photosynthetic rate(Pn) and the content of chlorophyll meanwihle reduce the watre use effcience(WUE). N addtion also enhance the Pn and WUE but show no effects on the content of chlorophyll.(II) Warming and nitrogen addition have significant influece upon the biomass apportion in Glyceria spiculosa community.1. In gernel, Aboveground NPP increased as the temperature increases, compared with the control treatment, increasd by 12.67% and 17.89% respectively. So is the effect of nitrogen additon on belowdground NPP.2. Nitrogen addition also significantly boost the plant growth and Aboveground NPP accumulation. In contrast with control treatment, low nitrogen addtion increased aboveground NPP by 12.14%, but high nitrogen addtion increased aboveground NPP by 40.51%. On the contrary, nitrogen addition showed no effect on blewground NPP.In summary, both warming and nitrogen addition can promote plant growth and reproduction and thus benefit to Glyceria spiculosa community’ s healthy succession. According to the theory of optimal growth under resource constraints, plant growth strategies and biomass allocation modified themselves to suvive or florish under current condition.