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Effects Of Simulated Nitrogen Deposition On Greenhouse Gas Emissions And Plant Diversity In Tumen Wetland

Posted on:2020-01-21Degree:MasterType:Thesis
Country:ChinaCandidate:X J ZhangFull Text:PDF
GTID:2370330596970265Subject:Ecology
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Increased nitrogen deposition has become one of the important phenomena of global change,which can potentially affect greenhouse gas emissions from soil and plant diversity on the surface,leading to changes in ecosystem functions.Therefore,it is very important to study the change of vegetation diversity and the negative feedback of greenhouse gases under the condition of atmospheric nitrogen deposition for predicting future atmospheric CO2 and other greenhouse gases content through terrestrial carbon and nitrogen cycle,as well as for predicting the interaction between the atmosphere and biosphere.At the same time,it is helpful to understand the nutrient cycle and water cycle of the earth's ecosystem.Gradual changes in ring and biodiversity.In this paper,the wetlands in the lower reaches of Tumen River,a typical lowland wetland area,were studied.The fluxes of three greenhouse gases?CO2,CH4,N2O?from the end of May to the end of September were observed by static chamber/meteorological chromatography.The effects of different nitrogen deposition on the fluxes of greenhouse gases in wetlands were revealed,and the seasonal variations of three Greenhouse Gases Fluxes and the abundance of communities were clarified.The trend of carbon sink in the lower reaches of Tumen River and its response to the increase of nitrogen deposition were analyzed.The results show that:?1?With the increase of nitrogen deposition,soil pH value and available phosphorus content gradually decreased,SOC,TN,nitrate nitrogen,ammonium nitrogen and TP content increased with the increase of nitrogen deposition.There were significant differences among soil TN,nitrate nitrogen,ammonium nitrogen and available phosphorus?F=6.82,P<0.05?.There were no significant differences among soil pH,SOC and TP?F=1.31,P>0.05?.?2?Shannon-Wiener index?Shannon-Wiener index?of Tumen wetland plants increased with the change of nitrogen deposition.Compared with the control group,low and high nitrogen treatments were significantly higher than the control group.In natural control plots,the average Shannon-Wiener index was 4.76,in low nitrogen application plots,the Shannon-Wiener index was 5.38?+1.09?,and in high nitrogen application plots,the Shannon-Wiener index was 5.76?+1.32?.The results of variance analysis showed that the Shannon-Wiener index of Tumen wetland increased with the increase of nitrogen?F=16.41,P<0.05?.?3?Compared with the control,the plant dominance index showed that the low nitrogen treatment was significantly higher than the control treatment,but the high nitrogen treatment was not significantly higher than the control treatment,and the effects of low nitrogen and high nitrogen on the vegetation community dominance were different.The plant evenness index increased with the change of nitrogen deposition.Compared with the control,the low nitrogen and high nitrogen treatments were significantly higher than the control.?4?Under different nitrogen deposition gradients,the greenhouse gas emission fluxes of Tumen Wetland showed significant differences among three nitrogen deposition treatments?ONE-WAY ANOVA F=12.37,P<0.05?.Nitrogen deposition increased CO2 emission fluxes?F=8.25,P<0.05?.The CO2 emission rate varied with seasons,with the highest in summer and the lowest in autumn.?5?There was no significant difference in CH4 emission flux among three nitrogen deposition treatments?ONE-WAY ANOVA,F=6.48,p>0.05?.Nitrogen deposition did not promote CH4 emission flux,and CH4 emission rate was higher in summer and autumn.?6?N2O emission flux was significantly different among three nitrogen deposition treatments?ONE-WAY ANOVA,F=6.82,P<0.05?,and nitrogen deposition increased N2O emission flux?F=5.48,P<0.05?.N2O emission rate is the highest in summer and autumn.?7?Pearson correlation analysis showed that there was no correlation between the three greenhouse gases and diversity index and biomass?p>0.05?;the three greenhouse gases were mainly affected by soil physical and chemical factors,and soil temperature was the main factor affecting soi l CO2?R=0.89?and CH4?R=0.83?.
Keywords/Search Tags:Tumen River wetland, Nitrogen deposition, Community diversity, Greenhouse gases, Global climate change
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