不同形态和水平氮添加对三江平原湿地植物群落多样性和生产力的影响OA

Wetland ecosystems are sensitive to global change,and the dramatic increase in atmospheric nitrogen(N)deposition and alterations in nitrogen form pose a serious threat to wetland ecosystems.In this study,we explored the effects of N form and application rate on the structure,diversity and productiv-ity of wetland plant communities in the Sanjiang Plain using one-way ANOVA and Duncan's multiple comparison.We aimed to provide a theoretical basis for understanding the mechanisms of change in wet-land plant community structure and function within the context of global change.The study was carried out on an experimental platform of field N addition in the Sanjiang Plain at the Heilongjiang Academy of Sciences,and three forms of N(ammonium,nitrate and amide)at four levels(0,4,8,and 12 g/m2·a)were set.The addition of ammonium and nitrate nitrogen significantly increased the importance value of the grass functional group(P＜0.05),while the addition of amide nitrogen(urea)significantly increased the importance of weeds.The effects of N application rate on plant community diversity followed a consistent pattern.As the N application rate increased,the Simpson index(species dominance)of the plant commu-nity significantly increased,while the Shannon-wiener(species diversity)and Pielou index(species even-ness)significantly decreased(P＜0.05).However,the interactive effect between nitrogen form and appli-cation rate had no significant impact on species diversity within the plant community.N form,N applica-tion rate,and their interaction significantly affected(P＜0.05)plant community productivity in the wet-lands of the Sanjiang Plain.This was especially true for the application of ammonium and nitrate nitro-gen at a rate of 8 g/m2/a,which significantly increased above ground plant productivity.In conclusion,different functional groups of wetland plants on Sanjiang Plain prefer different forms of nitrogen.The weed functional group prefers amide nitrogen,while the grass functional group prefers ammonium and nitrate nitrogen.The interaction between the form and application rate of N has a significant effect on aboveground productivity of the wetland plant community,whereas species diversity is significantly affected only by the rate of N application.These findings provide a theoretical basis for coping with the dynamic changes of wetland plant communities under various nitrogen deposition scenarios.