The Response Of Functional Traits Of Bolboschoenus Planiculmis And Scirpus Nipponicus To Environmental Factors

The response mechanism of plant functional traits to environmental factors has been an important topic in the field of ecology.Plant functional traits difference and adjustment in response to environmental factors reflect different adapting strategies to habitats.Under the background of global climate change,land use change and human activities,the growth and development of wetland plants had been affected with the salinizationand the hydrological processes change of inland saline-alkali wetland.In recently years,the exogenous nitrogen input was increasing in Momoge wetland ecosystem with plenty of agricultural water from surrounding paddy field flow into the wetland,which leads serious threat to the structure and function of the wetland ecosystem.Aiming at understanding the effects of different salinity and nitrogen,water levels and nitrogen,and salt-alkaline stress on plant functional traits of Bolboschoenus planiculmis and Scirpus nipponicus seedling,we conducted three common garden experiments.Through these experiments,we investigated the ecological adaptation strategies of these two species to different environmental factors.The results can provide theoretical and technical support for Momoge wetland management,salt-alkaline wetlands restoration and protection and the protection of food and habitat of Siberian cranes.The main results showed as follows:(1)Salinity has a significant effect on the growth,biomass accumulation,root biomass allocation and leaf biomass allocation of B.planiculmis(p<0.05).With the increase of salinity,the root biomass,sexual reproduction biomass and root-shoot ratio decreased,the specific leaf area(SLA)and the aboveground(stem and leaf)biomass allocation increased.With salinity increased,the height,rhizome biomass,tuber biomass,stem biomass,leaf biomass,underground biomass,aboveground biomass and total biomass all increased firstly and then decreased,the values of these traits were highest at 25 mM salinity compared with other salinity treatments.Appropriate salinity treatment can promote the growth and biomass accumulation of B.planiculmis,but excessive salinity will inhibit the growth and development of this species.At low nitrogen(0 and 50 mgN/kg)and medium nitrogen(100 mgN/kg)addition treatments,the curve of biomass allocation of tuber was U-shaped with the increase of salinity,but the curve of the biomass allocation of root and rhizomes were inverted U-shaped.At high nitrogen(200 and 400 mgN/kg)addition treatments,the results were opposite.Appropriate nitrogen addition reduces the salt stress damage to plants and is conducive to plant growth and development.The biomass of tuber and the total biomass showed a constant growth relationship.The sexual reproduction biomass and total biomass showed a 3/4 power exponential growth relationship.(2)Water level has a significant effect on the growth,biomass accumulation and biomass allocation of S.nipponicus seedling(p<0.05).With water level increasing,individual plant height and aboveground biomass allocation increased,but tiller and tuber number,underground biomass allocation decreased,the biomass of rhizome,tuber,underground,aboveground parts and total biomass all increased first and then decreased.The effects of nitrogen addition treatments on the plant height,tuber number,aboveground and underground biomass allocation were all significant(p<0.05),but not for tiller number and biomass accumulation(p>0.05).We found the optimum water level for the growth of S.nipponicus seedling is 35 cm.Low water level has a positive effect on the absorption and utilization of nitrogen by plants.Both highest water level and highest nitrogen concentration have a negative effect on the growth of S.nipponicus seedling.(3)Salt-alkaline stress has a significant effect on the growth,biomass accumulation and biomass allocation of S.nipponicus seedling(p<0.05).With salt-alkaline stress increasing,individual plant height,tiller number,tuber number,the biomass of root,rhizome,tuber,underground,aboveground parts and total biomass all increased first and then decreased compared with control.The optimum salinity concentration and pH is 25 mM and 7.79(±0.06),respectively.At the highest concentration salt-alkaline treatment(salinity and pH: 200 mM and 10.40(±0.01),respectively),the S.nipponicus seedling can't survive.The effects of salt-alkaline stress on the root,rhizome,tuber biomass allocation and aboveground biomass allocation were all significant(p<0.05).With salt-alkaline stress increasing,root and aboveground biomass allocation increased,tuber biomass allocation decreased.The rhizome biomass allocation of S.nipponicus decreased at 25 mM salinity treatments,but increased at other salinity treatments.Alkali stress is more harmful to the seedlings than salt stress.The alkalization of soil is more detrimental to the growth of S.nipponicus.