Ecophysiological Responses Of Schima Superba To Nitrogen And Water Deposition

Global environmental change,such as regional drought and nitrogen depssition,has becoming more serious and urgent than ever before.Forest vegetation is faCing unprecedented pressure to survive,and the environmental factors interaction influence on forest,forest vegetation physiological ecology measures how to adapt to changing environment,which has become hot issues ecologists research.This study selected the subtropical evergreen broad-leaved edificators:S.superb.nitrogen and water deposition the growth interaction pattern(plant height,basal diameter,crown breadth),chlorophyll content and chlorophyll fluorescence characteristic,gas exchange characteristics,biomass and its distribution pattern,blade stable carbon isotope and S.superba leaf CNP in the influence of physiological ecology characteristics.This study from morphology(plant height,basal diameter,crown breadth,biomass and distribution pattern,chlorophyll content,etc.),photosynthetic physiology(chlorophyll fluorescence characteristics of gas exchange characteristics)and ecological chemical remember learning characteristics(S.superba root leaf distribution and the concentration of CNP)three aspects of S.superba onnitrogen and water deposition response mechanism of interaction that will help to understand and predict the impact of climate change on forest vegetation,for further research on nitrogen deposition and the influence of the interaction of plant water stress to provide basic data.Under isolation rain shelter,NH4NO3 as plus nitrogen source,setting interaction simulatednitrogen and water deposition experiment,to design the four levels of nitrogen deposition:design control CK(0kgNhm-2·a-1),low nitrogen LN(50kg Nhm-2·a-1),medium nitrogen(100kg Nhm-2·a-1),high nitrogen HN(150kg Nhm-2·a-1),and each nitrogen deposition sample set three water stress uniform again,according to the soil moisture content of the percentage of the field capaCity design:no water stress(W1,100%),mild water stress(W2,60%),severe water stress(W3,30%),and interact with the experiment.Results show that:(1)among the various groups of Schima superba height,breadth of interaction between nitrogen and water are significantly different.Water stress increased inhibits the growth of S.superba;In low nitrogen treatment promote the growth of S.superba,high nitrogen treatment and produce inhibition for thegrowth of S.superba.(2)among the treatment groups of leaf,stem,root and lateral root biomass of interaction between nitrogen and water are significantly different.Water stress decreased the total biomass of S.superba,increased the root weight ratio and root cap ratio of S.superba,reduces the leaf weight ratio and stem weight ratio.Promote the growth of the total biomass,nitrogen deposition in low and high nitrogen deposition reduce total biomass nitrogen water(3)among the various groups.of Schima superba leaves Pn,Trm,Gs and Ci nitrogen water interactions have significant differences.Water stress of S.superba photosynthesis,nitrogen deposition in the lower promote high photosynthesis and nitrogen deposition inhibition.(4)among the various groups of Schima superba leaves ETR,Yield,Fv/Fm,Fo,NPQ,D nitrogen water interactions have significant differences.Exacerbate S.superba suffered from light water stress,from the point of nitrogen deposition process,low nitrogen deposition can reduce plant suffered from suffering photoinhibition,high nitrogen deposition and make S.superba photoinhibition phenomenon.In the high and low water stress,nitrogen deposition NPQ value and heat dissipation D were higher.Leaf blade dissipation of excess light energy into heat,in order to protect the photosynthetic mechanism from harm,reach the purpose of protection of light,this is one of the adaptation mechanism of nitrogen water under the interaction of S.superba.(5)Treatments of carbon nitrogen,phosphorus,nitrogen in leaves and stems are significantly different,but phosphorus content in the root differences between treatment groups is not significant.Water stress inhibits the absorption of S.superba carbon and nitrogen content,promote the absorption of phosphorus.The absorption of nitrogen deposition promotion of S.superba carbon and nitrogen content,inhibit the absorption of phosphorus.Trade-off theory,in the absence of water stress,the contrast and S.superba growth under low nitrogen deposition is mainly restricted by nitrogen,and settlement of high nitrogen phosphorus restrictions.In high water stress,under control and high nitrogen deposition growth of S.superba restricted by nitrogen deposition,and low nitrogen and nitrogen under heavy processing by the phosphorus.(6)Treatment of S.superba leaf ?13C values are significantly different.Nitrogen deposition and moderate levels of water stress interaction was significantly higher than the other.Results from most index,nitrogen deposition has influence to water stress,the two factors are not independent.Low nitrogen deposition mitigating the effects of water stress on plant;with high nitrogen deposition is aggravating the influence of water stress on plant.The nitrogen deposition and moisture of the present study the influence of two factors of S.superba does not support "Independent action theory".In the low nitrogen deposition to reduce the negative effects of water stress(Promote theory),aggravating the negative effects of water stress and high nitrogen deposition(Balance theory).And the tolerance ability has been had by Schima superba to water stress and nitrogen deposition.