Effects Of Nitrogen Deposition And Mixed Acid Rain Stress On Photosynthetic And Water Physiology Characteristics Of Typical Subtropical Trees

As humans industrialized production, the use of chemical fertilizers increased, theincreasing of the amount of private cars, as well as the decrease of the production of sulfuremissions, made the ecological system in the nitrogen cycle of change, the amount ofnitrogen deposition, mixed acid rain increase, to the land productivity of plant ecosystemsand influence the structure and function., therefore, this article selects the typicalsubtropical area of three plants Cinnamomum camphora, Schima superba, Cyclobalanopsisglauca seedlings as the research object, through the determination of plant seedlings indifferent amount of nitrogen deposition process, growth under different mixed acid raintreatment, the relative contents of chlorophyll and photosynthesis, water physiologicalchanges in different seasons, the analysis of nitrogen deposition and mixed acid rain effecton three kinds of plants, and for the increase of nitrogen deposition, acid rain pollutiontypes by sulphuric acid type to sulphuric acid, nitric acid mixed shift the impact of theecological systems of land plants in China to provide a certain basis. Experimental set upfour nitrogen deposition process: control (CK:0g·m^-2·yr^-1), low nitrogen (LN:6g·m^-2·yr^-1),medium nitrogen (MN:12g·m^-2·yr^-1), high nitrogen (HN:24g·m^-2·yr^-1); Three mixed acidrain treatment: pH2.5, pH4.0, pH5.6（CK）. Come to the conclusion that the several aspects:1. Cyclobalanopsis glauca along with the increase of nitrogen deposition is topromote growth after the value of the first inhibition, high nitrogen have inhibitory effecton Cinnamomum camphora base diameter, nitrogen deposition of Schima superba growtheffect was not significant.2. PH2.5hybrid of Cyclobalanopsis glauca growth inhibition effect of acid rain, andthe promoting effect of Schima superba a, pH4.0mixed acid rain to promote the growth ofCinnamomum camphor.3. The influence of nitrogen deposition on plant chlorophyll relative content related tothe season, summer high nitrogen restrain Schima superba a chlorophyll relative content,low nitrogen spring inhibition of Schima superba chlorophyll relative content;Spring/summer promotion of Cyclobalanopsis glauca s chlorophyll relative content; Thespring and autumn period and the promoting effect to the Cinnamomum camphorchlorophyll relative content of nitrogen.4) With mixed acid pH promote chlorophyll relative content of Cyclobalanopsisglauca fall fall, spring and summer promote chlorophyll relative content of Cinnamomumcamphor pH2.5promote chlorophyll relative content of Schima superba mixed acid rain. 5. Spring low nitrogen increase three plants dark respiration rate （R_d）, nitrogendeposition autumn reduce the apparent quantum efficiency of three plants （AQE）, nitrogenin autumn improve Cyclobalanopsis glauca, Schima superba, light saturation point （LSP）and light compensation point （LCP）, spring and summer of nitrogen increase maximum netphotosynthetic rate (A_max) camphor.6. Along with the mixed in the decline of pH value of acid rain in the spring ofCyclobalanopsis glauca s R_d, AQE, A_maxrising, rising and Schima superba a R_d,LSP andthe decrease of the LCP, R_d, AQE, Cinnamomum camphor in the fall of the A_maxrise, LCP.7. Nitrogen in the spring, high nitrogen promote Cyclobalanopsis glauca, schimasuperba, net photosynthetic rate （Pn）, stomatal conductance （Gs）, intercellular CO₂concentration （Ci）, high nitrogen restrain Cinnamomum camphor net photosynthetic rate,stomatal conductance, intercellular CO₂concentration, transpiration rate （Tr）, low nitrogenpromotes three plants instantaneous water use efficiency （WUEt）, nitrogen deposition ofthree plants WUEi effect was not significant.8. PH2.5mixed acid rain in the spring of camphor, Cyclobalanopsis glauca Pn haspromoting effect, and inhibit the Pn of Schima superba, Gs, Ci, Tr values, WUEi andWUEt raised three plants; Autumn promoted the Pn camphor, Gs, Ci, Tr, WUEi values, butalso improve the Cyclobalanopsis glauca WUEi and WUEt.