The Effects Of Nitrogen Deposition And Radiative Forcing On The Photosynthesis And Chlorophyll Fluorescence Characteristics Of Cinnamomum Camphora And Cyclobalanopsis

In recent years, with the development of human activities and the extensive using of fossilfuels and fertilizer as well as development of animal husbandry emit a large number of nitrogencompounds, artificial aerosol emissions had accelerated quickly, radiation forcing has had a hugeimpact on subtropical forest ecological system, all of them had become important in global changeof ecology, nitrogen deposition and radiation forcing were causing more and more seriousenvironmental stresses such as affecting the normal growth of plants. Nitrogen deposition changedN cycle of ecosystem. Radiative forcing and the light factor had changed the subtropical forestecological environment. All of them influence the structure and function of ecosystem. Therefore,through the studying of nitrogen deposition and radiative forcing effects on the subtropical typicalplant species, we can learn more about the subtropical forest adaptation mechanisms to nitrogendeposition and radiative forcing, and the update, succession and recovery of the subtropical foresttropical hardwoods.In this study, the subtropical typical tree seedlings Cinnamomum camphora andCyclobalanopsis glauca were selected for experimental objects, using the method of artificialsimulation nitrogen deposition and composite of radiative forcing environmental conditions, In aneffort to understand the impacts of different nitrogen deposition (high nitrogen, low nitrogen,blank), different radiative forcing (strong radiative forcing, weak radiative forcing, blank) as wellas the two common function on Cinnamomum camphora and Cyclobalanopsis glauca.To studythe two plant seedlings photosynthesis physiological changes, chlorophyll relative contents andChlorophyll fluorescence under the three conditions. We can learn more about the ecologicalcharacteristics of the subtropical forest. The results showed that:(1) Nitrogen deposition and radiative forcing had obvious effects on the photosynthesis of the twokinds of plant seedlings. The photosynthetic rates of the two kinds plant are that nitrogentreatment are greater than the blank, and the low nitrogen treatment is the greatest in nitrogentreatment alone. The photosynthetic rates of the two kinds plant are CK> weak radiativeforcing> strong radiative forcing in radiative forcing treatment alone. The photosynthetic ratesof the two kind plants are the low nitrogen treatment is the greatest, with the increasing ofradiative forcing, the photosynthetic rate decrease, and radiative forcing play leading role in the composite of nitrogen deposition and radiation force effect.(2) For the two subtropical tree species of different species, the change of gas exchangeparameters is different with the change of photosynthesis. Gs is that nitrogen treatment aregreater than the blank, with the increasing of radiative forcing that Gs decrease, and radiativeforcing play leading role. The Ci of Cinnamomum camphora is that nitrogen treatment aregreater than the blank, Cyclobalanopsis glauca is the minimum in the high nitrogen, twokinds of plant seedlings with the increasing of radiative forcing that Ci decrease, nitrogendeposition play leading role. The Tr of two kinds plant are minimum in the high nitrogen, withthe increasing of radiative forcing that Tr decrease, nitrogen deposition play leading role.(3) Nitrogen deposition and radiative forcing had obvious effects on the relative chlorophyllcontent of the two kinds of plant seedling; they are increased with the increasing of nitrogendeposition on the relative chlorophyll content in nitrogen treatment alone. And they areincreased with the increasing of radiative forcing. Nitrogen deposition play leading role.(4) Nitrogen deposition and radiative forcing had obvious effects on the Chlorophyll fluorescenceof the two kinds of plant seedling. Fv/Fm and Fv/Fo are decreased with the increasing ofnitrogen deposition, and Fv/Fm and Fv/Fo are increased with the increasing of radiativeforcing. The two kinds of plant seedling have obvious effects in the two common functions.