Photosynthetic Characteristics And Carbon Sequestration Capacity Of Several Commonly Used Tree Species Of Magnoliaceae Of Zhejiang Province

We selected four magnoliaceae tree species commonly used in plains greening frommagnolia garden in Zhejiang agriculture and Forestry University as our targets in thisresearch. The photosynthetic physiological and ecology index and leaf area index weremeasured to evaluate/determine the light response curve, diurnal change characteristics ofnet photosynthetic rate and its influencing factors of tree species. Meanwhile, we alsostudied the carbon sequestration capacity of leaf and single plant of the four species byquantitative methods. The results will provide a scientific basis for selecting high-carbonsequestration species in the plains region afforestation. The main results were as follows:(1) The curves of diurnal variation of net photosynthetic rate indicated that the fourspecies expressed strong ability of photosynthesis in the morning, where the accumulationof carbon was a litter higher. The curves of July and October we obtained all displayed abimodal curve and a obvious midday depression. The causes of midday depression ofphotosynthesis is supposed to be related partly to the stomatal limitation.The correlationanalysis between main physiological and ecological factors and the net photosynthetic raterevealed that transpiration rate, stomatal conductance exhibited very significant positivecorrelation with net photosynthetic rate (P<0.01), and photosynthetic active radiationshowed a significant positive correlation(P<0.05).(2) Leaf area index of the same species in July was all higher than that of October.While, leaf area index of Magnolia denudata decreased greatly during two monthscompared with other three species. In addition, comparing with the other species, Leaf areaindex of Magnolia grandiflora of the two months both reached maximum value, whileMichelia maudiae kept the minimum one. Differences in leaf area index of the four treespecies were pretty significantly, where the differences between Michelia maudiae andboth other three species in July were striking (P<0.05), nevertheless, it was only Magnoliagrandiflora left that had significant differences with Michelia maudiae in October(P<0.05).(3) Carbon sequestration capacity of tree species can not be determined by only one season because their photosynthesis capacity varies from one season to another. Inthis study, carbon sequestration capacity of the specific species was assessed by meanvalue of diurnal net carbon sequestration of two months. Results showed that diurnal netcarbon sequestration of unit area of leaf differed with the four tree species, and the orderwas Magnolia denudata>Michelia chapensis>Magnolia grandiflora>Michelia maudiae;The sequence of diurnal net carbon sequestration of unit crown projection area wasMagnolia denudata>Magnolia grandiflora>Michelia chapensis>Michelia maudiae;Diurnal net carbon sequestration in single plant exhibited Michelia chapensis>Magnoliadenudata>Magnolia grandiflora>Michelia maudiae.(4) The light response curve and simulated physiological characteristics indicators ofthese tree species can reflect their growth adaptability in test area. Results shown thatMichelia maudiae was between negative and positive plant,While the other tree speciesMichelia chapensis, Magnolia denudata and Magnolia grandiflora were typical positiveplants. The difference between light saturation point and light compensation point ofMichelia chapensis reached a maximum. As a consequence, it can adapt to a wide range oflight and have better growth adaptability.Based on the above results, Michelia chapensis and Magnolia denudata had betterecological adaptability and higher carbon sequestration ability. So they are excellentgreening tree species.