Studies On Dynamics Of Carbon Absorption And The Influencing Factor Of Phyllostachys Pubescens In Yue Hill Of Lin'an

Research of terrestrial ecosystems carbon absorption ability is one of the hot topics about global climate change. Forests of Phyllostachys pubescens is one of the main vegetation types in the subtropical area of China. The preliminary study of P. pubescens obtained that this kind of bamboo not only can achieve great economic benefits, but also has strong carbon-sink function, because of peculiarly growth feature and manual management pattern. It will make the quantity of carbon assimilate maximization, that the further research of dynamics of carbon absorption under intensive management, and proper reform and innovation of traditional production operation habit according to that dynamic of carbon absorb principle.In this paper, a 15m tall observation tower was built in the P. pubescens forest under intensive farming on Yue hill in Lin'an, Zhejiang Province, China. A LI-6400 Photosynthesis analyzer system was used to measure the curves of Pn-PAR of leaves of 1,3,5-year-old P. pubescens in experimental filed. The values of Pmax calculating with the data above, expressed seasonal dynamic variation. A SPAD-502 chlorophyll meter also was used to measure monthly chlorophyll relative content. In autumn, a relatively stable climate season, the curves of Pn-PAR and Pn-Ci, determined under different conditions, such as doubled CO₂ concentration, different grades of humidity and temperature, simulate the photosynthetic rate change when CO₂ concentration heighten, global warming came. Finally, the data was analyzed using SPSS13.0 and Excel.The research showed that: 1. The Non-rectangular hyperbolic model and light response curve of P. pubescens were fitting best, while the exponential model was calculating the most accurately value of LSP and LCP. 2. Carbon absorption capacity of P. pubescens leaf existed obvious seasonal difference. There are two fastigiums of carbon absorption in one year: May, Jun. and Oct., Nov. and two troughs: at high temperature period of Jul. Aug. in summer and low temperature period, leaf change stage in spring and winter. 3. At fastigium, carbon sequestration capacity of P. pubescens in 5 significantly higher than the bamboo in 3and 1; but there is no significant difference of carbon sequestration ability among different ages of bamboo in the low period. 4. The main ecological factor influence of bamboo carbon assimilate ability were PAR, Tl and RH. The physiological factors higher relatedness with Pn were Gs, Ci, Tr, WUE and Ls. 5. With the CO₂ concentration short-term growth, the net photosynthetic of the bamboo rate to accelerated. The temperature short-term increase or decrease made Pn always diminution. Atmosphere dry increased Gs and Pn, but the change range of Pn was far less than transpiration rate.Cutting and hooking tips of forestry of P. pubescens usually were carried out in Sep. to Nov.. Bamboo is in peak of carbon sequestration in Sep. to Nov., therefore, delaying hooking and cutting can increase carbon sequestration of bamboo. Therefore, it is suggested that the hooking should be carried out in Dec. before snow, and cutting should be carried out in Dec. to Mar.. Although rise of CO₂ concentration was better to increase the photosynthetic rate of bamboo, the high temperature caused moisture loss. To P. pubescens lived in moist conditions in subtropical, there was no adaptability of regulation mechanism to drought. So, increases of CO₂ concentration may be adverse effects, at least not so significantly higher estimated once, to the photosynthesis of P. pubescens, even all plant lived in subtropical areas.The main innovation of this paper was using Pmax as index seasonal variation. This method reduced the error which was caused by instantaneous changes of light intensity, made carbon sequestration ability can be reflected better. Additionally, the study of the short-term response of P. pubescens to temperature and atmosphere humidity let the further research considering global change not just stay on the influence of CO₂ concentration.