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Middle Cretaceous pCO_2 Variation in Yumen, Gansu Province and its Response to the Climate Events 被引量:5
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作者 LEI Xiangtong DU Zhen +2 位作者 DU Baoxia ZHANG Mingzhen SUN Bainian 《Acta Geologica Sinica(English Edition)》 CAS CSCD 2018年第2期801-813,共13页
The palaeo-atmospheric CO2 concentration (pCOz) variation in the Yumen, Gansu Province during the middle Cretaceous has been reconstructed using the newly established plant photosynthetic gas exchange mechanistic mo... The palaeo-atmospheric CO2 concentration (pCOz) variation in the Yumen, Gansu Province during the middle Cretaceous has been reconstructed using the newly established plant photosynthetic gas exchange mechanistic model, and the results show that the pCO2 values are in the range of about 550 -808 ppmv. The present pCO2 values are higher than the pCO2 results (531-641 ppmv) of the previous study according to the Recent standardization of the stomatal ratio method, and much lower than the pCO2 results (882-1060 ppmv) according to the Carboniferous standardization of the stomatal ratio method. The present pCOz variation is not only within the error range of GEOCARB II and GEOCARB Ill but also is similar to the reconstructed results based on the biochemistry and carbon isotope models. Besides, the present Brachyphyllum specimens were collected from four consecutive horizons of the upper Zhonggou Formation of the Hanxia Section, and the reconstructed pCO2 exhibits the reconstructed pCO2 exhibits a decline trend during the late Aptian to early Albian. This decline variation is probably associated with the Oceanic Anoxic Events (OAElb) and the Cold snap event. With the combination of pCO2 during the Albian to Cenomanian recovered by the plant photosynthetic gas exchange mechanistic model, the pCO2 showed a prominent increase during the late Aptian to early Cenominian, which indicates a response to the greenhouse warming during the middle Cretaceous. Therefore, the mechanical model of the plant photosynthetic gas exchange shows a relatively strong accuracy in the reconstruction of thepCO2 and can reflect a strong relation between the atmospheric CO2 concentrations and climatic events. 展开更多
关键词 PCO2 greenhouse climate plant photosynthetic gas exchange mechanical model OAElb Cold snap
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Quantifying key model parameters for wheat leaf gas exchange under different environmental conditions 被引量:2
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作者 ZHAO Fu-nian ZHOU Shuang-xi +3 位作者 WANG Run-yuan ZHANG Kai WANG He-ling YU Qiang 《Journal of Integrative Agriculture》 SCIE CAS CSCD 2020年第9期2188-2205,共18页
The maximum carboxylation rate of Rubisco(Vcmax)and maximum rate of electron transport(Jmax)for the biochemical photosynthetic model,and the slope(m)of the Ball-Berry stomatal conductance model influence gas exchange ... The maximum carboxylation rate of Rubisco(Vcmax)and maximum rate of electron transport(Jmax)for the biochemical photosynthetic model,and the slope(m)of the Ball-Berry stomatal conductance model influence gas exchange estimates between plants and the atmosphere.However,there is limited data on the variation of these three parameters for annual crops under different environmental conditions.Gas exchange measurements of light and CO2 response curves on leaves of winter wheat and spring wheat were conducted during the wheat growing season under different environmental conditions.There were no significant differences for Vcmax,Jmax or m between the two wheat types.The seasonal variation of Vcmax,Jmax and m for spring wheat was not pronounced,except a rapid decrease for Vcmax and Jmax at the end of growing season.Vcmax and Jmax show no significant changes during soil drying until light saturated stomatal conductance(gssat)was smaller than 0.15 mol m^–2 s^–1.Meanwhile,there was a significant difference in m during two different water supply conditions separated by gssat at 0.15 mol m^–2 s^–1.Furthermore,the misestimation of Vcmax and Jmax had great impacts on the net photosynthesis rate simulation,whereas,the underestimation of m resulted in underestimated stomatal conductance and transpiration rate and an overestimation of water use efficiency.Our work demonstrates that the impact of severe environmental conditions and specific growing stages on the variation of key model parameters should be taken into account for simulating gas exchange between plants and the atmosphere.Meanwhile,modification of m and Vcmax(and Jmax)successively based on water stress severity might be adopted to simulate gas exchange between plants and the atmosphere under drought. 展开更多
关键词 biochemical photosynthetic model stomatal conductance model maximum carboxylation rate of Rubisco maximum rate of electron transport drought
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