Photosynthetic Characteristics of Six Arbor Species in Beijing Mountainous Area

By using Li-6400 portable photosynthesis system,the diurnal changes of the photosynthetic rate of main arbor species were measured in mountainous area of Beijing City in June to September 2006,including Robinina pseudoscacia,Ailanthus altissima,Q.Dentata,Quercus variabilis,Platycladus orientalis,Pinus tabulaeformis.The results showed that net photosynthetic rate in the leaves of Quercus variabilis,Robinia pseudoacacia,Ailanthus altissima appeared in curvilinear changes with double peaks.And apparent strong light intensity,high temperature and low air humidity were the key influencing factors.The stomatal conductance was positively related to net photosynthetic rate closely,and they kept the same change trend.But the intercellular CO2 concentrations of these three species had different change trends.The results also showed that net photosynthetic rate in the leaves of Q.dentate,Pinus tabulaeformis,Platycladus orientalis appeared in curvilinear changes with one peaks.