Abstract: The responses of photosynthetic rate(PN)and stomatal conductance(g)of plants at closed,medium closed and open sites and hillslopes to light intensity,CO₂ concentration and leaf/air water vapor pressure gradient are studied.The results show that Psychotria rubra and Rhodomyrl,,s tomenlosa have higher values of PN and g and a higher yield of photosynthetic photon,more adaptive to the environment with higher light intensity.A higher concentration of atmospheric CO₂is of advantage to the increase of PN,and that of Psychotria rltlwn and Rhodomyrtus tomentosa in particular.When Ci is 150pl·L^-1,the PN of Anlaranthus or,tentus is maximum.A higher Ci is available to the maintenance of higher leaf conductance.An increasing leaf/air water vapor pressure gradient can induce the decreasing PN for Ardisia quinquegona and Psychotria rubra, but not for Rhodomprttts tomentosa,which is adapted to arid environment.In disturbed forestland, the pioneer species with higher PN is introduced to improve site condition.

Key words: Disturbed forestland, Plant Photosynthetic rate, Light intensity, CO₂ concentration, Leaf/air water vapor pressure gradient, spatial variability, Huang-Huai-Hai Plain, sequestration rate., soil organic carbon