To investigate the physiological and ecological strategies of light adaptation in subtropical broadleaved tree species, the modified rectangular hyperbola model and the FvCB model were used to fit the fluorescence CO
2 response curves (
A/
Ci curves) of
Sapium sebiferum,
Cyclobalanopsis glauca, and
Castanopsis sclerophylla under different light intensities (200, 500, 800, and 1100 μmol·m
-2·s
-1). The photosynthetic physiological and biochemical characteristics of these species were then analyzed. The results showed that when intercellular CO
2 concentration (
Ci)<30 Pa, leaf net photosynthetic rate (
A) of the three tree species increased almost linearly, and the greater the light intensities, the greater the increase of
A. When
Ci>30 Pa, the increase of
A tended to be slow. Under the same
Ci,
A increased significantly with the increase of light intensity. Stomatal conductance (
gs) decreased with the increase of
Ci. Under the same
Ci,
gs increased significantly with the increases of light intensity. When
Ci<35 Pa, the electron transport rate (
J) of PSII increased significantly with the increases of
Ci. When
Ci>35 Pa,
J tended to be stable with the increases of
Ci. Under the three light intensities (500, 800 and 1100 μmol·m
-2·s
-1), initial carboxylation efficiency (
Φc) was significantly greater than that at light intensity of 200 μmol·m
-2·s
-1. When light intensity >500 μmol·m
-2·s
-1, leaf photosynthetic capacity (
Pnmax) of the three species were higher than that at lower light intensities. Mesophyll conductance (
gm) increased significantly with the increases of light intensity. The maximum electron transfer rate (
Jmax), maximum carboxylation rate of Rubisco (
Vcmax), and light dark respiration rate (
Rd) were not affected by light intensity.
Sapium sebiferum,
Cyclobalanopsis glauca, and
Castanopsis sclerophylla could enhance photosynthetic carbon sequestration capacity by increasing
gm and light energy utilization efficiency under high light intensities, and the photosynthetic physiological and biochemical characteristics responded significantly to light intensity changes, which provide an important theoretical basis for the breeding of subtropical plantation tree species and the prediction of forest carbon sink dynamics under the background of global climate change.