[Response of photosynthesis traits of dominant plant species to different light regimes in the secondary forest in the area of Qiandao Lake, Zhejiang, China].

To understand the mechanisms driving community succession in the secondary forest surrounding Qiandao Lake, Zhejiang, China, we investigated seasonal dynamics of the diurnal variations of net photosynthetic rates, their responses to both light and CO2, and chlorophyll fluorescence parameters of four dominant plant species, i. e., Pinus massoniana, Castanopsis sclerophylla, Lithocarpus glaber and Cyclobalanopsis glauca in three natural light habitats, i. e., gap, edge and understory. In the three different light regimes, the daily mean values of the net photosynthetic rate (Pn) of P. massoniana and C. sclerophylla were significantly higher in summer than in the other seasons, while Pn of L. glaber and C. glauca was significantly higher in autumn than in the other seasons. In the forest gap and edge habitats, the annual mean values of the maximum net photosynthetic rate (Amax), the light saturation point (LSP), light compensation point (LCP) and dark respiration rate (Rd) of P. massoniana were the highest, followed by C. sclerophylla, and those of L. glaber and C. glauca were the lowest. In the understory habitat, the annual mean values of Amax and the apparent quantum yield (AQY) of C. glauca were the highest, followed by L. glaber and C. sclerophylla, and those of P. massoniana were the lowest. The annual mean values of the maximum rate of carboxylation (Vc max), maximum rate of electron transport (Jmax) and triose phosphate use rate (TPU) of P. massoniana were significantly higher than those of the other three plant species in the three different light regimes. During the four seasons, the photochemical maximum efficiency of PSII (Fv/Fm) of P. massoniana and C. sclerophylla in the forest gap habitat was significantly higher, while those of L. glaber and C. glauca in the understory habitat were significantly higher than in the other light regimes. The maximum values of Fv/Fm of P. massoniana and C. sclerophylla were the highest in summer, and those of L. glaber and C. glauca were the highest in autumn. It suggested that P. massoniana and C. sclerophylla were more suitable for habitats with high light intensities such as forest gaps, and L. glaber and C. glauca were more suitable for habitats with low light intensities such as the understory. During ecological succession, P. massoniana and C. sclerophylla would withdraw from the community with the increasing canopy density, and L. glaber and C. glauca would be the dominant species in the climax community.