Abstract: Castanopsis fargesii, an evergreen broad-leaved tree species, is one of thedominant species in subtropical evergreen broad-leaved forests. This paper presented a comparative study on the photosynthetic parameters, leaf mass per unit area (LMA), leaf nitrogen content, and leaf anatomical structure of C. fargesii seedlings in an evergreen broad-leaved forest under three natural light environments (understory, gap, and open). In understory habitat, C. fargesii  had lower light compensation point (LCP), dark respiration rate (R_d) and LMA, and higher apparent quantum yield (AQY) and photosynthetic nitrogen use efficiency (PNUE), suggesting that this tree species could take advantage of low light and performed high maximum photosynthetic rate (P_max). Moreover, the leaf spongy tissue of C. fargesii  was well developed, and leaf epidermal cells were thicker, demonstr ating a positive response to cooler environment. In open habitat, C. fargesii  had a marked decrease of P_max while an obvious increase of  R_d. Its leaf nitrogen content per unit area (N_a) was higher but PNUE waslower, leaf and palisade tissue became thicker, palisade tissue/spongy tissue ratioincreased, but palisade tissue was lesser developed than spongy tissue, indicating the low adaptability to high light environment. In gap habitat, C. fargesii seedlings exhibited greater satisfactory photosynthetic acclimation, being able to have normal growth and regeneration.

Key words: Stellera chamaejasme population, Age structure, Root crown, Survivorship curve, Population regeneration