To understand responses and adaptation of tree photosynthesis to environmental changes, we conducted a provenance experiment on Dahurian larch (Larix gmelinii Rupr.), the dominant boreal tree species in northeastern China. Seeds, collected from six provenances with significantly different geographical and climatic conditions, were planted 26 years ago at a homogenous site in the southern boundary of the distribution range of this species. Our objectives were to examine variations in the photosynthetic capacity and related variables for the larch trees from the six provenances, and to explore effects of provenances on changes in these variables with canopy positions and months. The light-saturated net photosynthetic rate (Pmax), apparent quantum yield (AQY), leaf mass per area (LMA) and area-based leaf nitrogen concentration (Na) were significantly different (p<0.05) among the provenances, varied from 6.10-8.78 μmol CO2·m-2·s-1, 00325-0.0427 μmol CO2·μmol-1photons, 85.1-114.3 g·m-2, and 1.72-2.26 g·m-2, respectively. The light compensation point (LCP), light saturation point (LSP), dark respiration rate (Rd) and area-based chlorophyll concentration (Chla), however, did not differ significantly among the provenances, averaging 61.2 μmol photons·m-2·s-1, 1093 μmol photons·m-2·s-1, 2.34 μmol CO2·m-2·s-1 and 0.12 g·m-2, respectively. The Pmax, Chla, Na and LMA were significantly positively correlated to each other (p<0.001). The Pmax, LCP, Na and LMA tended to increase with canopy positions from bottom to top, which was significantly influenced by the provenances. The provenances did not significantly affect monthly changes in the photosynthetic capacity and related variables except AQY. The variables examined mostly showed a bell-shaped pattern with their maxima occurring in August. The significant variations in the photosynthetic capacity and some related factors from the six larch provenances suggest an evident ecophysiological adaptation of photosynthesis to their original environmental conditions.