Abstract:To explore ecophysiological variances and their sources among different geographical origins of Quercus variabilis, a reciprocal transplanting experiment was carried out at its northern (Beijing) and southern (Kunming, Yunnan Province) distributed edges at the end of April 2013. The seedlings were bred from seeds collected from three provenances: north (Pinggu in Beijing, NP), central (Huanglong in Shanxi Province, CP), and south (Anning in Yunnan Province, SP) in the autumn of 2012. After three months of acclimation, we measured two response curves, A-Par and A-Ci. More specifically, A-Par calculated light response parameters, including apparent quantum yield, AQY; maximum net photosynthetic rate, Pmax; light saturation point, LSP; light compensation point, LCP; and dark respiration rate, Rd. A-Ci measured CO2 response parameters, including carboxylation efficiency, CE; maximum net photosynthetic rate, Amax; CO2 compensation point, CCP; and photorespiration rate, Rp. The proceeding values were all measured using the Li-6400 gas analyzer. Relative chlorophyll content was calculated with the SPAD-502 analyzer, and chlorophyll fluorescence parameters, including primary conversion of light energy of photosystem Ⅱ, Fv/Fm; potential activation of photosystem Ⅱ, Fv/Fo; the non-photochemical quenching coefficient, NPQ; and photochemical quenching coefficient, PQ, were measured with the Fluropen-FP100 at the two distinctive habitats during the mid-growing season (August 15-30). In addition, growth rate (height and ground diameter) was measured. Our results showed that (1) the seedlings growing in the north habitat presented significantly higher P < sub>max, LSP, CE, PQ, and Rp than in the south habitat (P < 0.05). (2) In both habitats, the SP had higher CE, LSP, Fv/Fm, Fv/Fo, with an order of SP, CP, and NP, while the NP had higher NPQ, with an order of NP, CP, and SP. (3) The interaction of habitats and provenances significantly affected Amax and LSP. Furthermore, the highest Amax occurred in the local provenance over the two habitats. The CP and the NP exhibited the highest LSP in the north and south habitats, respectively. Between the two different habitats, there were significant differences in AQY, CCP, Rd, Fv/Fm, Fv/Fo, and NPQ. There was no interaction of habitats and provenances found on AQY and Rd, which may indicate the determination of species genetic background. (4) Relative growth rates were significantly different between the two habitats with a higher growth rate in the north habitat for all tested provenances, and the SP consistently had the highest relative growth rate. In conclusion, our results suggest that, to varying degrees, the two distinctive habitats and the interaction of habitats and provenances affected the growth and photosynthetic characteristics of Q. variabilis seedlings. We preliminarily deduced that the SP could be well adapted to the northern habitats.