Two widely planted poplar species Populus balsamifera L. (Da) and Populus euramericana cv (I 467) were used to investigate chlorophyll fluorescence (F) characteristics to reveal their intrinsic ecological adaptability during long term adaptation to the ambient environment by chlorophyll fluorescence dark adaptation and light adaptation experiments. The result showed that the change trend of chlorophyll fluorescence under darkness was similar and the change trend of chlorophyll fluorescence under lightness was different. The photosynthesis reaction center of I 467 absorbed excess light energy(E) to use more non photochemical process such as heat dissipation than Da, correspondingly reduced for photochemical quenching share. Excess absorbed light energy and the light sensitive index (S) of Da were higher than those of I 467. Cancelling illumination conditions, the chlorophyll fluorescence of two poplar species initially recovered quickly, and then the speed of recovery gradually slow down. Da adapted to strong light, but I 467 adapted to low light and fast light changes. The experiment results showed that Da was better able to adapt to the strong light of energy utilization. Da was suitable as the fast growing forest tree species to using radiation in Xinjiang Ili Valley for afforestation. .
