Abstract: [Objective] To find a suitable spacing configuration with which more dry biomass of poplars can be harvested in a short period of time, we conducted a study on photosynthetic characteristics and growth of a 2-years-old new variety of poplar (Populus×euramericana. ‘Bofeng 3) for pulpwood production under short rotation management in this article.[Method] The forest micro-environment, photosynthetic characteristics and growth of poplar in the plantation with 3 spacing configurations (row spacing×plant spacing, treatment 1:120 cm×30 cm, treatment 2:40 cm×90 cm, treatment 3:60 cm×60 cm) were investigated.[Result] 1) Results showed that seedling height and collateral number in treatment 1 were significantly higher and more than those in treatment 2, and the leaf area per plant and collateral branch length were significantly greater than those of treatment 3 and treatment 2. The dry biomass yield in unit area in the all 3 configurations was more than 3.00×10⁴ kg·hm^-2. The biomass yield in treatment 1 was about 4.23×10⁴ kg·hm^-2, and was significantly higher by 24.41% and 17.50% than that in treatment 2 and treatment 3, respectively. 2) The stand micro-environment was affected by different spacing configurations. An appropriate increase in row spacing and decrease in plant spacing were able to increase density of C_a, canopy temperature (treatment 1 > treatment 3 > treatment 2) and reduce canopy related humidity (treatment 1 < treatment 3 < treatment 2). 3) Variation of micro-environment in different configuration forests influenced differentially photosynthetic characteristics. The diurnal variation of net photosynthetic rate (P_n) of the variety in all three configurations showed a bimodal curve, the daily accumulation of P_n (165.66 μmol·m^-2d^-1) in treatment 1 was 7.03% higher than treatment 2 (P<0.05). 4) Correlation analysis showed that dry biomasses of aboveground part were both significantly or very significantly (P<0.01) correlated to seedling height, leaf area per plant, PTL and daily accumulation of photosynthesis per plant, and seedling height was significantly correlated to diameter at breast height.[Conclusion] The results suggest that proper adjustment of spacing configurations of the short-rotation forests with high density can improve micro-environment and increase photosynthetic potential of Populus×euramericana ‘Bofeng 3’, then affect plant growth, finally influence the accumulation of aboveground dry biomass. For a rotation of two years, the configuration (120 cm×30 cm) can obtain the maximum biomass of P.×euramericana. ‘Bofeng 3’ and the configuration shows a certain promotional value.

Key words: poplar, short-rotation plantation, spacing, growth, photosynthesis characteristics