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The performance of 14 North American hybrid poplar clones was evaluated near Beijing in short-rotation plantations grown at a 1 x 1 m spacing. Significant clonal differences were found in eco-physiological and morphological characteristics. Clones DN-17, DN-2, DN-182, DN-14274, 328-162, and NM6 exhibited high emergence and survival rates, and DN-17, DN-14274, DN-182 and NE-222 had a short growing period. Other clones (306-45, 195-522, 184-411 and 328-162) had a long growing period and may be more suitable in southern China. Clones DN-2, DN-182, and 195-522, had the highest productivity and the best potential as biomass producers. Clones DN-14274, DN-17, DN-182, NE-222, and DTAC-7 allocated more belowground biomass than the other clones during the first growing season, indicating that they might be better adapted to arid regions such as those in northern China. Clones 195-522, 184-411, DTAC-7, NE-222, R-270 and 306-45 had a higher capacity for CO2 assimilation. Clones NE-222, 306-45, DTAC-7, 195-522, R-270, 15-29, and DN-17 had a higher photosynthetic potential and could potentially adapt to a wide range of environmental conditions. Clones 195-522, 184-411, 328-162, DN-182, and NM6 had higher water-use efficiency than the others, suggesting that they would utilize soil water more effectively, especially in the dry season and in arid regions. Clones R-270, DN-14274, 15-29, DN-2, and DTAC-7 had higher transpiration rates, indicating that they would require frequent irrigation in the dry season and in arid regions to ensure normal survival and growth. (C) 2011 Elsevier Ltd. All rights reserved.