Abstract:

The above-ground biomass production, distribution model, nutrients exported and wood quality characteristics of eastern cottonwood were studied in minirotation management systems among the combinations of 3 densities and 3 rotations, The stand, with planting density of 10000 plant·ha^-1 and 3 years rotation, could obtain the hightest biomass production 10.52t·ha^-1·a^-1 for clone I-69 and about 12.00t·ha^-1·a^-1 for clone NL-80351.The economic biomass production for pulp-making was also the hightest in the stand of 10000 plant·ha^-1 and 3-year-rotation, respectively 7.14t·ha·^-1·a^-1 for clone I-69 and 8.47t·ha^-1·a^-1 for clone 8.47t·ha^-1·a^-1. Nutrients exported from the minirotation management systems bear close correlation to the biomass production and distribution model. In the stand of 10000 plant·ha^-1 and 3-year-rotation, the amount of nutrients exported (N, P and K) were 33.97kg·ha^-1·a^-1 for clone I-69 and 38.50kg·ha^-1·a^-1 for clone NL-80351.However, the amount of nutrients exported for producing one metric ton of economic biomass was slightly lower for clone NL-80351 than for clone I-69.The timber produced from the minirotation management systems is a good pulp-making material, but the wood quality of clone I-69 is slightly superior to clone NL-80351.

Key words: Eastern cottonwood, Biomass production, Distribution model, Nutrients exported, Wood quality