Biomass production and bark yield in the plantations of Pteroceltis tatarinowii

The bark of Pteroceltis tatarinowii is the main raw materials for manufacturing Xuan paper. With the increasing of Xuan paper-making factories, greater demands for bark production will be placed on the new plantations of P. tatarinowii. The objective of this study was designed to investigate the effects of site factors and silvicultural regimes on above-ground biomass production and bark yield of P. tatarinowii plantations. Based on the investigation of 33 plantations of P. tatarinowii, the results indicated that significant differences in above-ground biomass and bark yield among the sites were observed. The ranking of the biomass production and bark yield by rock is slate>phyllite>limestone>sandstone. The average above-ground biomass on the sites with top soil more than 20 cm is 1.45 times of that on the sites with top soil between 10 and 20 cm, and 1.56 times of that on the sites with top soil less than 10 cm. Similar to the above-ground biomass production, the bark yield increased with the increment of top soil depth. Correlation analysis suggested that organic matter, total N, available K and available P were positively related to above-ground biomass production and bark yield, while C/N was negatively. Significant differences in above-ground biomass, bark yield and bark ratio among four planting densities were observed. The highest biomass was achieved at the plantation of 3333 stumps/ha, while the highest bark yield occurred at the plantation of 4200 stumps/ha. In the coppice system of P. tatarinowii plantations, the biomass production and bark yield are significantly affected by stump age, sprout age (rotation length), and the number of sprouts per stump. This investigation indicated that the coppiceability of P. tatarinowii is vigorous and the stumps tend to be long-lived. In term of biomass production and bark yield, 3333–4200 plants/ha as initial planting density, 3-year rotation and 8–12 sprouts per stump are suggested for practical use in establishing the coppice system of P. tatarinowii plantations.