| As an important resource for human survival and development, energy gives great impetus to society and economic development. With the world economic development and population growth, resource shortage has become the main limiting factor of world economic development. A large-scale exploitation and consumption of fossil energy have led to resources reduction distinctly, and caused serious environmental pollution. However, the renewable energy development has become a necessary and urgent task. With higher biomass and less environmental pollution compared to mineral energy, renewable woody biomass energy has been paid more and more attention by many countries. Exploitation and utilization of woody biomass energy is at an early stage in China.With strong adaptability, rapid growth, sprouting ability and easy regeneration, Populus L. and Salix L. have great potential for development of high-yield and short-rotation energy plantation. For short-rotation energy plantation of polar and willow abroad, a lot of researches have been on selection and breeding, spacing density and rotation time, high-yielding cultivation techniques, pest and disease control, etc. Domestic researches on appropriate energy density and planting comprehensive of poplar and willow short-rotation energy plantations are still in its infancy and have been not reported yet. In this research 5 poplar clones and 4 willow clones were preliminary selected and firstly test on reasonable spacing density and rotation time for energy plantation in Jiao Zuo City, He Nan province. Moreover, combustion characters of poplar and willow clones were determined and analyzed. It was designed to provide some theoretical and technical basis for selection and breeding, spacing density and rotation time, high-yielding cultivation techniques of poplar and willow short-rotation energy plantations. There are main results as follows as these:1. Sprouting ability of poplar and willow clones were determined and analyzed. It was found that sprouts of poplar and willow for energy plantation were very few (only 1~3 shoots) in the first year and stumping after the first year would promote more sprouts and obtain higher biomass in the second year .2. Four willow clones were used and compared of biomass plantation after rotation time of 1 year and 2 years, with three spacing density of 10000, 15000, 30000 cutting/hm2. It showed that Salix integra, Salix×jiangsuensis CL'J-795', CL'J-799'and CL'J-172'are all suitable for rotation at two-year and density at 15000 /hm2, and their biomass are 11.27 t/(hm2·a), 8.43 t/(hm2·a), 6.10 t/(hm2·a),6.17 t/(hm2·a) respectively. 3. Five poplar clones were used and compared of biomass forest plantation after rotation time of 1 year and 2 years, with spacing density of 10000cutting / hm2. It was observed that biomass of P. deltoides Bartr cv.'55/65', P. deltoides×P. maximowiczii 110, P. deltoides 313, P. deltoides 239 and P. nigra×P. deltoides 2001 were respectively 13.72 t/(hm2·a), 15.27 t/(hm2·a), 13.93 t/(hm2·a),14.73 t/(hm2·a), 12.96 t/(hm2·a) at one-year rotation time. There was no significant difference within clones. Annual average biomass unit area of these clones after two-year rotation were respectively 16.15 t/(hm2·a), 13.92 t/(hm2·a), 13.52 t/(hm2·a), 13.06 t/(hm2·a), 12.95 t/(hm2·a) . It was also not found significant difference within these 5 clones. Annual average biomass unit area of P. deltoides Bartr cv.'55/65'was increased at two-year rotation comparing with that at one-year rotation. And for other four clones, it was reduced by a small margin at two-year rotation comparing with that at one-year rotation. Moreover, on 1 year of rotation time, biomass of the second rotation reduced by a small margin comparing with that of the first rotation comparing. There were small difference between 1 year and two years of rotation time. Therefore, it was more reasonable to choose two-year rotation than one-year rotation.4. Ash content and calorific value were determined for different component of poplar and willow clones on one-year and two-year rotation. It was found that ash content of two-year plants was lower than that of one-year plant, but calorific value of two-year plant were higher than that of one-year plant. Ash content of one-year and two-year poplar plants were 3.30%-6.43% and 2.93%-3.73%, respectively. And their gross calorific value were 18.63-19.28MJ/kg and 19.11-19.44MJ/kg, respectively. Ash content of one-year and two-year willow plants were respectively 3.93%-5.10% and 2.31%-3.38%. Gross calorific values were respectively 18.00-18.46 MJ/kg and 18.83-19.15MJ/kg.5. Ash content and gross calorific value were determined for different component of one-year rotation of poplar and willow clones. It was found that the order of the ash content in different components were bark> whole-tree > trunk for poplar and willow clones. Difference of gross calorific value was not significant among different components of same poplar clones. But there was significant difference among willow clones, and the order was trunk > whole-tree> bark.6. Test and analysis on planting density and rotation time were carried out for poplar and willow short-rotation energy plantations. Reasonable rotation time and planting density were primarily found and it also showed that in case of this cultivation condition biomass of poplar clones were more than that of willow clones and calorific value of dry mass of willow clones was generally higher than that of poplar clones. For the first time in China, this research carried out test on spacing density and rotation time of poplar and willow short-rotation energy plantation and determined combustion characteristics of poplar and willow clones on rotation time of 1 year and two years. The results filled the domestic gaps in the corresponding field of research and aimed at trying to establish efficient system of cultivation technology and provide technical and theoretical guidance for future development of poplar and willow short-rotation energy plantation in China. On the basis of this research, further test on rotation time of 3 year and determination of growth, biomass, ash content and calorific value and other traits will be started in near future. Moreover, the same test and determination will also carried out at different site. In the end, suitable rotation time would be finalized for poplar and willow short-rotation energy plantation in China. |
PDF Full Text Request