Primary Studies On The Planting Density Of Several Main Tree Species Of Energy Plantations On Different Sites

In this paper, Salix spp., Robinia pseudoacacia,Lespedeza spp. and Amorpha fruticosa which showed fast growing, high calorific value, high yield, large sprouting amounts, strong adaptability,etc. property were studied .Energy tree species were planted in different planting density ,which will provide the highest biomass in different Site condition, provide theoretic basis and technical guide for energy forest development ,and promote sustainable utilization of energy resources and sustainable development of society in china.The main research results were as follows:(1) In rocky land in Beijing ,biomass of pseudoacacia'shandong No.10'with density of 68243 tree/hm² was the highest of the energy tree species,was 28.3 t / (hm²Â·a) and were 17%-101% more than other different density. Salix×jiangsuensis CL 'J-172' with density of 200000 tree/hm² was 14.1 t / (hm²Â·a) and was increased by 12% - 570% than other different density. Compared with by document date , Salix×jiangsuensis CL 'J-172' and pseudoacacia'shandong No.10'with different planting density reached a fairly high level in that site condition.Comprehensive comparison fitting single-stem biomass, LnW_枝=-1.429+0.8621nH +2.0061nD of non-linear regression model was the best, R²=0.965. W=40. 073-110. 164D+107. 931D²-17. 866D³ W=-34. 458+35. 013D+17. 865D² W=21.127 D^2.353 and W=e^{6.395-3.478/D} of curve regression model are fairly good. These models in calculation is simple , and were convenient and high precision.(2) In the plain fertile soil in beijing , biomass in energy usage of the provenance from xifeng1,2 in liaoning of Lespedeza cyrtobotrya at three age with density of 111111 tree/hm² was the highest of the energy tree species, were 39.6 37.0 t / (hm²Â·a) and xifeng2 in liaoning of Lespedeza cyrtobotrya were 99% - 2026% more than other energy tree species. And their feeding biomass were also the highest of the tree species, were 17.4 18.01 /(hm²Â·a)andthe provenance 2 of Lespedeza cyrtobotrya were 31%-2026% more than other tree species. Biomass in energy usage of Lespedeza bicolor cradling one time a year with density of 20408 tree/hm² was 31.2 t / (hm²Â·a) and was increased by 217%—238% than other different density . And its feeding biomass was 21.71 / (hm²Â·a) and was increased by 247% 255% than other different density .Biomass of pseudoacacia'henan No. 8048 'with density of 111111 tree/hm was 20.9t/(hm²Â·a) and was increased by 217%—238% than other different density.In primary growth stage ,bud picking are favorable to pseudoacacia energy forest ,the number of left buds was 1 -2. Comprehensive comparison,cubic equation model(w=-16. 113-43.380D+97.559D²-3.633D³), quadratic equation model (w=-31. 983-11. 924D+78. 410D²), power curve model(w=33.125 D^2.907) and S type curve model(w=e^{(7.632-4.149/D)} of curve regression model in fitting single-branch biomass model are fairly good, R²>0.941, measure factors was only diameter. Multiple linear regression model (W_总=-506. 820+258. 713D_u+0. 146nH_u+0. 721H_u)of fitting simple bundle biomass model are good, R²=0.915, measure factors was only dominant single stem in simple bundle.(3) In the sandy soil in Shandong Province,biomass of Amorpha fruticos ,which was 50cm×50cm of spatial allocation and 2 trunks per hole, was the highest in 6 different planting ways, was 5. 0 t / (hm²Â·a) and were 51%—219% more than other different planting ways with 2 trunks per hole.(4) Different energy tree species with reasonable planting density were chosen in different site condition .Biomass of the provenance from xifengl,2 in liaoning of Lespedeza cyrtobotrya ,at three age with density of 111111 tree/hm² ,was the highest were 39.6 37.01 / (hm²Â·a). Biomass of Lespedeza bicolor cradling one time a year with density of 20408 tree/hm² was 31.2 t / (hm²Â·a) , pseudoacacia'shandong No.10'with density of 68243 tree/hm² was 28.3 t / (hm²Â·a) , and pseudoacacia'henan No.8048'with density of 11111 ltree/hm² was 20.91 /(hm²Â·a). Comprehensive comparison, biomass of Amorpha fruticos , which was 50cm × 50cm of spatial allocation and 2 trunks per hole, was the lowest and was only 5. 0 t / (hm²Â·a) Different energy tree species with reasonable planting density were chosen in different site condition , and cultivation technology were summarized primarily in this study,which had great theroretical and realistic meaning. At last, it suggests that effective development energy forest are very important in China, and continue strengthening research development and utilization of energy forest are very necessary. It is the important ways to solve the problem of China's energy resources security and environmental pollution and will play important role in the improvement of ecological environment.