Poplar Clones And The Chongyang Wood Wood Energy Traits

The growth,biomass,photosynthetic rate,leaf area,contents of soluble sugar, crude fat,cellulose,lignin,C,N and S,wood density,calorific value and ash content for 25 hybrid poplar clones and 14 introduced poplar clones were investigated,as well as the coppicing techniques of Chinese Bishopwood(Bischofia polycarpa) plantation and its energy properties were also analyzed in this paper.Through the comprehensive analysis on growth,wood properties and energy index,we primarily evaluated the fitness of these tested poplar clones and the feasibility of Chinese Bishopwood both as woody bioenergy.The object of this study is to provide a theoretical basis for breeding and silviculture of energy forest.The main experimental results are as follows:1)The growth dynamic of both seedling height and base diameter for tested poplar clones showed "slow-fast-slow" annual growth rhythm and Logistic equation could best describe the annual growth dynamic,which could be divided into three phrases,i.e.,Pre-growing stage,Fast-growing stage,and Post-growing stage.For the 25 hybrid poplar clones,the results showed that there were significant differences in stem biomass,root biomass,bark biomass and total biomass among the hybrid poplar clones,where clone Y11 had the highest stem biomass and clone Y20 came to the next,while clones Y11,Y20 and Y4 were ranked as top three in the total biomass. For the 14 introduced poplar clones,the results showed that clones I,L and H were the highest in the total biomass.2)Poplar clones showed high net photosynthetic rate and transpiration rate. There were significant differences in net photosynthetic rate,transpiration rate,stomata conductance and intercellular CO₂ concentration among the poplar clones. Net photosynthetic rate exhibited a significant correlation with the growth of seedling height,base diameter,and biomass production.In the diurnal variations,net photosynthetic rate for all clones reached peak at nine o'clock in the morning,while the highest net photosynthetic rate was observed in clone Y11,reaching 18.4μmol·m^-2·s^-1;In the seasonal variations,net photosynthetic rate was high in May and reached peak in July.The highest net photosynthetic rate also occurred in clone Y11,getting 22.8μmol·m^-2·s^-13)The significant differences in wood basic density were observed among different poplar clones.For 25 hybrid poplar clones,there were 6 poplar clones that the wood basic density was above 0.28g/cm³(Y20＞Y22＞Y2＞Y4＞Y16＞Nanlin-95), whereas for 14 introduced poplar clones,the 6 clones where wood basic density was over 0.28g/cm³ were clones K,G,H,I,B and L(K＞G＞H＞I＞B＞L).4)There were significant differences in the crude fibre content,lignin content, alcohol benzene extractive content,soluble sugar content,crude fat content and ash content among poplar clones.For the tested 39 poplar clones(including 25 hybrid poplar clones,and 14 introduced poplar clones),the results showed that the contents of crude fibre and lignin were the highest in stem,next in root and bark,and the lowest in leaf.Compared to the other poplar clones,the crude fibre content in seedling stem was relatively higher in clones Y21,Y20,Y22,Y1 and Y19 (Y21＞Y20＞Y22＞Y1＞Y19)in 25 hybrid poplar clones,while the lignin content in seedling stem of the clones was in the order of clones Y22＞Y19＞Y1＞Y18＞Y17).However,for 14 introduced poplar clones,the crude fibre content in the seedling stem of clones B,K,I,H and G was relatively higher(K＞H＞I＞G＞B),while the lignin content in the stem of clones was in the order of clones G＞K＞H＞I＞B＞E.Ash content and alcohol benzene extractive content appeared significant differences in the different organs,in which the highest was observed in leaf,and lowest in stem.The range of the crude fat content in stems ranged from 2.22%to 2.71%.The significant differences in crude fat content and soluble sugar content were also detected among 14 introduced poplar clones.5)Significant differences in C,N and P contents were founded among different organs for tested poplar clones.As a mean,C content was about 50%in the organs, in which the highest C content was observed in bark,next in stem and leaf,and the lowest in root.Ash content also appeared significant differences in different organs. The highest Al and Fe contents were measured in root;but the highest contents of Ca,Cu,K,Na,Mg and Si were observed in leaf for different organs,and the lowest was in stem.6)For all tested poplar clones,the highest gross caloric value was measured in stem,then in root and bark,and lowest in leaf.For 25 hybrid poplar clones,the highest gross caloric value in stem,root,bark and leaf were observed in clones Y19,Y14,Y16 and Y9.Among the different organs of all poplar clones,the order of ash free caloric value was in the order of leaf＞bark＞stem＞root.For 25 hybrid poplar clones,8 clones had higher gross caloric value in stem(Y19＞Y17＞Y22＞I-72＞Y1＞Y7＞Nanlin-95＞Y5),while among 14 introduced poplar clones,6 clones had higher gross caloric value in stem(K＞I＞G＞H＞B＞E).7)By the factor analysis,the principal component analysis and cluster analysis, this study showed that clones Y11,Y20,Y4,Y22,Y14,Y19,Y16,Y17,Y10 and Y7 displayed the quick growth and the high gross caloric value among 25 hybrid poplar clones,which appeared better comprehensive character for woody bioenergy. However,the order of better comprehensive character among 14 introduced poplar clones was I＞L＞H＞A＞K＞E＞B＞G.8)The study on coppicing techniques of Chinese Bishopwood plantations indicated that there was no significant difference in tree height growth between the different numbers of sprout on each stump;but the sprout numbers on each stump had a significant effect on the base diameter growth of sprouts.From the view of above-ground biomass production(stem+branch),there were no significant differences in accumulative biomass production within 2-year growing seasons among the different management patterns.The highest above-ground biomass production(stem+branch)was measured in the plantation with 4 sprouts on each stump at the end of the second year,reaching 50360 kg/hm²,which was 7.4%,2.1% and 5.7%higher than the plantations with 1 sprout(cl)and 2 sprouts(c2)on each stump,and 2-year old plantation with 1 sprout(ck),respectively.9)The positive relationships between the contents of C,crude fibre and lignin, and gross caloric value were observed in the plantation of Chinese Bishopwood. There were no significant differences in the contents of C,crude fibre and lignin, and gross caloric value among the Chinese Bishopwood plantations with different sprouts on each stump,while a significant difference was observed between the stem ages of the plantations.The result mentioned above would give some reference for the management and utilization of the Chinese Bishopwood plantation in the future.