不同林龄史密斯桉灰分、热值、挥发分和固定碳比较研究

对2~6年生史密斯桉的叶片、树枝、树根、树干、树皮5个部位进行灰分、热值、挥发分和固定碳测定。结果表明：不同林龄史密斯桉5个部位的灰分含量在0.41％~5.48％，以叶片、树皮的较高而树干的最低；干质量热值与去灰分热值分别介于16.53~22.60 kJ/g与17.48~23.81 kJ/g，均以叶片的值最高、树皮的最低，树枝、树根、树干介于二者之间；挥发分含量为68.35％~85.65％，均以树干的含量最高、树皮的最低；固定碳含量在13.95％~27.13％，以树皮的含量较高、树干的最低。5个部位林龄间的灰分、干质量热值、去灰分热值、挥发分与固定碳差异程度不同，按林龄排序结果均无一相同，未呈现随林龄增长而各测试指标数值明显变化的规律。相关分析表明，林龄与植株体灰分含量呈显著负相关（p<0.05），与植株体干质量热值、去灰分热值、挥发分、固定碳的相关性不显著（p>0.05）。

Ash Content,Caloric Value,Volatile and Fixed Carbon of Eucalyptus smithii at Different Stand Ages

Ash content,caloric value,volatile and fixed carbon of leaves,branches,roots,stem-wood and bark of 2~6 years old Eucalyptus smithii were determined.The results showed that ash contents of five parts varied from 0.41% to 5.48% with the lowest in stem-wood,while leave and bark was higher.Mean gross caloric values(GCV)and ash free caloric values(AFCV)of different parts ranged from 16.53 to 22.60 kJ/g and 17.48 to 23.81 kJ/g respectively with leaves having the highest GCV and AFCV and bark the lowest.Contents of volatile were 68.35%~85.65% with the highest in stem-wood and the lowest in bark.Contents of fixed carbon ranged from 1.395% to 27.13% with the lowest in stem-wood.The differences of five parts among stand ages on ash content,caloric value,volatile and fixed carbon were different,their orders at different stand ages were quite different from part to part,the values of five test indexes didn’t change significantly with increasing stand ages.To the whole tree,results of correlation analysis showed that stand age was negatively correlated with ash content(p<0.05),but the correlations with caloric value,volatile and fixed carbon were not significant(p>0.05).