不同年龄阶段杉木人工林植物热值分析

The plant calorific values in the Chinese fir (Cunninghamia lanceolata) plantations at different ages

应用会同国家野外科学观测研究站的连续定位测定资料,研究了杉木林不同林龄阶段乔木、灌木、草本和枯死物热值动态变化。结果表明:同一林龄阶段,杉木叶的热值>皮>枝>干>根,杉木各器官热值随林龄增加而增大;相同林龄的灌木叶热值>枝>根,草本地上部分热值>根,灌木和草本的热值随林龄增大而减少;同一林龄的凋落叶的热值>凋落枝>碎屑>死根,枯死物热值随林龄增加而增大;整个杉木林系统,乔木层热值>灌木>草本>枯死物;灰分含量与会同杉木器官热值的大小与变化关联性不密切,与灌木、草本呈显著负相关(P<0.05);会同杉木热值随林龄变化与器官随林龄增大木质化程度提高,以及不同年份的降水量、太阳辐射、温度有关;林分不同层次植物热值的变化与某个层次的植物接受的光能资源量关系密切。

As a principal timber species, Chinese fir （Cunninghamia lanceolata （Lamb.） Hook ） is widely planted throughout southern China and it covers approximately 9.21 million hectares, almost one third of total plantation in China and it contributes greatly to meeting the expanding timber demand. The heat value of the tree represents, to some degree, the capacity of the physiological function and productivity of the plant. In this study, the calorific values of plants in Chinese fir （Cunninghamia lanceolata） plantation at different ages were studied, based on located observations from a national key field scientific experimental station in Huitong, Hunan Province, China. The biomass, carbon concentration of different component of the tree, understory vegetation and dead litter layer were investigated at 11-year, 14-year, 18-year, 20-year old Chinese fir plantation. By using the six standard tree method, the allometric equations for biomass were established for the Chinese fir plantations at different stand ages, including the trunk, leaves, barks, twigs and roots. The dry matters were ground and the calorific value of different component of the plant and ecosystem were measured with automatic calorimeter （WZR-1TC U ）. We analyzed the data with one-way ANOVA, two-way ANOVA and Duncan by using SPSS 13.0 and the results showed that at the same age, the different organs of Chinese fir had different calorific values, they shared a similar pattern and in a small range, between 17.3 to 20.6 J/g and ranked as needle〉 bark 〉 twig 〉 trunk 〉 root. As to the different organs of Chinese fir, the calorific values increased with the age. At the same age, The calorific values of shrubs was in the order needle 〉 twig 〉 root. For The calorific values in aboveground organs of herb was higher than that of root. Over time, calorific values in shrubs and herb decreased with the age. At the same age, the calorific values of litter was in the order needle 〉 litter twig 〉 detritus 〉dead roots. The calorific values of the litter components increased with the age. As to Chinese fir plantation ecosystem, the calorific values of the components was in the order of tree layer 〉 shrub layer 〉 herb layer 〉 litter layer. There was no robust relationship between ash content and calorific values in the different organs of Cunninghamia lanceolata, but that of the Shrubs and herb organs has a significantly negative correlation with its ash content （ P〈0. 05）. The Calorific value of organs of Cunninghamia lanceolata changed with the age, which might affect the organs of Chinese fir with stand age, the increased lignifications for instance. Furthermore, the environmental factors could also contribute to the calorific values over time, such as the rainfall, solar radiation, temperature, and so on, in that the calorific values of plants in Chinese fir plantations, the components beneath the system will be affected by the receiving resources for solar energy for different plants located in the different layer, which could also be true even in the different layers of leave~ for Chinese fir itself.