短周期尾巨桉能源林生物量与能量特征研究

为开发和利用尾巨桉能源林,通过测量1~4年生植株的叶片、树枝、树根、树干和树皮的热值和生物量,对短周期尾巨桉能源林的生物量和能量特征进行了研究。结果表明,尾巨桉叶片、树枝、树干、树根、树皮和林分生物量均随林龄增加而增加,叶片、树枝、树皮生物量占单株总生物量的比例逐年减小,而树干则呈逐年升高趋势。1~4年生尾巨桉单株和林分的生物量分别为4.32~66.29 kg和10.68~153.33 t hm-2。生物量的结构特征表明,尾巨桉林分在第4年开始郁闭,生长以增加树干的生物量为主。尾巨桉各组分的平均干质量热值为17.23~20.56 kJ g-1,且差异极显著(P<0.01),以叶片的值最高、树皮的最低;同一组分不同林龄的热值差异不显著(P>0.05)。1~4年生尾巨桉的单株和林分能量现存量为81.61~1255.22 MJ和201.83~2903.32 GJ hm-2,其变化趋势及大小排列顺序与生物量相同。因此,对尾巨桉能源林可以4年短周期进行经营。

Studies on Biomass and Energy Characteristics of Short Rotation Energy Plantations of Eucalyptus urophylla×E. grandis

In order to development and utilization of Eucalyptus urophylla × E. grandis plantation, biomass and calorific values of 1- to 4-year-old E. urophylla × E. grandis were determined to reveal biomass and energy characteristics of Eucalyptus at different ages. The results showed that the biomass of leaves, branches, stem, roots, bark and total biomass increased with increasing age. The ratio of leaf, branch and bark biomass to total biomass decreased with age, while the ratio of stem biomass to total biomass increased. Biomass of 1- to 4-yearold individual and stands ranged from 4.32 to 66.29 kg, and 10.68 to 153.33 t hm^-2, respectively. Biomass structure characteristics revealed that Eucalyptus plantation began to closure at the 4^th year, and stem growth was dominant. Gross calorific values had significant difference (P<0.01) among five components, such as leaf, branch, root, stem and bark, with ranged from 17.23 kJ g^-1 for bark to 20.56 kJ g^-1 for leaf, those of the same component had no significant differences among different ages (P>0.05). The retained energy of 1- to 4-year-old individual and stands ranged from 81.61 to 1255.22 MJ and 201.83 to 2903.32 GJ hm^-2, respectively, the change trend and orders of components were the same as biomass. Therefore, it suggested that E. urophylla × E. grandis energy plantation could manage with short rotation for 4 years.