Study on Biomass and Energy of Two Different-aged Eucalyptus Stands

The biomass and energy of two different-aged Eucalyptus stands in Lianjiang city, Guangdong Province were studied. The results are as follows: The total retained biomass of plantation and the total biomass of various organs increased as the stand ages increased. The biomass of various organs were different, the stem’s biomass was the highest while the leaf’s was the lowest among five organs of different stand ages. The total retained biomass of 4.5-year-old E. leizhouensis No.1 and E. urophylla×E. grandis plantation were 77.13 t·hm-2 and 80.03 t·hm-2. The ash content (AC), gross caloric values (GCV) and ash free caloric values (AFCV) of various organs were different. The order of AC, GCV and AFCV of various organs were bark＞leaf＞root＞branch＞stem, leaf＞branch or stem＞root＞bark, leaf＞branch＞stem or root＞bark. The AC of leaf, branch, root and stem increased as the stand ages increased, the GCV of them changed oppositely. The AC of bark decreased as the stand ages increased, the GCV of them changed oppositely. The average of AC of individual had not a significant negative correlation with the stand ages, the average of GCV and AFCV of individual had not a significant positive correlation with the stand ages. The total retained energy of 4.5-year-old E. leizhouensis No.1 and E. urophylla×E. grandis plantation were 1 482.91 GJ·hm-2 and 1 515.06 GJ·hm-2. The energy of various organs at different ages changed and distributed as more or less with the biomass of plantation. The mean annual increments of the total retained biomass and energy of plantation of two Eucalyptus stands were the maximum in 3.5 years.