Abstract:It is of great significance to study the carbon storage changes of rubber forest (Hevea brasiliensis) at different ages for understanding the carbon sequestration potential and carbon cycling process in rubber plantation ecosystems. Rubber forests of different ages (6, 12, 18, 23, 27, 35 years old) in Danzhou City, Hainan Province were studied to analyze the changes of tree layer, understory vegetation, litter, soil and ecosystem carbon storage during the growth of rubber forests, and compare the carbon sequestration rate and carbon sequestration potential of rubber forest ecosystems. The results showed that the carbon stock in the tree layer ranged from 14.87 to 63.53 t C/hm2, in the order of 35->27->23->18->6-years old. The carbon stock of understory vegetation ranged from 0.30 to 0.75 t C/hm2, and which at 35 years old was significantly higher than that of other stands. The litter carbon stock ranged from 1.72 to 2.03 t C/hm2, and which in the 18- and 35-year-old forests were the highest. Soil carbon stock varied from 81.21 to 156.68 t C/hm2 in the order of 27->18->23->12->35->6-years old. During the life cycle of 35 years, approximately 25.27 t C/hm2 of carbon was fixed in the soil, and there is a transition process from carbon fixation to carbon emission. The total carbon stock of rubber forest ecosystems ranged from 98.30 to 214.74 t C/hm2 in the order of 27->18->23->35->12->6-years old. Notably, the carbon storage of 6-years old plantation was significantly lower than that of 27-years old mature plantation. Carbon storage in soil and tree layer was an important carbon reservoir of rubber forest, accounting for 68.16%-91.27% and 16.71%-40.59% of the total ecosystem carbon storage, which in litter was less than 2.1%, and that in understory was less than 1%. Rubber forest ecosystem had a high carbon sequestration rate and carbon sequestration potential, which was an ideal tree for building efficient carbon sequestration plantation and promoting regional effective emission reduction strategy.
