Carbon storage allocation pattern of Casuarina equisetifolia Forst with different ages in Wenchang city of Hainan

Using the biomass estimation models of Casuarina equisetifolia, we studied the carbon storage and distribution characteristics of C. equisetifolia plantations in Wenchang with different forest ages. The results showed that, the carbon contents of each organ in the C. equisetifolia was in 454~526 g/kg, the average carbon content in each component was: root ＞ leaf ＞ fruit ＞ trunk ＞ branche ＞ bark. The carbon contents in 0-60 cm soil ranged from 0.8 to 9.3 g/kg, and the average carbon content was only 3.6 g/kg. There was significant difference about the carbon content in different soil layers with the same forest age, and the rate of soil carbon content increased with the forest age. Carbon storage order of arbor layer in different forest ages was: over-ripe forest (233.1 t/hm2)＞ mature forest (165 t/hm2)＞ near-mature forest (99.8 t/hm2)＞ middle-aged forest (56.0 t/hm2)＞ young in the aged forest (27.1 t/hm2). The carbon storage of the same organ in different forest ages showed significant differences (P＜0.05), and there was no significant difference between branches and leaves of the middle-aged forest and the near-maturing forest, but there was significant difference among different organs at different ages (P＜0.05). The order of soil carbon storage in different forest ages was: mature forest (34.27 t/hm2)＞ near-maturing forest (22.97 t/hm2)＞ over-ripe forest (20.8 t/hm2)＞ middle-aged forest (15.92 t/hm2)＞ young Lin (12.27 t/hm2), and the same forest age in 0 ~ 10 cm, 10 ~ 20 cm, 20 ~ 40 cm soil layer showed significant differences (P ＜0.05). Besides, the same soil layer between the different ages of the forest was not significant one. The carbon storage in the arbor layer and soil layer werethe main carbon pools of the ecosystem. The carbon storage of the arbors layer was the first carbon pool, which accounts for 79.85%.