Abstract: Addressing the urgent need to transform rubber plantations pattern in Hainan Island and solve the problem of enhancing ecosystem carbon density in rubber plantations under compound management patterns, seven typical compound management patterns of rubber plantations in Hainan Island were selected as research objects, including Hevea brasiliensis + Michelia macclurei, Hevea brasiliensis + Alpinia oxyphylla, Hevea brasiliensis + Alpinia katsumadai, Hevea brasiliensis + Pandanus amaryllifolius, Hevea brasiliensis + Theobroma cacao, Hevea brasiliensis + Coffea arabica, and Hevea brasiliensis + Cinnamomum cassia. The results showed that: (1) Compared with pure rubber plantations, ecosystem carbon density of rubber plantations under compound management patterns in Danzhou and Wenchang were significantly increased. (2) In Danzhou, ecosystem carbon density under compound management patterns followed the order of Hevea brasiliensis + Cinnamomum cassia pattern (213.3 ± 9.45 t·hm^-2, with a carbon sequestration potential of 19.73 t·hm^-2); Hevea brasiliensis + Alpinia oxyphylla pattern (201.51±15.29 t·hm^-2, with a carbon sequestration potential of 7.94 t·hm^-2), Hevea brasiliensis + Pandanus amaryllifolius pattern (200.37±9.60 t·hm^-2, with a carbon sequestration potential of 6.80 t·hm^-2), and Hevea brasiliensis + Coffea arabica pattern (199.23±8.46 t·hm^-2, with a carbon sequestration potential of 5.66 t·hm^-2). (3) In Wenchang, ecosystem carbon density of rubber plantations under the Hevea brasiliensis + Michelia macclurei pattern was significantly increased (198.07±18.37 t·hm^-2, with a carbon sequestration potential of 38.76 t·hm^-2). These results provide a theoretical basis and technical support for forest transformation and carbon sequestration of rubber plantations under compound management patterns in tropical areas.

Key words: compound management pattern of rubber plantation, ecosystem carbon density, soil organic carbon density, carbon sequestration potential, Hainan Island