Abstract: The study based on HNSOTER and supported by GIS showed that in Hainan Island, the total amount of soil organic carbon in the standard profile depth of 0~100 cm was about 2.78×10⁸ t, and the soil organic carbon density in 0~20 cm and 0~100 cm profile depth was 0.3~18.8 kg·m^-2 and 1.0~32.1 kg·m^-2, with an area-weighted means of 3.3 kg·m^-2 and 8.4 kg·m^-2, respectively. Soil organic carbon density varied significantly with different landform, lithology and soil, which tended to decrease from the mountains in the middle part of Hainan Island to its coastal plain, and had some differences between 0~20 cm and 0~100 cm profile depth. The areas of high soil organic carbon density in 0~20 cm profile depth were mainly distributed in the mountains and northern basalt tableland, while those in 0~100 cm profile depth were in the middleeastern mountains and tableland. The distribution center of soil organic carbon density in 0~100 cm profile depth had a significant shift to the eastern part, compared with that in 0~20 cm profile depth.

Key words: Species diversity, Species richness, Ecosystem function, Degraded ecosystems