Abstract: In this study, we selected three woody ecosystems (orchard wetland, orchard and green space), a herb ecosystem (farmland) and a river ecosystem, which were distributed in the TenThousandMu Orchard at Haizhu District, Guangzhou, to study their vegetation and soil carbon densities. The result showed that the ecosystem carbon densitis of orchard wetland, orchard, river, farmland and green space ranged from 137.49 to 208 t·hm^-2, and their soil carbon densities ranged from 98.45 to 196.44 t·hm^-2, and the carbon density of river sediment was far higher than that of the soils in the four terrestrial ecosystems (P<0.05). There existed significant differences between the vegetation carbon densities of the four terrestrial ecosystems, with orchard wetland (75.96 t·hm^-2) and orchard (65.53 t·hm^-2) being much higher than green space (36.69 t·hm^-2) and farmland (4.15 t·hm^-2) (P<0.05). The vegetation and soil carbon density of orchard, orchard wetland and green space constituted 40%-45% and 55%-60%, respectively, of the total carbon storage, whilst the soil carbon storage accounted for 95.01% of total carbon storage in the farmland, and the carbon of the river ecosystem was mainly distributed in its sediment (99.96%). In urban Guangzhou, the Ten-Thousand-Mu Orchard, a major green area containing large area of wetlands, has a high carbon density and a high level of carbon sequestration.

Key words: hydrological process, significance level, environmental change., hydrological variability, jump