| Global carbon cycle is a very important issue in the study of global climate change.Forest ecosystem carbon cycle is one of the important part of global carbon cycle, but at the present time there are considerable uncertainties in the research of global carbon cycle, in forest ecosystems carbon cycle research, which especially in the estimation of carbon storage of region forest ecosystems and CO2 fluxes exchanging with other systems. Accurate estimation of the carbon storage and CO2 fluxes and reduce the estimation uncertainties for region forest ecosystems are the hot and difficult problems. This paper take the broad-leaved,Everglade pine,Masson pine, Chinese fir,Coniferous mixed forest,broad-leaved mixed forest,Bamboo forest,Fruit srand, brush and the broadleal forest,Land garden of main forest types in Guangzhou City as object of study. These forest type's carbon concentration in different organs, region forest ecosystem carbon storage size, carbon balance, carbon flux have been researched mainly. In order to estimate the function precisely of region forest ecosystem in carbon balance of Guangzhou, Seeks for the way to reduced the uncertainty aspacts in forest ecosystem carbon circulation research, The main results are as followingFirst, through potassium dichromate and vitriol oxidation, carbon concentration of ten forest types in Guangzhou city was measured and the variation character of it was analyzed. This research shows that carbon content of forest vegetation ranges from 40.06% to 54.5%, and carbon content of arbor layer is the largest, second is litter layer, and the least is vegetation layer under canopy. Coniferous forest has higher carbon content than broad-leaved forest. It also suggests that there are some variations for carbon content among different organs in arbor layer and among forest types.Second, according to the data in correlative referrences and forest resource inventory, it is mainly reckoned that carbon storage in vegetation, litter fall above and under ground, and soil of ten forest types in Guangzhou city. Results indicate that carbon storage in forest ecosystems is in the order as:soil layer>vegetation>litter layer above and under ground. And root makes up 0.29%～2.82% of total tree carbon, therefore it plays an impotant role in the carbon cycle of forest ecosystems.Third, total carbon density of forest in Guangzhou city is 83.25～126.24 tC·hm-2, which includes vegetation (11.26～18.85 tC·hm-2), litter fall (0.62～5.63 tC·hm-2), soil layer (68.63～107.25 tC·hm-2). It suggests that soil layer contributes 78%～88%.Fourth, according to the formula on carbon equilibrium of forest ecosystems, it shows that broad-leaved forest has the largest annual net stored carbon (3.52 t·hm-2·a-1) and it has the strongest effect to store carbon. Second is coniferous and broad-leaved mixed forest (2.79 t·hm-2·a-1). Shrubbery appears weak to store carbon. Whereas, city gardens and bamboo become the carbon source. The annual net stored carbon in litter layer has significant relativities with carbon budgets and fiercely affects carbon equilibrium of forest components.Fifth, It is studied that the biomass of ten forests in Guangzhou city in 2006 is increasing. The net increment is 1.76～3.32 t·hm-2·a-1. And the biomass of litter fall is 0.62～5.63 t·hm-2·a-1. The respiration of vegetation in communities is 2.72～7.48 t·hm-2·a-1, and soil heterotrophic respiration is 1.72～5.43 t·hm-2·a-1. Global primary production in ecosystem is 5.97～16.43 t·hm-2·a-1 and net primary production is 3.25～8.95 t·hm-2·a-1.
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