Abstract: Pinus yunnanensis forest is an important component of coniferous forest ecosystems on Tibet Plateau. To accurately estimate the carbon storage of the P. yunnanensis forest ecosystem is of significance to understand the carbon sequestration of forest ecosystems in Tibet, and also, to provide basic data for estimating the carbon sequestration potential of forest ecosystems on Tibet Plateau and in China. In this paper, an investigation was conducted on the biomass and carbon storage of the P. yunnanensis forest of different ageclasses. Based on the data from twelve sampling plots and forty seven sample trees, the biomass regression equations of each organ (leaf, branch, stem, and root) of P. yunnanensis based on tree height and diameter at breast height were established. Then, the biomass and carbon storage of young, middle age, premature, and mature P. yunnanensis forests were calculated. The results showed that the exponential model was an appropriate regression model for estimating the biomass of each organ based on the tree height and the diameter at breast height of P. yunnanensis (R²>0.90). The total vegetation biomass of the young, middleage, premature, and mature P. yunnanensis ecosystems was (63.80±9.21), (134.76±12.69), (142.91±13.02), and (316.72±42.57) t·hm^-2, of which, the biomass of tree layer was (49.48±10.32), (120.57±9.37), (124.70±12.92), and (304.76±32.47) t·hm^-2, the biomass of shrub and herb layer was (13.09±3.02), (12.81±2.54), (11.88±3.12), and (3.47±0.98) t·hm^-2, and the biomass of litter layer was (1.23±0.24), (1.38±0.31), (0.72±0.11), and (1.13±0.39) t·hm^-2, respectively. The carbon storage of the young, middleage, premature, and mature P. yunnanensis  forost ecosystems was (30.67±7.13), (67.63±19.06), (71.00±4.15), and (159.32±39.95)
t·hm^-2, respectively. The carbon storage of the P. yunnanensis forest increased significantly with its increasing stand age, indicating that Tibetan P. yunnanensis forest had great potential in carbon sequestration.

Key words: aboveground biomass, plant community height, estimate model, measuring plate.