Abstract: According to the data of the 6th Category Ⅱ Forest Resources Inventory in Changdu, we utilized the method of biomass expansion factor (BEF) to calculate the biomass. On the basis of combining the measurement of carbon content in the southeast of Tibet with related research in China, the carbon content of different tree species was determined, meanwhile the carbon storage, carbon density of forest and their spatial distribution pattern in Changdu were estimated. The results showed that the total carbon storage of forest in Changdu was about 1.058×10⁸ t, and the average carbon density was 67.31 t·hm^-2, being lower than that in Linzhi. The carbon storage of all forest types varied from 4.5×10² to 8.21×10⁷ t. The carbon storage of spruce forest occupied 77.82% of the total carbon storage in Changdu. The carbon density of all forest types was 19.88-81.16 t·hm^-2. From the age group, the carbon storage of mature and overmature forests occupied 77.91% of the total carbon storage of forest, and the carbon density of each age group increased with age. From the overall distribution pattern of forest carbon storage and carbon density, the forest carbon storage was the highest in Zuogong County, and the lowest in Dingqing County; the southern “Sanjiang” had the highest forest carbon storage, followed by the “Sanjiang” upstream region, and the lowest was found in the middle reaches of the “Sanjiang”. Forest carbon density was the highest in the Jomda County (in northeastern Changdu), and the lowest in Mangkang County (in southeastern Changdu). The distribution pattern showed that the upper reaches of the “Sanjiang” had the higher average carbon density, followed by the southern region of “Sanjiang”, and the middle reaches of “Sanjiang” had the lowest. However, the difference of spatial distribution of carbon density was relatively small (60.55-74.41 t·hm^-2).

Key words: phospholipid fatty acid (PLFA), alpine forest, soil enzyme activity, soil microbial community, simulated warming