College of Soil and Water Conservation, Beijing Forestry University, Beijing, PR, China.
School of Water Conservancy and Environment, University of Jinan, Jinan, PR, China.
PLoS One. 2021 May 3;16(5):e0250073. doi: 10.1371/journal.pone.0250073. eCollection 2021.
According to the forest resources inventory data for different periods and the latest estimation parameters of forest carbon reserves in China, the carbon reserves and carbon density of forest biomass in the Tibet Autonomous Region from 1999 to 2019 were estimated using the IPCC international carbon reserves estimation model. The results showed that, during the past 20 years, the forest area, forest stock, and biomass carbon storage in Tibet have been steadily increasing, with an average annual increase of 1.85×104 hm2, 0.033×107 m3, and 0.22×107 t, respectively. Influenced by geographical conditions and the natural environment, the forest area and biomass carbon storage gradually increased from the northwest to the southeast, particularly in Linzhi and Changdu, where there are many primitive forests, which serve as important carbon sinks in Tibet. In terms of the composition of tree species, coniferous forests are dominant in Tibet, particularly those containing Abies fabri, Picea asperata, and Pinus densata, which comprise approximately 45% of the total forest area in Tibet. The ecological location of Tibet has resulted in the area being dominated by shelter forest, comprising 68.76% of the total area, 64.72% of the total forest stock, and 66.34% of the total biomass carbon reserves. The biomass carbon storage was observed to first increase and then decrease with increasing forest age, which is primarily caused by tree growth characteristics. In over-mature forests, trees' photosynthesis decreases along with their accumulation of organic matter, and the trees can die. In addition, this study also observed that the proportion of mature and over-mature forest in Tibet is excessively large, which is not conducive to the sustainable development of forestry in the region. This problem should be addressed in future management and utilization activities.
根据不同时期的森林资源清查数据和中国最新的森林碳储量估算参数，利用 IPCC 国际碳储量估算模型，估算了 1999 年至 2019 年西藏自治区森林生物量碳储量和碳密度。结果表明，过去 20 年，西藏森林面积、森林蓄积和生物量碳储量稳步增加，平均每年分别增加 1.85×104 hm2、0.033×107 m3 和 0.22×107 t。受地理条件和自然环境的影响，森林面积和生物量碳储量自西北向东南逐渐增加，特别是林芝和昌都地区原始森林较多，是西藏重要的碳汇。从树种组成看，西藏以针叶林为主，其中含冷杉、云杉和云南松的森林面积约占西藏森林总面积的 45%。西藏的生态区位导致其以防护林为主，占总面积的 68.76%、总蓄积的 64.72%和总生物量碳储量的 66.34%。生物量碳储量随林龄增加呈现先增加后减少的趋势，这主要是由于树木生长特性所致。在过熟林分中，树木光合作用随着有机质的积累而降低，树木可能会死亡。此外，本研究还观察到西藏成熟和过熟林分比例过大，不利于该地区林业的可持续发展。在未来的管理和利用活动中，应解决这一问题。
