四川省及重庆地区森林植被碳储量动态

四川省及重庆市地区森林植被是我国第二大林区-西南林区的主体,位于"世界第三极"--青藏高原东缘.在建立森林乔木层生物量与蓄积量回归模型的基础上,按林分类型测定含碳量,结合四川4次森林资源清查数据,估算了不同时段的碳储量.各林分类型含碳量在46.75%～54.89%之间,平均含碳量为51.09%,针叶林平均含碳量(52.82%)大于阔叶林(49.37%);四川森林植被碳储量从1988年的383.04TgC增加到2003年的523.57TgC,增加了140.53TgC,年均增长率2.11%,比全国年均增长率高出0.22%,表明四川森林植被是CO2的一个汇.4次调查的森林植被平均碳密度分别为38.93、38.68、39.17、41.66MgC/hm2,呈现增加趋势,表明森林植被的碳汇功能不断加强;成熟林碳储量占同期的64.15%、63.89%、65.33%、60.82%,但所占比重呈下降的趋势,幼中林碳储量的比重不断上升,表明森林植被的碳吸存潜力大;森林植被碳储量主要分布在天然林中,占同期碳储量的90%以上,但人工林的碳储能力正在逐步提高,人工林碳年均增长率(7.17%)明显大于天然林(1.83%),表明人工林将在研究区域森林植被碳汇功能中扮演重要的角色.研究区森林植被碳储量占同期全国碳储量的比例呈增加趋势,可见,研究区森林植被在全国森林碳汇中具有重要的作用和地位.

Dynamics on forest carbon stock in Sichuan Province and Chongqing City

Forest in Sichuan (including Chongqing) locate in the eastern of Tibet Plateau honored by the third pole in the world. As a principal part of SW forest region, the second largest forest region in China, the forest carbon stock plays an important role in global carbon cycle, implying that it is important for forest carbon stock evaluation to understand the role of the forest in mitigating climate change. Therefore, carbon stocks in Sichuan (including Chongqing) forest at different phases were evaluated to understand the contribution of Sichuan forest to mitigate climate change, employing the methods of establishing the model of forest biomass and volume, measuring carbon content in different stands and integrating four provincial forest inventory data in Sichuan (including Chongqing). Mean carbon content of the studied forest stands was 51.09%, ranging from 46.75% to 54.89% ,and depending on the forest stands. On average, carbon content was 52.82% in the coniferous forest, which was significantly higher than that in the broadleaved forest (49.37%). Forest carbon stock in Sichuan increased 140.53 Tg C from 383.04 TgC in 1998 to 523.57 TgC in 2003 and by 2.11% annually during the study period, which was more 0.22% than that of the mean increment in China, implying that Sichuan (including Chongqing) forest is carbon sink in atmospheric carbon dioxide, and contributes to climate change mitigation. Correspondingly, average carbon density in the forest was 38.93, 38.68, 39.17 MgC/hm2, and 41.66 MgC/hm2, respectively, and showed the increasing trend during the period of four forestry inventories, implying that the potential of carbon sink in Sichuan (including Chongqing) forest was increasing. Carbon stock in mature forest showed the declining trend in the study period, which accounted for 64.15%, 63.89%, 65.33%, and 60.82% of the total in the corresponding phase, respectively, while that in young and middle-aged forest showed the opposite, showing that the study forest has a strong potential of carbon sequestration. Meanwhile, the potential of carbon sequestration in the plantation increased continuously although natural forest stored carbon more than 90% for the same stage, resulting that annual increment of carbon stock in the plantation was 7.17% in comparison with 1.83% in natural forest. The results showed that man-made forest played an important role in enhancing forest carbon sequestration in the study region. Furthermore, the results also showed that Sichuan the study forest played an important and irreplaceable role in enhancing national forest carbon sequestration due to higher carbon sequestration in the forest in comparison with national level.