中国主要树种人工乔木林碳储量测算及固碳潜力分析

【目的】森林碳储量在陆地生态系统碳库中占主体地位,通过确定人工乔木林碳密度和植被固碳增值碳储量,预测人工乔木林碳汇潜力,为改善人工乔木林的林龄和树种结构、提高森林可持续经营水平,进而为提高人工乔木林单位面积蓄积量提供科学依据,助力我国实现增汇减排的目标。【方法】比较分析我国第8次(2009—2013)和第9次(2014—2018年)森林资源清查中各优势树种人工林的面积和蓄积量数据,采用联合国政府间气候变化专门委员会(IPCC)材积源-生物量法(volume-biomass methods)分别估算并对比我国6种主要树种人工乔木林的碳储量和碳密度,分析人工乔木林碳储量和碳密度在两次森林资源清查期间增值部分的碳贡献率,综合评价我国不同林龄结构人工乔木林的固碳功能;采用拟合的单位面积蓄积-林龄的Logistic回归生长方程,结合IPCC材积源-生物量法,预测不同龄级各优势树种的蓄积量,估算我国现有人工乔木林未来15年及至2035年的碳汇增值潜力。【结果】两次森林资源清查期间,我国主要人工乔木林总碳储量增加了498.81 Tg,年均增加量99.76 Tg。第9次资源清查结束时,6个主要树种不同林龄(组)人工乔木林的碳储量由大到小依次为过熟林(439.19 Tg)>成熟林(426.43 Tg)>近熟林(359.75 Tg)>中龄林(292.34 Tg)>幼龄林(105.15 Tg),分别占人工乔木林总碳储量的27.07%、26.28%、22.17%、18.02%和6.47%;不同龄组的碳密度从小到大依次为过熟林(59.17 Mg/hm²)<幼龄林(169.12 Mg/hm²)<成熟林(178.13 Mg/hm²)<近熟林(190.38 Mg/hm²)<中龄林(348.09 Mg/hm²)。到2035年,我国主要树种人工乔木林碳储量和平均碳密度将分别达到1 716.27 Tg和36.51 Mg/hm²,与2015年相比分别增加92.92%和93.17%。【结论】两次森林资源清算结果相比,6种主要树种人工乔木林的碳储量均有显著增加,随着林分的不断成熟,碳储量呈现出线性正向增加的趋势,而碳密度受蓄积量与面积比的影响其增幅各不相同;至2035年人工乔木林碳储量约占乔木林总碳储量的20%,可以预见中国人工乔木林碳储量有很大的增加潜力。

The carbon storage calaulation and carbon sequestration potential analysis of the main artificial arboreal forest in China

【Objective】Carbon from the forest plays a dominant role in contributing the development to terrestrial ecosystem. Therefore, the purpose of this study is to predict the carbon sink potential of artificial trees by determining their carbon density and value-added carbon storage potential. The results of the study can further improve the structure of the artificial main forest age groups, improve the sustainable management levels of the forest, provide scientific basis for increasing the artificial tree forest unit area, and achieve the goal of increasing the amount of foreign exchange in China.【Method】This study applied the data of area and volume of the dominate tree species in China. The data are all from the 8th (2009-2013) and the 9th (2014-2018) national forest inventory data of China. Moreover, adopted the IPCC volume-biomass method to calculate the carbon storage and carbon density of the six main artificial arboreal forest. Meanwhile, the changing patterns and age group structure characteristics of the carbon storage and density of artificial arboreal forests in China were also analyzed between the two inventories. The aim of this step was to comprehensively analyze and evaluate China's artificial forest under age structures of carbon sequestration function; furthermore, the fitted unit area accumulation-forest-age logistic regression growth equation was applied and the IPCC volume-biomass methods were combined to calculate the accumulation of different ages of each dominant tree species after decades. The purpose was to estimate the data of carbon storage and carbon density of China's existing artificial arboreal forest in future stages.【Result】During the two inventory periods, the total carbon storage of the main artificial forest increased by 498.81 Tg, with an average annual increase of 99.76 Tg. The carbon storage from the highest to the lowest forest age groups in China was in the following order: over-matured forests (439.19 Tg) > mature forests (426.43 Tg) > near-mature forests (359.75 Tg) > middle-aged forests (292.34 Tg) > young forests (105.15 Tg). Carbon density from the lowest to the highest age groups in China were in the following order: over-matured forests (59.17 Mg/hm²) < young forests (169.12 Mg/hm²) < mature forests (178.13 Mg/hm²) < near-mature forests (190.38 Mg/hm²) < middle age forests (348.09 Mg/hm²). With regard to the future carbon sequestration capacity of artificial forests in China, the analysis results predict that the carbon storage and density of artificial arboreal forests based on current data will increase to 1 716.27 Tg and 36.51 Mg/hm², with an increase of 92.92% and 93.17%, respectively, compared with the values in 2015.【Conclusion】The carbon storage of the six main artificial forest increased significantly between the two inventories. Carbon storage shows a linear positive increase trend, while carbon density does not show a linear increase due to the effect of accumulation of the area and the volume. Moreover, by the year of 2035, the carbon storage of artificial forest will account for about 20% of the total carbon storage, of which the area of young-aged and middle-aged trees will account for 64.66% of the total area of trees in China, and it can be predicted that the carbon storage of main artificial arboreal forest will have great potential for increase.