【目的】根据福建省森林资源清查数据,估算天然乔木林的生物量碳库及其变化,并提出增汇策略,为天然林的固碳能力提升和科学经营管理提供依据。【方法】基于福建省2003—2018年4次森林资源清查数据,采用生物量转换因子连续函数法,结合主要林分组含碳率、根冠比,估算福建省天然乔木林碳储量变化和碳密度。【结果】福建省天然乔木林碳储量由2003年的156.11 Tg增加到2018年的248.68 Tg,年均增长率为3.15%;碳密度由2003年的47.30 Mg/hm²增加到2018年的76.24 Mg/hm²,年均增长1.93 Mg/hm²。天然乔木林碳储量以阔叶类树种(含针阔混交林)占主体,4个清查时期占比均超过70%,最高达86.47%。2003—2018年,天然乔木林幼龄林和中龄林面积占比58.78%~73.76%,碳储量占比50.72%~61.90%,面积和碳储量都以幼、中龄林为主,但占比均呈现明显下降趋势,且呈现碳储量占比明显低于面积占比的特征。天然乔木林碳密度随着林龄的增加呈现明显上升趋势,各林分的碳密度总体上以阔叶类高于针叶类。【结论】福建省天然乔木林碳储量呈较快增长趋势,碳密度不断提高,碳汇能力明显增强,随着天然林保护、生态修复的持续,现阶段以中幼龄林为主的天然乔木林已进入快速增长期,未来固碳潜力巨大。

【Objective】Natural arbor forest biomass carbon pool and its changes were estimated for Fujian Province based on inventory data for forest resources. Strategies for increasing carbon sinks have been put forward, which provided a theoretical basis for the improvement of the carbon sequestration capacity and the scientific management of natural forest.【Method】The carbon storage and the carbon density of the natural arbor forest in Fujian Province were estimated based on four sets of forest inventory data from 2003 to 2018 using the continuous biomass expansion factor method, combined with the carbon fraction and the root shoot ratio of the main forest types.【Result】Results showed that the natural arbor forest carbon storage in Fujian Province increased from 156.11 Tg in 2003 to 248.68 Tg in 2018, with an average annual growth rate of 3.15%. The carbon density increased from 47.30 Mg/hm² in 2003 to 76.24 Mg/hm² in 2018, with an average annual growth rate of 1.93 Mg/hm². The carbon storage of the natural arbor forest was dominated by broad-leaved species including mixed coniferous and broadleaved forest. This accounted for more than 70% of the four forest inventory periods up to 86.47%. From 2003 to 2018, the area of young and middle-age natural arbor forest accounted for 58.78%-73.76%,and the carbon storage accounted for 50.72%-61.90%. The area and the carbon storage were predominantly young and middle-aged forest,but the proportion showed a pronounced downward trend. The proportion of carbon storage was significantly lower than that of the area. The carbon density of the natural arbor forest showed a pronounced upward trend with the increase in forest age. The carbon density of the broadleaved species was higher than that of the coniferous species.【Conclusion】The natural arbor forest carbon storage and the carbon density of Fujian Province show a trend of rapid growth, and the carbon sink capacity markedly enhanced. With the continuous strengthening of natural forest protection and ecological restoration, the dominant young and middle-age forest has entered a fast period for growth. There is considerable potential for natural arbor forest carbon sequestration in the future.