基于森林资源清查数据的林地利用效率变化研究

【目的】定量分析我国重要林区林地利用效率变化差异及对其生态经济的影响,为制定森林资源管理措施提供参考。【方法】从森林资源变动角度,结合森林面积、蓄积量、生物量和碳储量等4个属性,利用1989—2018年森林资源清查数据,从林区和省级两个尺度上量化分析我国南方林区和西南林区的林地利用效率变化。【结果】研究期间,南方林区碳储量增加1.17 Pg,森林面积、蓄积密度、生物量转换比和碳储量的年变化率分别为1.91%、2.07%、0.40%和4.38%;西南林区碳储量增加0.95 Pg,森林面积、蓄积密度、生物量转换比和碳储量的年变化率分别为1.79%、0.07%、-0.05%和1.81%。各省(市、区)森林蓄积量均增加,其中上海、江苏、贵州和西藏林区面积相对贡献最高,而福建和海南林区面积及蓄积密度(即单位面积蓄积)增长速度不均衡将影响后期发展,云南和西藏蓄积密度下降导致蓄积量增长缓慢。各省森林均发挥碳汇作用,南方林区固碳能力优势突出,上海和江苏最为显著,西南林区三省(自治区)林区碳汇均处于缓慢发展水平。【结论】为提高林地利用效率,西南林区应继续提升退耕还林力度,提高补偿标准和年限;对于林龄结构不合理的天然林,应进行可持续经营管理,人为促进更新过熟林以提高其更新能力。南方林区应积极发展造林再造林项目和重点地区速生林工程,发挥人工林生长迅速、在较长时间内维持碳汇能力稳定上升的优势。

Analysis on the forest land use efficiency changes based on forest resource inventory data

【Objective】Quantitative analysis of the difference in forest land use efficiency and its eco-economic impact in important forest regions of China can provide a reference for formulating forest resource management measures. 【Method】From the perspective of changes in forest resources, combined with the four attributes of forest area, volume, biomass, and carbon storage, and using forest inventory data for China from 1989 to 2018, the changes in forest land use efficiency in the southern and southwest forest regions are quantitatively analyzed at the forest area and provincial scales. 【Result】During the study period, carbon storage in the southern forest region increases by 1.17 Pg, and the annual change rates for the forest area, volume density, biomass ratio, carbon storage are 1.91%, 2.07%, 0.40%, and 4.38%, respectively. The carbon storage in the southwest forest region increased by 0.95 Pg, and the annual change rates of these attributes are 1.79%, 0.07%, -0.05%, and 1.81%, respectively. The volume has increased for all the provinces, among which Shanghai, Jiangsu, Guizhou, and Tibet have the highest relative contribution. However, the unbalanced growth rate of forest area and volume density (volume per unit area) in Fujian and Hainan will influence the later development, while the decline in the volume density in Yunnan and Tibet will lead to slow growth in volume. Forests in all provinces play a key role in carbon sequestration, with the advantages of carbon sequestration being more prominent in the southern forest region, and especially in Shanghai and Jiangsu. The carbon sequestration capacity for the three provinces in the southwest forest region is at a relatively slow development level.【Conclusion】To improve forest land use efficiency, the government should increase investment and continue to implement the Grain-to-Green Program, while improving the compensation standard and the time limit. Afforestation and reforestation projects and fast-growing forest projects should continue to be actively developed in key areas, to give full play to the advantages of rapid growth of plantations and a stable increase in the carbon sink capacity over longer time scales. For natural forests with an unsuitable age structure, sustainable management should be undertaken to artificially promote the regeneration ability of over-mature forests to improve the decline in volume density and encourage forestry to maximize its carbon sequestration potential.