State Key Laboratory of Resources and Environment Information System, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing, 100101, China; University of Chinese Academy of Sciences, Beijing, 100049, China.
University of Chinese Academy of Sciences, Beijing, 100049, China; Key Laboratory of Land Surface Pattern and Simulation, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing, 100101, China.
J Environ Manage. 2021 Dec 15;300:113757. doi: 10.1016/j.jenvman.2021.113757. Epub 2021 Sep 16.
As a prominent part of global and regional terrestrial carbon (C) pools, increases in forest biomass C sinks can be attributed to either forest areal expansion (FAE) or increased biomass C density (IBCD). Accurate estimates of the relative contributions of FAE and IBCD to forest C sequestration can improve our understanding of forest C cycling processes and will help to formulate rational afforestation policies to cope with global warming. In this study, the Continuous Biomass Expansion Factor (CBEF) model and Forest Identity concept were used to map the spatiotemporal variation of the relative contribution of FAE and IBCD to the C sequestration of forest (natural and planted forests) in China and seven regions during the past 40 years. Our results suggest that: (1) total forest biomass C density and stocks of forest increased from 35.41 Mg C ha and 4128.50 Tg C to 43.95 Mg C ha and 7906.23 Tg C in China from 1977 to 2018, respectively; (2) for all forests, the IBCD has been a smaller contributor to C sinks than FAE in China from 1977 to 2018 (33.27 vs. 66.73%); (3) the contribution of FAE to C sinks is greater than that of IBCD in planted forests (63.99 vs. 36.01%), while in natural forests, IBCD has a larger contribution than FAE (57.82 vs. 42.18%) from 1977 to 2018 and the relative contribution of FAE has exceeded IBCD in the last decade; and (4) these patterns varied at the regional level such that the relative contribution of FAE increased for planted forests in most regions but for natural forests, IBCD gradually reached saturation and C stocks declined in northern regions in the last decade. The results from this study suggest that total biomass C sinks will keep increasing because of the increased forest area contributed by afforestation and the relatively young trees in planted forests. This study facilitates a more comprehensive assessment of forest C budgets and improves our understanding of ecological mechanisms of forest biomass carbon stock and dynamics.
作为全球和区域陆地碳（C）库的重要组成部分，森林生物量 C 汇的增加可以归因于森林面积的扩大（FAE）或生物量 C 密度的增加（IBCD）。准确估计 FAE 和 IBCD 对森林 C 封存的相对贡献可以提高我们对森林 C 循环过程的理解，并有助于制定合理的造林政策以应对全球变暖。在这项研究中，连续生物量扩展因子（CBEF）模型和森林身份概念被用于绘制过去 40 年来中国和七个地区森林（天然林和人工林）FAE 和 IBCD 对 C 封存相对贡献的时空变化。我们的结果表明：（1）从 1977 年到 2018 年，中国森林总生物量 C 密度和森林存量分别从 35.41 Mg C ha 和 4128.50Tg C 增加到 43.95 Mg C ha 和 7906.23Tg C；（2）在所有森林中，1977 年至 2018 年，IBCD 对中国森林 C 汇的贡献一直小于 FAE（33.27%比 66.73%）；（3）在人工林中，FAE 对 C 汇的贡献大于 IBCD（63.99%比 36.01%），而在天然林中，1977 年至 2018 年，IBCD 对 C 汇的贡献大于 FAE（57.82%比 42.18%），且在过去十年中，FAE 的相对贡献超过了 IBCD；（4）这些模式在区域水平上有所不同，例如，在大多数地区，人工林的 FAE 相对贡献增加，而在过去十年中，北方地区的天然林 IBCD 逐渐达到饱和，森林 C 储量下降。本研究的结果表明，由于造林增加的森林面积和人工林中相对较年轻的树木，总生物量 C 汇将继续增加。本研究有助于更全面地评估森林 C 预算，并提高我们对森林生物量碳储量和动态的生态机制的理解。
