Unraveling differential carbon sequestration pathways among growth, mortality, and recruitment pools in natural larch-birch mixed forests in Northeast China

[Geoengineering News]

https://www.sciencedirect.com/science/article/abs/pii/S0378112725005298

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Authors

Xuesong Mei, Zhaogang Liu, Lingbo Dong

29 July 2025

https://doi.org/10.1016/j.foreco.2025.123021

Highlights

•Climate plays a key role in regulating forest growth (GCS) and recruitment (RCS).

•Topography and stand factors influence forest carbon sequestration dynamics.

•Forest age is the primary factor affecting mortality (MCS).

•Combining stepwise regression and SEM to provide new insights into the response of cold-temperate forests to climate change.

Abstract

Forest carbon sequestration processes are governed by complex interactions among multiple carbon pools. Elucidating the driving mechanisms of these processes is critical for optimizing carbon sequestration potential and mitigating global climate change. In this study, we systematically quantified the relative contributions of topographic, stand structural, soil physiochemical, and climatic factors to carbon sequestration across four functional pools: growth (GCS), recruitment (RCS), mortality (MCS), and total (TCS) carbon sequestration. Through stepwise regression analysis and structural equation modeling, we identified key determinants and their interactive effects on carbon sequestration processes based on 168 natural larch-birch mixed forests in northeast China that collected from the seventh and eighth national forest resources inventories. The results indicated the mean TCS for natural larch-birch forest was 1.56 ± 0.05 Mg·ha-¹ ·yr-¹ , comprising contributions from 52.6 % of GCS, 10.9 % of RCS, and 36.5 % of MCS, respectively. TCS, GCS, and RCS exhibited significant negative correlations with stand age (p < 0.01), whereas MCS showed a positive relationship (p < 0.05). TCS were exerted by topography (β = −0.356, p < 0.01), stand structure (β = 0.007, p < 0.01), and soil conditions (β = 0.197, p < 0.01), with no significant indirect pathways detected. Stand age (β = 0.782, p < 0.001) indirectly influenced TCS through mediation of stand structure. Topography (51.5 % of total influence) and climate (20.6 %) were the dominant drivers of GCS, operating indirectly via effects on soil conditions. RCS was primarily governed by stand characteristics (67.2 % of explained variation), with mean tree height exhibiting strong negative effects (β = −0.710, p < 0.001). MCS variability was largely explained by stand age (p < 0.001), demonstrating a positive relationship where older stands had higher mortality. These findings underscore the critical role of stand structure optimization in maximizing carbon sequestration potential under climate change scenarios.

Source: ScienceDirect