School of Life Sciences, Hebei University, Baoding, China.
School of Ecology and Nature Conservation, Beijing Forestry University, Beijing, China.
Glob Chang Biol. 2024 Jun;30(6):e17386. doi: 10.1111/gcb.17386.
Understanding the mechanisms of soil organic carbon (SOC) sequestration in forests is vital to ecosystem carbon budgeting and helps gain insight in the functioning and sustainable management of world forests. An explicit knowledge of the mechanisms driving global SOC sequestration in forests is still lacking because of the complex interplays between climate, soil, and forest type in influencing SOC pool size and stability. Based on a synthesis of 1179 observations from 292 studies across global forests, we quantified the relative importance of climate, soil property, and forest type on total SOC content and the specific contents of physical (particulate vs. mineral-associated SOC) and chemical (labile vs. recalcitrant SOC) pools in upper 10 cm mineral soils, as well as SOC stock in the O horizons. The variability in the total SOC content of the mineral soils was better explained by climate (47%-60%) and soil factors (26%-50%) than by NPP (10%-20%). The total SOC content and contents of particulate (POC) and recalcitrant SOC (ROC) of the mineral soils all decreased with increasing mean annual temperature because SOC decomposition overrides the C replenishment under warmer climate. The content of mineral-associated organic carbon (MAOC) was influenced by temperature, which directly affected microbial activity. Additionally, the presence of clay and iron oxides physically protected SOC by forming MAOC. The SOC stock in the O horizons was larger in the temperate zone and Mediterranean regions than in the boreal and sub/tropical zones. Mixed forests had 64% larger SOC pools than either broadleaf or coniferous forests, because of (i) higher productivity and (ii) litter input from different tree species resulting in diversification of molecular composition of SOC and microbial community. While climate, soil, and forest type jointly determine the formation and stability of SOC, climate predominantly controls the global patterns of SOC pools in forest ecosystems.
了解森林土壤有机碳（SOC）固存的机制对于生态系统碳预算至关重要，有助于深入了解世界森林的功能和可持续管理。由于气候、土壤和森林类型在影响 SOC 库大小和稳定性方面的复杂相互作用，全球森林 SOC 固存的机制仍不清楚。基于对全球森林 292 项研究的 1179 个观测结果的综合分析，我们量化了气候、土壤特性和森林类型对上层 10cm 矿质土壤中总 SOC 含量以及物理（颗粒与矿物结合 SOC 相比）和化学（活性与惰性 SOC 相比）SOC 库的特定含量以及 O 层 SOC 储量的相对重要性。矿质土壤总 SOC 含量的变异性主要受气候（47%-60%）和土壤因素（26%-50%）的影响，其次是 NPP（10%-20%）。由于温暖气候下 SOC 分解超过 C 补充，矿质土壤中总 SOC 含量以及颗粒态（POC）和惰性 SOC（ROC）含量均随年平均温度升高而降低。矿物结合有机碳（MAOC）的含量受温度影响，温度直接影响微生物活性。此外，粘土和氧化铁的存在通过形成 MAOC 来物理保护 SOC。O 层的 SOC 储量在温带和地中海地区比在北方和亚热带地区更大。由于（i）生产力更高，（ii）不同树种的凋落物输入导致 SOC 和微生物群落的分子组成多样化，因此混交林的 SOC 库比阔叶林或针叶林大 64%。虽然气候、土壤和森林类型共同决定 SOC 的形成和稳定性，但气候主要控制森林生态系统中 SOC 库的全球格局。
