| 摘要: |
| 森林土壤是陆地生态系统最大的碳库，提升其有机碳储量与稳定性水平是实现“碳达峰”和“碳中和”目标的重要抓手。目前，我国大面积人工纯林正面临地力衰退、生产力下降与固碳潜力低下等问题，而混交造林作为改善人工林土壤碳汇功能的有效策略，其能否提高土壤有机碳(SOC)稳定性依然存在诸多争议。本文基于SOC形成的前沿理论框架，系统综述混交造林提升SOC储量与稳定性的研究进展。首先，阐明将SOC划分为颗粒态有机碳(POC)与矿物结合态有机碳(MAOC)的科学意义，并引入“碳饱和亏缺”概念，解析制约MAOC累积的主要影响因子。其次，深入剖析混交造林促进SOC累积的核心机制，具体包括：(1)通过生态位互补与选择效应提升林分生产力，从而增加凋落物和根系残体输入总量；(2)通过改善凋落物整体质量、促进凋落物协同分解，进而促使有机碳从凋落物层向矿质土壤迁移；(3)通过优化土壤微生物群落结构，提高土壤微生物碳利用效率，促使微生物将更多的植物来源碳转化为微生物残体碳；(4)通过刺激根系周转、根系分泌物释放与菌根互补，从而促进植物将光合作用碳转移至根际土壤、表层土壤及深层土壤。再次，系统探讨混交造林如何通过调控凋落物与根系性状，以及发挥根系-菌丝-分泌物的协同作用来促进土壤MAOC的形成；在此基础上，进一步分析影响混交林土壤固碳效应的主要因素，包括树种组成、混交模式、林分年龄与立地条件等，并辩证讨论混交模式可能引发的强烈种间竞争及老碳激发分解等潜在负面影响。最后，展望未来的研究方向，指出亟须加强长期定位试验、关注深层土壤碳动态、整合多组学技术与模型模拟，以期为优化区域混交造林模式、提升森林土壤碳汇潜力提供科学依据。 |
| 关键词: 混交造林 土壤有机碳 碳库稳定性 颗粒态有机碳 矿物结合态有机碳 森林经营 微生物碳泵 |
| DOI：10.13656/j.cnki.gxkx.20260708.003 |
| 投稿时间：2026-04-04修订日期：2026-05-13 |
| 基金项目:国家自然科学基金联合基金项目(U24A20576)资助。 |
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| Mechanisms of Enhancing Soil Organic Carbon Pools and Their Stability Through Mixed-Species Afforestation: A Review |
|
LI Dejun1,2, ZHU Zihong1,2
|
| (1.Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha, Hunan, 410125, China;2.Huanjiang Observation and Research Station for Karst Ecosystems, Chinese Academy of Sciences, Hechi, Guangxi, 547100, China) |
| Abstract: |
| Forest soils constitute the largest carbon pool in terrestrial ecosystems.Therefore,enhancing Soil Organic Carbon (SOC) storage and stability in forests is a crucial strategy for achieving the goals of carbon peaking and carbon neutrality.At present,large-scale monoculture plantations in China are facing ecological challenges,including soil fertility degradation,declining productivity,and low carbon sequestration potential.Although mixed-species afforestation is confirmed to effectively improve soil carbon sink potential in plantations,considerable controversy remains regarding whether it can improve the SOC stability.Grounding on the theoretical framework of SOC formation,this study systematically reviews the research progress in enhancing SOC storage and stability through mixed species afforestation.First,this paper elaborates on the significance of distinguishing SOC between Particulate Organic Carbon (POC) and Mineral-Associated Organic Carbon (MAOC),and introduces the concept of carbon saturation deficit to elucidate the main factors constraining MAOC accumulation.Second,this paper delves into the core mechanisms by which mixed-species afforestation increases SOC storage.The specific mechanisms include (1) enhancing stand productivity through niche complementarity and selection effects,thus increasing the input of litter and root residues;(2) improving overall litter quality and promoting synergistic litter decomposition to stimulate the organic carbon transfer from the litter layer to mineral soil;(3) optimizing soil microbial community structure and increasing microbial carbon use efficiency,enabling microbes to convert more plant-derived carbon into microbial necromass carbon;and (4) stimulating root turnover and root exudate release,or forming mycorrhizal complementarity,to assist plants in transferring photosynthetically fixed carbon to rhizosphere,surface,and deep soils.Third,this paper systematically discusses how mixed-species afforestation promotes the formation of MAOC by regulating litter and root traits,as well as through synergistic effects of roots,hyphae,and exudates.On this basis,this paper analyzes the key factors such as tree species composition,mixing patterns,stand age,and site conditions that modulate soil carbon sequestration following mixed-species afforestation and critically assesses the potential negative trade-offs (e.g.,intense interspecific competition and priming-induced decomposition of old carbon) of the mixing-species strategy.Finally,this paper proposes an outlook on future research,highlighting the urgent need for strengthening long-term field experiments,attending to deep soil carbon dynamics,and integrating multi-omics technologies with model simulations.These efforts are expected to provide a scientific basis for optimizing regional mixed-species afforestation models and enhancing the forest soil carbon sink potential. |
| Key words: mixed-species afforestation soil organic carbon carbon pool stability particulate organic carbon mineral-associated organic carbon forest management microbial carbon pump |
