植物组成多样性对东北地区森林碳汇功能影响及其形成机制

Proper species configuration for co-enhancement of carbon sink and biodiversity conservation is the key for forest conservation and management, and the core base is an exact understanding their coupling mechanism. We choose the typical forests in NE China forest belt at Daxingan and Xiaoxingan Mts. as research sites in this project, and large scale survey and long-term fixed-site measurements were used to determine total forest biomass C, annual C fixation rate and its compositional distribution, soil C storage, sequestration rate, distribution in vertical profile and stability differences, for testifying the hypothesis of key species effect, original status-effect and niche-compensation effect, and finally find the patterns of influences from biodiversity, structure on biomass and soil C sequestration features; Combing laboratory measurement and field control experiment to testify the field observation above-mentioned, then we want to analyze the coupling associations between greenhouse gas exchange characteristics and tree species richness, and explore the possibility for including greenhouse gas into forest carbon sink evaluations; As a further step, the soil carbon sequestration microscale processes related with C efflux traits, returning-soil materials diversity and soil colloids surface physiochemical images were determined with supporting techniques of infra-red spectrum, nuclear magnetic resonance, x-ray diffraction and atomic force microscope. In this control experiment, we will also focus on the differences of aboveground-transported new carbohydrates and stored carbohydrates in debris, coupling patterns of SOM-microbes-minerals, and aggregates-colloids micro-images, for clarifying the complex relations of soil C efflux-influx features and returning SOM diversity. In the whole project, the coupling mechanism were analyzed by regression analysis, Pearson correlation analysis and multivariate analysis of covariance. After finding which factors in tree composition traits are most related with biomass or soil carbon sequestration traits, decoupling the possible way of the driving mechanism were done by analysis of redundancy, principle component, then structural equation models among these driving parameters and carbon efflux-influx traits. We expect that the coupling-decoupling mechanism from viewpoint of above-belowground carbon sink interactions, species and functional form diversity in this study, will theoretically supports the future practices of multifunctional ecological services provision from local natural and planted forests, particularly co-enhancement of carbon sequestration and biodiversity conservation.

准确理解物种组成、林分结构与碳截获的耦合关系及内在机理是协同提升碳汇与多样性保护的核心。作为世界最大造林国家，我国森林建设和保护急需相关数据支撑。本研究以东北森林带核心区域为对象，野外调查与长期定位相结合，确定生物量碳储量、分布特征及累积速率，量化土壤碳储量、累积速率及其垂直分布与稳定性差异，验证关键种效应、初始状态和生态位补偿等假说，最终明确种类组成多样性对森林生物量碳、土壤碳汇的影响方式。结合室内分析与野外控制实验，验证野外发现的基础上，重点解析温室气体排放特征与物种组成的耦合-解耦合关系，探索相关规律融入森林碳汇功能评价的可能性；进一步应用原子力显微镜、红外光谱、X射线衍射及核磁共振等技术，探究团聚体-胶体-土壤有机物化学显微过程，明确物种组成影响土壤碳汇稳定的机制。上述从生物量碳、土壤碳和温室气体等多角度确定的多样性-林分碳汇耦合机制能够支撑我国森林碳汇提升与生物多样性的协同保护。

东北森林是我国最大的国有林区，其生态系统碳汇功能被认为对碳中和目标实现至关重要。本研究建立了9个长期固定大样地，合计面积23.96 ha，形成了植物多样性-森林碳储量耦合关系东北样带。通过新调查与整理前期研究，形成了涵盖乔灌草+种类和树木大小+xy坐标的东北森林野外清查样地数据库（2342块30m*30m的样地）。发现了东北地区针叶林的生物量碳储量、耐分解稳定性显著高于阔叶林25%和43%，但环境稳定较阔叶林低8%。同期林业普查碳储量数据可能低估林分生物量碳密度35%。与历史数据相比，东北地区森林乔木高度均降低数米，重要林下资源植物减少明显。发现了地上树木多样性提升土壤碳汇功能稳定性，可能是通过团聚体稳定提升实现的，这一过程与GRSP促进大团聚体形成有关。人工森林可增加土壤有机碳累积，也导致其温度敏感性降低、碳稳定性增强15%。高树种丰富度导致SOC、真菌结合碳TG、异养呼吸和N2O释放增加16-127%；这种提升受糖苷水解酶、多糖裂解酶、碳水化合物酯酶、糖基转移酶、辅助酶类和碳水化合物结合模块共同调节。基于Maxent模型并与未来气候变化场景分析发现，未来气候情景下，东北森林面积增加，草地和农田面积减小，城市面积先扩张，2025年−2100年的植物多样性较之当前提升7%–11%，生物量碳将提升9%；土壤碳氮储量较之当前各自提升5%。未来造林及林分经营应该充分考虑气候变化与碳汇功能的影响。超额完成量化可考核指标：在2018年-2023年项目执行期间，共发表42篇学术论文，包括SCI论文 29篇(中科院一区6篇；二区12篇），中文核心期刊13篇。第一标注：25篇。科学出版社专著1部，参编Springer专著1部2章节、CABI专著1部1章节。获得教育部自然科学二等奖1项（排名第一）、国家林业局梁希奖1项（排名第一）、吉林省自然科学一等奖1项（第二）。相关结果为东北地区的森林管理提供了基础数据，建议深入开展林分树种组成变化的长期生态学意义与生态风险管控研究，助力国家双碳目标实现。