基于立地条件和林分特征的区域尺度森林固碳速率和碳汇潜力

The role of carbon sequestration and carbon sinks in forests is particularly important in the context of global climate change. However, there is a great deal of uncertainty in the measurement and estimation of forest carbon sequestration and carbon sink potential at the regional scale. The research would take Guangdong province as the case at regional scale, five-period data grouped by forest types from Chinese national forest inventory (CNFI), were used to calculate above- and below-ground biomass of arbor forests at stand level. Considering the stand density, the method of estimating parameters for the forest biomass growth model would be studies by means of differential equations. At the regional scale, the classified forest biomass growth equation was established by assuming that a specific plot has an invariant biomass growth classification in five periods. Annual growth biomass was calculated by deducting the derivative of the equation by age, and then the carbon sequestration rate at stand level was obtained. Filtering the climate, topography, soil and other site factors and stand characteristics which had a significant effect on the carbon sequestration rate at the reference age, the linear or non-linear carbon sequestration model comprising either main effect or the interaction effect was established to quantify the contribution and the guide of each factor to carbon sequestration rate. Taking the existing conditions as a benchmark, a variety of scenarios have been set up to predict the potential of forest carbon sink in the future 20-30 years at the regional scale, to distinguish the impact of management measures and natural factors on forest carbon sink and to quantify the contribution of management regimes to increasing carbon sink. The research would provide theoretical support and technical means for the scientific measurement, accurate reporting, strict certification and effective verification of carbon sequestration rate and carbon sequestration potential at the regional scale.

森林的固碳和增汇作用在全球气候变化的背景下显得尤为重要，然而，区域尺度森林固碳速率和碳汇潜力的计量和估算，存在极大的不确定性。本项目以广东省为实验区，利用五期连清资料，分森林类型，以乔木林地上和生地下生物量为对象，考虑林分密度，采用生长模型的差分方程，研究林分生物量生长模型参数导出形式。区域尺度上，约束同一样地多期数据具有同一生长等级，建立分级林分生物量生长模型，按年龄求导，获得生物量连年生长量，进而获得固碳速率。采用基准年龄时的固碳速率，筛选有显著影响的气候、地形、土壤等立地因子和林分特征，建立主效应或包含交互效应的固碳速率模型，量化各个因子对固碳速率的贡献和影响方向。以现有情景为基准，设定多种情景，预测未来20-30年区域森林的碳汇潜力，区分经营和自然对森林碳汇的影响，为区域尺度森林固碳速率、碳汇潜力的科学计量、精确报告、严格认证与有效核查提供方法学上的理论支撑和技术手段。

基于广东省樟树、木荷和枫香3种常绿阔叶树的实测生物量数据，分析了影响树密度和木材密度的因子，研究了生物量可加模型的误差结构，比较了两种生物量相容性模型的拟合效应和不同组分的解释变量；利用全球广泛分布的落叶松生物量模型，分析了模型形式和地域对生物量模型应用的影响；基于多期保留木胸径实测数据，深入研究了林分年龄的确定方法，建立广东省9个树种含参数分级的林分蓄积量、生物量和碳储量生长模型；基于实测的土壤数据和近30年广东全省的实测气象数据，研究了区域尺度上土壤因子和树种之间的关系，分析了影响不同树种固碳速率地形因子、土壤因子、气候因子等非生物环境因子和林分特征，明确了森林固碳能力的环境驱动力；在不同气候情景下，预测未来20-30年区域尺度上不同树种碳汇潜力和固碳速率。项目提出的基于时间序列的胸径数据确定林分年龄的方法，为全国分省分树种拟合和建立天然碳储量生长模型提供了基础，已经应用于中国工程院《森林、草地、湿地、荒漠等碳储、碳汇与碳利用战略研究报告》和国家林业和草原局重点课题《林草碳中和愿景实现目标战略研究》等，为国家双碳目标的落实和量化在碳中和愿景实现中的林业贡献提供了基础支撑和数据支持，具有广泛的应用前景。项目发表论文17篇，其中SCI收录3篇；培养研究生4名；登记软件著作权2项；参加学术交流8人次。