整合生态系统通量观测与植物性状的中国东北样带年总初级生产力时空变异机制研究

分析年总初级生产力（AGPP）的时空变异是评估区域碳汇及生产力的基础，尚缺乏生物学机制的认知，植物性状为AGPP认知提供了生物学证据。基于中国东北样带4个典型生态系统的长期通量观测数据，本研究首先将AGPP分解为碳吸收时间、最大碳吸收速率（GPPmax）及常数，进而从生物物理学的视角将GPPmax分解为年冠层最大导度（AGcref）、年生态系统细胞内外CO2浓度比（ACi/Ca）等组分。结合群落结构和叶片性状调查结果，量化AGcref与植物群落气孔面积指数、ACi/Ca与植物群落13C判别值的对应关系。基于4个生态系统的通量数据，探讨GPPmax空间变异规律，阐明AGPP空间变异的生物学机制。基于各生态系统长期观测结果，分析GPPmax的时间变异规律，阐明AGPP时间变异的生物学机制及区域差异。揭示AGPP时间变异和空间变异机制的差异，增进AGPP时空变异的生物学认知。

Analyzing the spatiotemporal variations of annual gross primary productivity (AGPP) would set a basis for assessing the regional carbon sink and productivity, which lacked a biological mechanism understanding. Plant traits provide a biological evidence for AGPP spatiotemporal variations. Based on long-term network eddy covariance measurements in 4 typical ecosystems of Northeast China Transect, this study separated AGPP into carbon uptake period, the maximal capacity of CO2 uptake (GPPmax), and a constant. Then GPPmax were divided into its components like the annual canopy maximum conductance (AGcref) and annual ecosystem ratio between the intercellular and the ambient CO2 concentration (ACi/Ca) from the biophysical viewpoint. After integrating community structure and leaf trait surveys, the correspondence between AGcref and community stomatal area fraction, and that between ACi/Ca and community 13C discrimination, were quantified. Based on flux measurements in 4 ecosystems, the spatial variability of GPPmax was analyzed to reveal the biological mechanism underlying AGPP spatial variation. Then long term measurements of each ecosystem were employed to analyze the temporal variations of GPPmax. Then the biological mechanism underlying the AGPP temporal variation and its regional difference were clarified. The difference between mechanisms underlying spatial and temporal variations of AGPP was also investigated to improve the biological understanding on AGPP spatiotemporal variations.