Extrapolating leaf CO2 exchange to the canopy: A generalized model of forest photosynthesis compared with measurements by eddy correlation
Extrapolating leaf CO2 exchange to the canopy: A generalized model of forest photosynthesis compared with measurements by eddy correlation
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DOI：
10.1007/bf00328606
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发表时间：
1996-04-01
期刊：
影响因子：
2.7
通讯作者：
Goulden, ML
中科院分区：
文献类型：
--
作者：
Aber, JD;Reich, PB;Goulden, ML
在过去的4年中，出现了两个数据集，使整个森林冠层的光合作用模型的定义和验证的准确性和分辨率提高。第一个是温带和热带木本植物氮-光合作用关系的一组扩展数据。第二个是马萨诸塞州彼得舍姆的哈佛森林的一组独特的长期（4年）每日碳平衡测量，通过涡动相关技术收集。一个模型（PnET天），这是直接从这些数据集，并验证。PnET-Day模型使用叶片氮浓度来计算总光合作用和净光合作用的最大瞬时速率，然后将其减少为次优温度、光合有效辐射（PAR）和蒸汽压亏缺（VPD）。预测的每日总光合作用是密切相关的总碳交换在哈佛森林的涡动相关测量。全冠层模型的预测结果明显优于多元线性回归模型。该模型的落叶阔叶林的敏感性分析表明，结果是更敏感的参数相关的最大叶片水平光合速率（A（最大））比那些相关的光，温度，VPD或总叶质量。聚集分析表明，使用月平均气候数据来驱动冠层模型将得到类似的结果，通过平均每日涡动相关测量的总碳交换（GCE）。
Over the last 4 years, two data sets have emerged which allow increased accuracy and resolution in the definition and validation of a photosynthesis model for whole forest canopies. The first is a greatly exp expanded set of data on the nitrogen-photosynthesis relationship for temperate and tropical woody species, The second is a unique set of long-term (4 year) daily carbon balance measurements at the Harvard Forest, Petersham, Massachusetts, collected by the eddy-correlation technique. A model (PnET-Day) is presented which is derived directly from, and validated against, these data sets. The PnET-Day model uses foliar nitrogen concentration to calculate maximum instantaneous rates of gross and net photosynthesis which are then reduced for suboptimal temperature, photosynthetically active radiation (PAR), and vapor pressure deficit (VPD). Predicted daily gross photosynthesis is closely related to gross carbon exchange at the Harvard Forest as determined by eddy correlation measurements. Predictions made by the full canopy model were significantly better than those produced by a multiple linear regression model. Sensitivity analyses for this model for a deciduous broad-leaved forest showed results to be much more sensitive to parameters related to maximum leaf-level photosynthetic rate (A(max)) than to those related to light, temperature, VPD or total foliar mass. Aggregation analyses suggest that using monthly mean climatic data to drive the canopy model will give results similar to those achieved by averaging daily eddy correlation measurements of gross carbon exchange (GCE).