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研究利用基于冠层辐射传输与植物生理过程的MAESTRA模型,结合中国东部鼎湖山、千烟洲及长白山3个典型森林生态系统的CO2通量观测数据,对光合有效辐射(Photosynthetically Active Radiation,PAR)总量及其散射辐射比例变化影响下生态系统总初级生产力(Gross Primary Productivity,GPP)的变化进行了模拟与敏感性分析,从而探讨这两者的变化对森林生态系统GPP的综合影响。研究结果表明:PAR总量变化对GPP的影响程度由PAR总量变化幅度以及GPP对PAR总量变化的敏感程度所决定,较低的PAR总量与较高的温度条件下GPP对PAR总量变化较敏感;散射辐射比例增大可以提高森林冠层对入射PAR的吸收和利用效率,其对GPP的影响程度由散射辐射量的变化以及散射辐射与直射辐射在吸收与利用效率上的差别所决定,较高温度与叶面积条件下该差别较大;PAR总量与散射辐射比例共同变化对GPP的综合影响取决于上述两个过程的抵消结果,入射PAR较强时两者抵消作用通常更明显,在全年总量上,散射辐射比例变化对GPP的影响能抵消PAR总量变化影响的1/3~1/2。
Using the MAESTRA model based on canopy radiation transmission and plant physiological processes, combined with CO2 fluxes from three typical forest ecosystems in Dinghushan, Qianyanzhou and Changbai Mountains in eastern China, the photosynthetically active radiation (PAR) (GPP) in the ecosystem under the influence of the total amount and the proportion of the scattered radiation, the simulation and sensitivity analysis of the changes of the Gross Primary Productivity (GPP) of the ecosystem were carried out to investigate the combined effects of the changes of the two on the GPP of the forest ecosystem. The results showed that the influence of the change of total amount of PAR on GPP was determined by the change of total amount of PAR and the sensitivity of GPP to the change of total amount of PAR. The lower total PAR and the higher total temperature Which is sensitive to the changes of the PAR. The increase of the proportion of scattered radiation can improve the absorption and utilization efficiency of PAR in the canopy. The degree of influence on the GPP is determined by the change of the amount of scattered radiation and the difference of absorption and utilization efficiency between the scattered radiation and the direct radiation The difference between the total amount of PAR and the proportion of scattered radiation on GPP depends on the offsetting results of the above two processes. When the incident PAR is strong, the offsetting effect between the two is usually more Obviously, in the whole year, the influence of the change of the proportion of scattered radiation on GPP can offset the influence of the change of the total amount of PAR by 1/3 ~ 1/2.