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太阳辐射是植被进行光合作用的重要驱动因子,影响着森林生态系统的净CO2吸收。本研究基于千烟洲亚热带人工针叶林30 min的通量和常规气象数据,以晴空指数为指标,分析了2003—2010年太阳辐射变化对该森林生态系统净CO2交换(NEE)的影响。结果表明:在晴空指数为0.4~0.6的中等辐射条件下NEE达到最大;与晴朗天空的强太阳辐射相比,中等辐射条件下散射辐射增加、气温以及饱和水汽压差的下降是NEE增加的原因;晴空指数在0.4~0.5和0.5~0.6的NEE显著大于晴空指数在0.7~0.8的NEE;该地晴空指数在0.6~0.7和0~0.1出现的频率较大,表明该地经常出现的天空状况以及对应的太阳辐射强度不是提高该生态系统净CO2吸收的最适条件。
Solar radiation is an important driver of photosynthesis in vegetation and affects the net CO2 absorption of forest ecosystems. Based on the 30-minute flux and conventional meteorological data of the subtropical artificial coniferous forests in Qianyanzhou, the effects of solar radiation changes during 2003-2010 on the net CO2 exchange (NEE) of the forest ecosystem were analyzed based on the clear sky index. The results show that NEE reaches the maximum under moderate radiation with a clear sky index of 0.4-0.6. Compared with strong solar radiation in sunny sky, the scattering radiation increases under moderate radiation, and the decrease of temperature and saturated vapor pressure difference is the reason for the increase of NEE . The NEE with clear sky index of 0.4-0.5 and 0.5-0.6 is significantly larger than NEE with clear sky index of 0.7-0.8. The frequent occurrence of the clear sky index at 0.6-0.7 and 0-0.1 indicates that the frequent sky condition And the corresponding intensity of solar radiation is not the optimum condition for increasing the net CO2 absorption of the ecosystem.