Characteristics of CO2 fluxes in cool-temperate coniferous and deciduous broadleaf forests in Japan
Characteristics of CO2 fluxes in cool-temperate coniferous and deciduous broadleaf forests in Japan
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发表时间：
2005
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通讯作者：
Y. Ohtani;N. Saigusa;S. Yamamoto;Y. Mizoguchi;Tsutomu Watanabe;Y. Yasuda;S. Murayama
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作者：
Y. Ohtani;N. Saigusa;S. Yamamoto;Y. Mizoguchi;Tsutomu Watanabe;Y. Yasuda;S. Murayama
在日本富士吉田和高山地区对针叶林和阔叶林进行了长期二氧化碳通量监测。所观测的这两种森林分别是日本寒温带自然再生的次生针叶林和阔叶落叶林的代表。在本报告中，我们通过涡度相关法比较了两个地区的生态系统净生产力，并分析了与森林类型相关的影响生态系统净生产力季节和年际变化的气候因素。观测到的生态系统净生产力表明，高山地区的最大生态系统净生产力约为富士吉田地区的1.5倍，尽管富士吉田地区的生长季约为高山地区的2倍长。富士吉田地区每月的生态系统净生产力在整个季节中年际变化较大，但在高山地区这种变化仅出现在4月至10月。不同森林类型每月生态系统净生产力年际变化的差异可解释如下：针叶林全年都保持着树冠针叶，也就是说，如果气候条件有利，森林随时准备进行同化作用，并且会持续受到太阳辐射（Sd）和气温（Ta）变化的影响。相比之下，阔叶落叶林会经历展叶和落叶过程，因此，受气候变化影响的时期仅限于生长季。呼吸作用比同化作用相对更稳定，因为夏季气温在各年间表现相似，而冬季森林被雪覆盖时气温的年际变化较大。因此，在寒温带针叶林中，太阳辐射和气温的季节变化所引起的同化作用和呼吸作用的平衡是一个重要因素，而在寒温带阔叶落叶林中，太阳辐射和生长季的时长是影响年生态系统净生产力的重要因素。
(73)-(80 Long-terra CΟ 2 flux monitoring in coniferous and deciduous forests was conducted in Fujiyoshida and Takayama sites, Japan. Both forests observed are representatives of naturally regenerated secondary coniferous and broadleaved deciduous forests in cool-temperate regions of Japan. In this report, we compared net ecosystem production in both sites by eddy regions of method, and analyzed the climatic factors that affect the seasonal and inter-annual changes in NEP in relation to forest type. The observed NEP showed that the maximum NEP was about 1.5 times larger in the Takayama site, although the growing period was about 2 times longer in the Fujiyoshida site. The monthly NEP in the Fujiyoshida site had large inter-annual variation throughout the season, but the variation was only appeared from April to October in the Takayama site. The difference in the inter-annual variation in monthly NEP between forest types might be explained as follows. The coniferous forest maintains canopy needles throughout the year, that is, the forest is ready to assimilate if climatic conditions are favorable, and can be continuously affected by changes in Sd and Ta. In contrast, the deciduous broadleaved forest experiences leaf-expansion and leaf-fall events, therefore, the period affected by climatic changes is limited only to the growing season. Respiration is relatively more consistent than assimilation, because the Ta behaves similarly among years in summer, and the forests are snow covered in winter when the inter-annual variation of Ta becomes large. Consequently, in the cool-temperate coniferous forest, the balance of assimilation and respiration induced by seasonal changes in solar radiation and air temperature is an important factor, while in the cool-temperate deciduous broadleaved forest, solar radiation and the duration of the growing season are important factors with regards to annual NEP.