权益分类	功能权益	普通用户	{{item.name}}会员
{{category.name}}	{{benefitItem.name}}

Study on carbon cycle in forest ecosystem using stable oxygen isotopic measurement

利用稳定氧同位素测量研究森林生态系统碳循环

基本信息

批准号：
18510019
负责人：
MURAYAMA Shohei
金额：
$ 2.57万
依托单位：
National Institute of Advanced Industrial Science and Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2006
资助国家：
日本
起止时间：
2006 至 2007
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-18510019/
关键词：
stable oxygen isotopic ratio carbon cycle exchange between atmosphere and forest ecosystem hydrological processes isotopic discrimination 大気-森林生態系交換

项目摘要

Systematic measurements of atmospheric CO_2 concentration and its stable oxygen isotopic ratio (δ^<18>O) in and above the forest together with δ^<18>O of CO_2 in soil an, precipitation, soil water, water vapor and leaf water were made in a cool-temperate deciduous forest at Takayama site in central Japan. Using the observed data, temporal variations of δ^<18>O discriminations during photosynthesis and ecosystem respiration were estimated, and possibility of separating these carbon budget components from net ecosystem CO_2 exchange obtained from the eddy covariance flux measurement was examined. δ^<18>O of atmospheric CO_2 showed more complicated diurnal variation than CO_2 concentration, but prominent δ^<18>O increase appeared in the daytime under sunny and dry conditions, reflecting increase of photosynthetic ^<18>O discrimination. Seasonal variation of daytime δ^<18>O of CO_2 above the forest showed scattered but low values in winter and high values in spring. From late spring to early fall, significant year-to-year difference of the variation was seen with low and high values under respective rainy and sunny summer conditions, which may reflect difference of biological and hydrological processes due to that of meteorological conditions associated with the Asian summer monsoon. Comparison with the data at northern mid latitude sites suggested that the rapid decrease of δ^<18>O seen at Takayama in early summer of the rainy summer year is characteristic of the monsoon Asian region. From comparison of the CO^<18>O fluxes associated with photosynthesis and respiration calculated using a simple one-box canopy air model with the variation of the observed δ^<18>O of CO_2, it was found that the model cannot adequately simulate the δ^<18>O variation. The result suggested that analyses of the δ^<18>O data using a multi-layered canopy process model are necessary to precisely separate photosynthetic and respiratory CO_2 fluxes.

对日本中部高山地区寒温性落叶林的大气CO_2浓度及其稳定氧同位素比值（δ^<18>O），以及<18>土壤、降水、土壤水、水汽和叶水中CO_2的δ^ O进行了系统的测定。利用观测资料，估算了<18>光合作用和生态系统呼吸过程中δ^ O判别的时间变化，并探讨了从涡度相关通量测量得到的生态系统CO2净交换量中分离这些碳收支分量的可能性。大气CO_2 δ^<18>O的日变化比CO_2浓度的日变化复杂，但<18>在晴天和干燥条件下，δ^ O的增加主要出现在白天，反映了光合作用对δ^ O的辨别能力增强<18>。林下CO_2日间δ^ O的季节变化<18>表现为分散的冬季低值和春季高值。从春末秋初到春末秋初，夏季多雨和夏季晴时的年际变化差异明显，表现为低值和高值，这可能反映了与亚洲夏季风相关的气象条件差异所导致的生物和水文过程的差异。与北方中纬度地区的资料比较表明，高山地区在<18>多雨的夏季初夏所观察到的δ^ O的快速下降是季风亚洲地区的特征。用<18>一个简单的单箱冠层空气模式计算了与光合作用和呼吸作用有关的CO^O通量，并与观测到的CO_2 δ <18>^O变化进行了比较，发现该模式不能很好地模拟δ <18>^O的变化。结果表明，<18>利用多层冠层过程模式分析δ^ O数据对于精确分离光合和呼吸CO_2通量是必要的。