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.

在森林内外，在森林中及以上的大气CO_2浓度及其稳定的氧同位素比（δ^<18> o）以及δ^18> O的Δ^^18> o在土壤中，降水，土壤水，水蒸气和叶片水在日本中部的塔基亚山山上的凉爽的森林中制成。使用观察到的数据，估算了光合作用和生态系统呼吸过程中δ^<18> o的暂时变化，并可能检查了将这些碳预算组件与从涡流协调量的净生态系统CO_2交换中分离出来的。大气CO_2的δ^<18> O比CO_2浓度显示出更为复杂的差异变化，但在阳光明媚和干燥的条件下，明显的δ^<18> o出现在白天出现，这反映了光合作用^<18> o歧视的增加。森林上方的co_2白天δ^<18> o的季节性变化显示为散落但冬季较低的值和春季高值。从春末到初秋，在相对雨和阳光明媚的夏季条件下，观察到差异的显着差异，这可能反映出由于与亚洲夏季季风相关的气象条件而导致的生物和氢过程的差异。与北部纬度部位的数据进行比较，表明Δ^<18> o的迅速下降是雨夏季初的高山，是季风亚洲地区的特征。从与光合作用和呼吸相关的CO^<18> o的比较，使用简单的单盒冠层空气模型计算出具有CO_2的δ^<18> O的变化，因此发现该模型无法充分模拟δ^<18> o变异。结果表明，使用多层顶盖工艺模型对数据进行分析对于精确分离光合作用和呼吸CO_2通量是必要的。