Spatial and temporal variability in methane emissions from tree stems of Fraxinus mandshurica in a cool-temperate floodplain forest
Spatial and temporal variability in methane emissions from tree stems of Fraxinus mandshurica in a cool-temperate floodplain forest
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DOI：
10.1007/s10533-015-0070-y
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发表时间：
2015-04-01
期刊：
影响因子：
4
通讯作者：
Ishizuka, Shigehiro
中科院分区：
文献类型：
--
作者：
Terazawa, Kazuhiko;Yamada, Kenji;Ishizuka, Shigehiro
我们进行了实地测量的空间和时间变化的CH 4排放量从成熟的水曲柳干表面。日本北方洪泛平原森林中的树木。采用静态气室法测定了2000 ~ 2005年10月30日龄林分树干CH 4通量。在10株选择的树木上，在离地面15 cm的高度上，测试了不同的个体变异性，以及3株代表性树木的日变化和季节变化。白天树干CH 4排放速率在81 ~ 1，305 A mug CH 4 m（-2）h（-1）之间，表现出明显的空间梯度，与试验点地下水位深度的差异相对应。茎CH 4通量是相当稳定的，在整个24小时内的落叶树在8月和落叶树在11月相似。在干CH 4通量的季节性变化的幅度在个别树木之间观察到很大的差异;一个采样树没有表现出明显的干CH 4通量的季节性变化，而另一棵树表现出剧烈的季节性变化范围大于一个数量级。结果表明，干CH 4排放量在空间和时间上的高变异性，并建议土壤温度，地下水位深度和孔隙水CH 4浓度的重要性，作为可能的环境因素控制干CH 4排放从温带森林湿地。
We performed field measurements on the spatial and temporal variability in CH4 emissions from stem surfaces of mature Fraxinus mandshurica Rupr. trees in a floodplain forest of northern Japan. Stem CH4 fluxes were measured by a static closed-chamber method at ca. 15 cm above ground on ten selected trees to test among-individual variability, and the diurnal and seasonal changes in three representative trees. Daytime stem CH4 emission rates varied between 81 and 1,305 A mu g CH4 m(-2) h(-1) among individual trees, and showed a spatial gradient apparently corresponding to the difference in water table depth at the experimental site. Stem CH4 fluxes were quite stable throughout a 24 h period for foliated trees in August and were similar for defoliated trees in November. Large differences were observed in the magnitude of seasonal changes in stem CH4 flux among individual trees; one sampled tree showed no clear seasonal changes in stem CH4 flux, while another tree exhibited drastic seasonal changes ranging larger than one order of magnitude. Results demonstrated the high variability in stem CH4 emissions in space and time, and suggested the importance of soil temperature, water table depth and porewater CH4 concentration as possible environmental factors controlling stem CH4 emissions from temperate forested wetlands.