Variations in leaf delta C-13 along a vertical profile of irradiance in a temperate Japanese forest
Variations in leaf delta C-13 along a vertical profile of irradiance in a temperate Japanese forest
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DOI：
10.1007/s004420050158
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发表时间：
1997-04-01
期刊：
影响因子：
2.7
通讯作者：
Wada, E
中科院分区：
文献类型：
--
作者：
Hanba, YT;Mori, S;Wada, E
对日本冷温带落叶林中 13 种树种的叶片稳定碳同位素比率 (δ(13)C) 的垂直剖面进行了分析。大气 CO2 中长期平均 δ(13)C 的垂直分布 (δ(a)) 是根据在森林塔中生长 32 天的 NADP-苹果酸酶 C-4 型植物 (Zea mays L. var. saccharata Sturt.) 的干物质 δ(13)C 估算的，假设玉米中 δ 值恒定（千分之 3.3）相对于高度。从 Z. mays 的 delta(13)C 获得的 delta(a) 值在森林地面最低（-9.30 +/- 0.03 ppm），随着高度的增加而增加，并且在 10 m 以上几乎恒定（-7.14 +/- 0.14 ppm）。然后根据树叶 delta(13)C 和 delta(a) 计算树种的叶子 Delta 值。三种高大落叶树种（水曲柳、榆树和毛桤木）的平均叶片 Delta 值在森林中三个高度水平之间存在显着差异：森林地面（林下）为 23.1 +/- 0.7 ppm，下部树冠为 21.4 +/- 0.5 ppm，上部树冠为 20.5 +/- 0.3 ppm。森林高度水平之间树叶Delta的真正差异可能更大，因为Z. mays的Delta可能会随着遮蔽而增加多达千分之一。森林高度水平之间树叶Delta的差异主要是由于随着辐照度的增加，细胞间CO2（C-i）减少。这三个物种的潜在同化率可能随着高度的增加而增加，因为这些物种的面积基础上的叶片氮含量也随着高度的增加而增加。然而，这些树种气孔导度的增加无法满足潜在同化率的增加，这可能导致光合作用的气孔限制程度随着高度的增加而增加。
The vertical profile of stable carbon isotope ratios (delta(13)C) of leaves was analyzed for 13 tree species in a cool-temperate deciduous forest in Japan. The vertical distribution of long-term averaged delta(13)C in atmospheric CO2 (delta(a)) was estimated from delta(13)C of dry matter from NADP-malic enzyme type C-4 plant (Zea mays L. var. saccharata Sturt.) grown at a tower in the forest for 32 days, assuming constant Delta value (3.3 parts per thousand) in Z. mays against height. The delta(a) value obtained from delta(13)C in Z. mays was lowest at the forest floor (-9.30 +/- 0.03 parts per thousand), increased with height, and was almost constant above 10 m (-7.14 +/- 0.14 parts per thousand). Then leaf Delta values for the tree species were calculated from tree leaf delta(13)C and delta(a). Mean leaf Delta values for the three tall deciduous species (Fraxinus mandshurica, Ulmus davidiana, and Alnus hirsuta) were significantly different among three height levels in the forest: 23.1 +/- 0.7 parts per thousand at the forest floor (understory), 21.4 +/- 0.5 parts per thousand in lower canopy, and 20.5 +/- 0.3 parts per thousand in upper canopy. The true difference in tree leaf Delta among the forest height levels might be even greater, because Delta in Z. mays probably increased with shading by up to similar to 1 parts per thousand. The difference in tree leaf Delta among the forest height levels would be mainly due to decreasing intercellular CO2 (C-i) with the increase in irradiance. Potential assimilation rate for the three species probably increased with height, since leaf nitrogen content on an area basis for these species also increased with height. However, the increase in stomatal conductance for these tree species would fail to meet the increase in potential assimilation rate, which might lead to increasing the degree of stomatal limitation in photosynthesis with height.