Non-structural carbohydrate pools in a tropical forest
Non-structural carbohydrate pools in a tropical forest
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DOI：
10.1007/s00442-004-1773-2
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发表时间：
2005-03-01
期刊：
影响因子：
2.7
通讯作者：
Körner, C
中科院分区：
文献类型：
--
作者：
Würth, MKR;Peláez-Riedl, S;Körner, C
树木中可移动碳水化合物（即非结构性碳水化合物（NSC））的池大小反映了净光合碳吸收（源）与结构不可逆投资或碳损失（汇）之间的平衡。如果考虑从根部到冠顶的所有组织，NSC 浓度的季节变化应反映库/源关系。我们使用巴拿马的史密森天篷起重机对半落叶热带森林中的 NSC 浓度进行了 22 个月的研究。在 9 个最深入研究的物种（在 17 个调查的物种中）中，我们发现所有物种和器官的 NSC 浓度（淀粉、葡萄糖、果糖、蔗糖）在旱季均高于雨季（NSC 占叶干物质的 7.2% vs 5.8%，枝干中为 8.8/6.0，茎中为 9.7/8.5，粗粒中为 8.3/6.4，干物质中为 3.9/2.2）在细根中）。由于这种增加仅归因于淀粉，我们将其归因于干旱限制的生长（光合作用受干旱影响小于库活动）。物种特定的物候节律（生叶或结果）并没有推翻这些季节性趋势。大部分茎体积（胸高直径约 40 厘米）储存 NSC。我们提出了 NSC 池大小的第一个整个森林估计，假设森林生物量为 200 t ha(-1)：其中的 8%，即约 10%。 16 t ha(-1) 为 NSC，其中约 16 t ha(-1) 为 NSC。茎和枝中 13 t ha(-1)，约 13 t ha(-1)叶和根中 0.5 和 2.8 t ha(-1)。仅淀粉（约 10.5 t ha(-1)）所产生的碳就远远多于在没有额外光合作用的情况下替换整个叶冠所需的碳。 NSC 从未经历过显着耗尽的时期。叶子冲洗并没有严重消耗 NSC 库。总体而言，数据表明该森林处于高碳供应状态，并且旱季的生长不受碳限制。相反，水资源短缺似乎直接限制了碳投资（新组织的形成），为直接的二氧化碳施肥效应留下了很小的余地。
The pool size of mobile, i.e. non-structural carbohydrates (NSC) in trees reflects the balance between net photosynthetic carbon uptake (source) and irreversible investments in structures or loss of carbon (sink). The seasonal variation of NSC concentration should reflect the sink/source relationship, provided all tissues from root to crown tops are considered. Using the Smithsonian canopy crane in Panama we studied NSC concentrations in a semi-deciduous tropical forest over 22 months. In the 9 most intensively studied species (out of the 17 investigated), we found higher NSC concentrations (starch, glucose, fructose, sucrose) across all species and organs in the dry season than in the wet season (NSC 7.2% vs 5.8% of dry matter in leaves, 8.8/6.0 in branches, 9.7/8.5 in stems, 8.3/6.4 in coarse and 3.9/2.2 in fine roots). Since this increase was due to starch only, we attribute this to drought-constrained growth (photosynthesis less affected by drought than sink activity). Species-specific phenological rhythms (leafing or fruiting) did not overturn these seasonal trends. Most of the stem volume (diameter at breast height around 40 cm) stores NSC. We present the first whole forest estimate of NSC pool size, assuming a 200 t ha(-1) forest biomass: 8% of this i.e. ca. 16 t ha(-1) is NSC, with ca. 13 t ha(-1) in stems and branches, ca. 0.5 and 2.8 t ha(-1) in leaves and roots. Starch alone (ca. 10.5 t ha(-1)) accounts for far more C than would be needed to replace the total leaf canopy without additional photosynthesis. NSC never passed through a period of significant depletion. Leaf flushing did not draw heavily upon NSC pools. Overall, the data imply a high carbon supply status of this forest and that growth during the dry season is not carbon limited. Rather, water shortage seems to limit carbon investment (new tissue formation) directly, leaving little leeway for a direct CO2 fertilization effects.