In situ (CO2)-C-13 labeling reveals that alpine treeline trees allocate less photoassimilates to roots compared with low-elevation trees

文献类型： 外文期刊

第一作者： Cong, Yu

作者： Cong, Yu;Bai, Edith;Liu, Kai;Han, Hudong;Dang, Yongcai;Li, Mai-He;Cong, Yu;Saurer, Matthias;Siegwolf, Rolf;Gessler, Arthur;Li, Mai-He;Gessler, Arthur;Xu, Wenhua;Xu, Wenhua;He, Hong S.

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关键词： C-13 pulse labeling; alpine treeline; carbon allocation; non-structural carbohydrates (NSC); photoassimilates; sink activity

期刊名称：TREE PHYSIOLOGY （ 影响因子：4.561； 五年影响因子：5.121 ）

ISSN： 0829-318X

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收录情况： SCI

摘要： Carbon (C) allocation plays a crucial role for survival and growth of alpine treeline trees, however it is still poorly understood. Using in situ (CO2)-C-13 labeling, we investigated the leaf photosynthesis and the allocation of C-13 labeled photoassimilates in various tissues (leaves, twigs and fine roots) in treeline trees and low-elevation trees. Non-structural carbohydrate concentrations were also determined. The alpine treeline trees (2000 m. a.s.l.), compared with low-elevation trees (1700 m a.s.l.), did not show any disadvantage in photosynthesis, but the former allocated proportionally less newly assimilated C belowground than the latter. Carbon residence time in leaves was longer in treeline trees (19 days) than that in low-elevation ones (10 days). We found an overall lower density of newly assimilated C in treeline trees. The alpine treeline trees may have a photosynthetic compensatory mechanism to counteract the negative effects of the harsh treeline environment (e.g., lower temperature and shorter growing season) on C gain. Lower temperature at treeline may limit the sink activity and C downward transport via phloem, and shorter treeline growing season may result in early cessation of root growth, decreases sink strength, which all together lead to lower density of new C in the sink tissues and finally limit the growth of the alpine treeline trees.

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