Nitrogen and carbon source-sink relationships in trees at the Himalayan treelines compared with lower elevations

• Published in: Plant, Cell & Environment
• Main Authors: Li, Mai-He, Xiao, Wen-Fa, Shi, Peili, Wang, San-Gen, Zhong, Yong-De, Liu, Xing-Liang, Wang, Xiao-Dan, Cai, Xiao-Hu, Shi, Zuo-Min
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2008
• Subjects: Altitudinal Limit; Carbon Limitation; C-balance; C-n Ratio; Growth Limitation; Non-structural Carbohydrates; Starch; Sugars; Science & Technology; Life Sciences & Biomedicine; Plant Sciences; PINUS-CEMBRA TREES; GROWTH-LIMITATION; SWISS TREELINE; TEMPERATURE; CO2; RESPONSES; SEEDLINGS; PHOTOSYNTHESIS; CARBOHYDRATE; ACCLIMATION; Arctic; The Needle
• Online Access: http://ir.imde.ac.cn/handle/131551/10537; https://doi.org/10.1111/j.1365-3040.2008.01848.x

No single hypothesis or theory has been widely accepted for explaining the functional mechanism of global alpine/arctic treeline formation. The present study tested whether the alpine treeline is determined by (1) the needle nitrogen content associated with photosynthesis (carbon gain); (2) a sufficient source-sink ratio of carbon; or (3) a sufficient C-N ratio. Nitrogen does not limit the growth and development of trees studied at the Himalayan treelines. Levels of non-structural carbohydrates (NSC) in trees were species-specific and site-dependent; therefore, the treeline cases studied did not show consistent evidence of source/carbon limitation or sink/growth limitation in treeline trees. However, results of the combined three treelines showed that the treeline trees may suffer from a winter carbon shortage. The source capacity and the sink capacity of a tree influence its tissue NSC concentrations and the carbon balance; therefore, we suggest that the persistence and development of treeline trees in a harsh alpine environment may require a minimum level of the total NSC concentration, a sufficiently high sugar:starch ratio, and a balanced carbon source-sink relationship.