亚热带同质园11个树种新老叶非结构性碳水化合物含量比较

叶片中非结构性碳水化合物(NSC)不仅是植物维持代谢活动的重要物质基础, 也随凋落物归还土壤并为土壤微生物提供碳源, 对凋落物分解和土壤有机质形成具有重要意义。该研究比较了同质园中11个亚热带代表性树种新鲜叶与凋落叶NSC (可溶性糖、淀粉)含量。结果表明, 所有树种新鲜叶NSC含量均显著高于凋落叶, 新鲜叶中NSC含量为68.7-126.3 mg?g^-1, 而凋落叶中NSC含量为31.4-79.5 mg?g^-1。同时, 可溶性糖含量在新鲜叶和凋落叶中的变化幅度均远大于淀粉: 可溶性糖在新鲜叶中的平均含量是凋落叶的3.3倍; 而淀粉在新鲜叶中的平均含量仅为凋落叶的1.2倍。另外, 对不同功能类群的比较发现, 常绿阔叶树种与落叶阔叶树种NSC含量差异并不显著, 而针叶树种NSC含量明显低于阔叶树种。具体表现为: 在新鲜叶中, 常绿阔叶、落叶阔叶树种NSC含量平均为99.7和96.8 mg?g^-1, 而常绿针叶树种平均为75.4 mg?g^-1; 在凋落叶中, 常绿阔叶、落叶阔叶树种NSC含量平均为47.2和50.7 mg?g^-1, 而常绿针叶树种平均为33.3 mg?g^-1。这些结果表明, NSC作为林木碳代谢组分, 在叶片衰老前可能向新鲜叶转移, 反映了林木叶片碳存储策略。然而, 不管是新鲜叶还是凋落叶, 杉木(Cunninghamia lanceolata)、马尾松(Pinus massoniana)等针叶树种叶片NSC含量显著低于阔叶树种, 这可能降低这些针叶树种凋落叶初始基质质量。

Difference in non-structural carbohydrates between fresh and senescent leaves of 11 tree species in a subtropical common-garden

Aims Non-structural carbohydrates (NSC) are available carbon in plants and can be utilized as an energy source during plant metabolism, so NSC are important components for plant growth and metabolic activities, particularly under environmental stress. Moreover, NSC in senescent leaves as litter-fall provide available carbon for soil microorganisms involving in soil organic matter formation and biogeochemical cycles in forests. Therefore, study on the variation in NSC between fresh and senescent leaves is of great significance for understanding the carbon metabolism during plant growth and carbon biogeochemical cycles during early decomposition of plant litter. The objective of this study was to determine the difference in NSC content between fresh and senescent leaves of 11 subtropical tree species and the variation between leaves with different plant functional types.