藏东南色季拉山急尖长苞冷杉非结构性碳水化合物时空动态特征

目的 为了验证高山林线的形成机理,探究树木分布上限的限制因素。 方法 本研究以色季拉山急尖长苞冷杉为研究对象,在其低海拔针阔叶混交林（3 500 m）、中海拔适生区（3 900 m）和高海拔林线过渡带（4 300 m）,分别于生长季（7月初）与非生长季（11月底）测定树木叶、枝、干和根的非结构性碳水化合物（NSC）及其组分含量,以及C、N、P含量。 结果 不同生长季节急尖长苞冷杉非结构性碳水化合物源与汇含量比较稳定,未出现碳供应不足现象;海拔对急尖长苞冷杉非结构性碳水化合物及其组分影响较小;器官间NSC含量差异显著,叶、枝、干和根在不同生长季节所侧重的生理活动和功能不同;非生长季急尖长苞冷杉非结构性碳水化合物及其组分显著高于生长季,非生长季较高的可溶性糖和NSC含量有利于抵御低温等恶劣环境;急尖长苞冷杉的NSC含量随海拔的上升呈现出递增的趋势,一定程度上支持了“生长抑制”假说。 结论 色季拉山急尖长苞冷杉的生长更多的受到了植物养分的限制,而非碳限制。

Spatiotemporal Dynamic Characteristics of Non-structural Carbohydrates of Abies georgei var. smithii in Sygera Mountain

Objective To verify the formation mechanism of the alpine treeline and explore the limiting factors of the upper limit of tree distribution. Methods In the low altitude coniferous and broad-leaved mixed forest (3500 m), suitable altitude area (3900 m) and high altitude treeline transition zone (4300 m) in Sygera Mountain, the contents of non-structural carbohydrates and C, N, and P in leaves, branches, stems and roots of Abies georgei var. smithii as well as were measured both in the growing season (early July) and non-growing season (end of November). Results The results showed that the non-structural carbohydrate sources and sinks of Abies georgei var. smithii were stable in different growing seasons, and there was no insufficient carbon supply. There were little effects of altitude on the non-structural carbohydrates and their components in Abies georgei var. smithii . There were significant differences in NSC content among organs, and the physiological activities and functions of leaves, branches, trunks, and roots were significantly different in different growing seasons. In the non-growing season, non-structural carbohydrates and their components were significantly higher than those in the growing season. In the non-growing season, higher soluble sugars and NSC contents enabled the vegetation to resist cold temperature and other harsh conditions. The content of NSC in Abies georgei var. smithii increased with the increase of altitude, which supported the hypothesis “growth limitation” . Conclusion The growth of Abies georgei var. smithii is more restricted by plant nutrients than by carbon.