藏东南色季拉山林线植物非结构性碳水化合物的季节变动  

Seasonal variation in non-structural carbohydrates of timberline plants in the Sygera Mountain,southeast Tibet

作　　者：樊志颖 李江荣[1,2,3] 陈康 汪汉驹 丁慧慧[1,3] 陈文盛 FAN Zhiying;LI Jiangrong;CHEN Kang;WANG Hanju;DING Huihui;CHEN Wensheng(Institute of Plateau Ecology,Tibet College of Agriculture and Animal Husbandry University,Linzhi,Tibet 860000,China;Tibet Key Laboratory of Forest Ecology in Plateau Area,Ministry of Education,Linzhi,Tibet 860000,China;National Key Station of Field Scientific Observation and Experiment,Linzhi,Tibet 860000,China)

机构地区：[1]西藏农牧学院高原生态研究所,西藏林芝860000 [2]西藏高原森林生态教育部重点实验室,西藏林芝860000 [3]西藏林芝高山森林生态系统国家野外科学观测研究站,西藏林芝860000

出　　处：《西北农林科技大学学报（自然科学版）》2022年第3期40-48,共9页Journal of Northwest A&F University(Natural Science Edition)

基　　金：西藏自治区自然科学基金项目“藏东南林线微气候特征及其对天然更新的影响”(XZ2018ZR G-16);西藏林芝森林生态站基准站与冻土自动监测系统建设项目(502219001);科技部国家野外科学观测研究站(生态系统)运行补助项目“西藏林芝高山森林生态系统国家野外科学观测研究(2015-2020)”。

摘　　要：【目的】研究高山林线植物非结构性碳水化合物(NSC)含量的变化,以更好地揭示高山林线的形成机制。【方法】以藏东南色季拉山林线过渡带的5种木本植物(阳坡:乔木方枝柏,灌木林芝杜鹃和雪层杜鹃;阴坡:乔木急尖长苞冷杉,灌木雪山杜鹃)为研究对象,在生长季(8月初)与非生长季(11月底)分别取其树叶、树枝、树干(方枝柏和急尖长苞冷杉)、树根等组织,测定并分析其NSC含量。【结果】林线过渡带植物在整个生长周期都有充足的NSC,生长季植物NSC含量在2.74%~3.56%,非生长季NCS含量是生长季的2.85~3.84倍。生长季5种林线过渡带植物的NSC源/汇值为1.12~1.79;非生长季2种乔木NSC含量的NSC源/汇值均大于1,表明植物碳供应充足;3种灌木植物的NSC源/汇值均小于1,表现为碳供应不足。低温等不良环境是导致非生长季植物可溶性糖与淀粉比值较生长季明显升高的主要因素;非生长季林线过渡带植物可溶性糖含量是生长季的2.64~7.66倍,而高水平的可溶性糖含量和可溶性糖与淀粉间持续的动态转化都是植物顺利过冬的保障。【结论】构成色季拉山林线的方枝柏和急尖长苞冷杉在生长季与非生长季均未表现出碳供应不足的现象,“生长抑制”和“更新繁殖障碍限制”两种假说能很好地解释藏东南色季拉山林线的形成机制。【Objective】To better reveal the formation mechanism of timberline,the variations of non-structural carbohydrate(NSC)content in the timberline were studied.【Method】Five timberline woody plants in Sygera Mountain(Juniperus saltuaria,Abies georgei var.smithii,Rhododendron aganniphum,Rhododendron nivale and Rhododendron nyingchiense)were selected and leaves,branches,trunks(J.saltuaria and A.georgei var.smithii)and roots were collected to determine and analyze NSC contents in the growing season(early August)and non-growing season(end of November).【Result】Plants in the timberline had sufficient NCS throughout their growth cycle,and NCS content of plants in the growing season was 2.74%-3.56%,while that in the non-growing season was 2.85-3.84 times of that in the growing season.The source/sink values of NSC in the timberline plants in the growing season were 1.12-1.79.The NSC source/sink values of the two trees in the non-growing season were greater than 1,indicating that plants had sufficient carbon supply.However,NSC source/sink values of the three shrubs in the non-growing season was less than 1,indicating insufficient carbon supply.Low temperature and other unfavorable environments were the main factors causing higher ratio of soluble sugar to starch in the non-growing season.The soluble sugar content in the timberline in the non-growing season was 2.64-7.66 times higher than that in the growing season,and the high level of soluble sugar content and continuous dynamic transformation between soluble sugar and starch were guaranteed smooth wintering of plants.【Conclusion】The J.saltuaria and A.georgei var.smithii of the sygera Mountain timberline had sufficient carbon supply in the growing and non-growing seasons.The two hypotheses of“growth inhibition”and“reproductive barrier restriction”can well explain the formation of timberline in the Sygera Mountain in southeastern Tibet.

关 键 词：高山林线 林线过渡带 非结构性碳水化合物 急尖长苞冷杉 方枝柏 色季拉山 

分 类 号：Q948.11[生物学—植物学]