贡嘎山高山林线动态与生理形成机制

Alpine Timberline Dynamics and Physiological Mechanisms of the Timberline Formation on the Mt.Gongga

作为典型的生态交错带,高山林线因其特殊的结构、功能及对气候变化的高度敏感性,已成为全球气候变化研究的热点之一。本文分析了贡嘎山高山林线动态,林线峨眉冷杉径向生长与气候变化的关系;基于贡嘎山地区现有的峨眉冷杉、川西云杉、川滇高山栎3个林线树种非结构碳水化合物(NSC)测定,探讨了贡嘎山高山林线形成生理机制,贡嘎山地区林线树木可能遭受冬季碳限制,"碳源与碳汇"的平衡关系影响高山林线的位置与分布,生长在高山恶劣环境条件下林线树种的发育和幸存,不仅依赖于最小需求的NSC浓度,而且要求冬季高于3的可溶性糖:淀粉比率,以成功越冬和维持其正碳平衡;指出了今后应重点关注气候变化背景下区域尺度高山林线动态长期观测与模拟、高山林线树木对极端环境的生理生态适应机制、高山林线森林植被碳源-汇关系的长期监测等研究。

As a kind of typical ecotone,alpine timberline has become one of the major concerns in global climate change studies because of its special structure,function and high sensitivity to climate change.An increased understanding on physiological mechanism of timberline formation is of great importance in forecasting timberline dynamics under future climate change.This paper analyzed the dynamic of alpine timberline on the Mt.Gongga,and treeline（Abies fabri） radial growth trends and their relationship with climate change.Based on the previous non-structural carbohydrates（NSC） determination in 3 timberline tree species（A.fabri,Picea likiangensis var.balfouriana,Quercus semicarpifolia） on the Gongga mountain,the physiological mechanism of the alpine timberline formation were briefly summarized.The results of the combined treelines species showed that the treeline trees may suffer from a winter carbon shortage.The source capacity and the sink capacity of trees influence its tissue NSC concentrations and the carbon balance.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.The future research should be focused on the long term observation and simulation of alpine timberline dynamics on the regional scale under climate change,physio-ecological adaptation of timberline trees to extreme harsh environment,and long-term monitoring of relationship between the carbon source and the carbon sink in the timberline forest vegetation.