青藏高原东南缘地区主要现代乔木花粉沿海拔变化规律研究

Study on the Changes of Pollen of Main Modern Trees along Altitude in the Southeastern Margin of Qinghai-Xizang Plateau

摘要: 青藏高原东南缘地区作为横断山脉核心区，是全球生物多样性热点和垂直自然带谱的典型区域，其显著的海拔梯度为研究现代乔木花粉分布规律及其气候驱动机制提供了理想场所。本研究通过整合49个现代花粉样点(海拔3500~4500米)数据，结合冗余分析(RDA)和气候因子，系统揭示了主要乔木花粉沿海拔的分布模式及其与印度夏季风(ISM)的关联。结果表明：低海拔(<4000米)以松属(34.2%)、落叶栎类(15.6%)为主，其分布受温暖季节温度和干旱季降水驱动；高海拔(≥4000米)则以云杉/冷杉属(9.1%)、桦木属(12.5%)占优，与寒冷温度和湿润季降水显著正相关。铁杉属和桤木属受限于高海拔低温，而桦木属表现出强抗寒适应性。ISM通过雅鲁藏布江河谷上升气流，将低海拔松属、云杉属花粉远距离输送至高海拔区域，其强度与花粉丰度呈正相关，为古季风重建提供了生物气候档案。本研究填补了高海拔花粉现代过程研究的不足，为区域生物多样性保护、古气候定量重建及生态走廊管理提供了科学依据。

Abstract: As the core area of the Hengduan Mountains, the southeastern margin of the Qinghai-Xizang Plateau is a global biodiversity hotspot and a typical area of the vertical natural zone spectrum. Its significant elevation gradient provides an ideal place to study the distribution of modern tree pollen and its climate driving mechanism. By integrating data from 49 modern pollen samples (3500-4500 m above sea level), redundancy analysis (RDA) and climatic factors, we systematically revealed the distribution patterns of major tree pollen along sea level and its association with the Indian Summer monsoon (ISM). The results showed that pine (34.2%) and deciduous oak (15.6%) were the main species at lower altitudes (<4000 m), and their distribution was driven by temperature in the warm season and precipitation in the dry season. At high altitudes (≥4000 m), spruce/fir (9.1%) and Betula (12.5%) were dominant, and there was a significant positive correlation between cold temperature and wet season precipitation. Hemlock and alder are limited to low temperatures at high altitudes, while Birch shows strong adaptability to cold resistance. Through the updraft of the Yarlung Zangbo River valley, ISM transported pollen of pine and spruce from low altitude to high altitude areas over a long distance, and its intensity was positively correlated with pollen abundance, which provided bioclimatic archives for the reconstruction of ancient monsoon. This study fills the deficiency of modern process research of high altitude pollen, and provides a scientific basis for regional biodiversity conservation, paleoclimate quantitative reconstruction and ecological corridor management.