【作者】 李轶冰；

【导师】 杨改河；

【作者基本信息】 西北农林科技大学 ， 生态学， 2006， 博士

【摘要】 中华文明两大母亲河的发源地江河源区日益突出的生态环境问题近年来倍受关注,政府和科研界加大了保护的投入和探索。研究该区生态环境演变过程及其规律,是科学评价该区生态环境地位和质量、进行针对性生态环境保护的必要前提。以生态环境内涵和生态环境演变理论探索与总结为基础,结合连续三年(2002～2004年)实地考察、大量文献收集与查阅、年轮分析、气象遥感资料和观测资料分析,进行了研究区地质时期生态环境演变、近代环境变化、生态系统时空格局、生态环境地位和生态系统主体等方面的研究与探讨,得出了以下主要成果和结论:作为青藏高原的有机组成部分和南北植物区系的过渡地带,江河源区生态环境演变与时空格局是全球气候变化和青藏高原隆起的宏伟巨作。江河源区在泥盆纪至三叠纪为浅海环境,一些岛屿发育热带雨林,侏罗纪至白垩纪逐渐成陆。第三纪为亚热带环境,始新世早期气候干燥,中期温暖湿润,后期随高原早期隆起(海拔约500 m)变得炎热干燥并维持至渐新世初期,渐新世中晚期相对温暖潮湿,渐新世末随高原隆升(约500～1 000 m)和全球气候变冷而降温变干,始新世至渐新世东南至西北依次为森林(囊谦)、灌丛草原(玛多)、荒漠草原和干旱草原,以干旱植被为主,青藏公路附近和囊谦地区发育古湖;中新世早期至上新世中期,在地中海气候和印度洋季风气候影响下温暖湿润,亚热带森林和森林草原广布,古湖发育扩展至治多、达日、甘德、贵德、同仁和泽库等地。上新世晚期至第四纪早更新世初,高原强烈大面积隆升(1 000 m升至2 000 m),冰川出现,短暂寒冷干燥之后恢复暖湿,江源区随气候波动出现森林和草原的更替,江源区南缘随气候波动出现阔叶林-针叶林-阔叶林的更替,黄河源区为亚热带山地针叶林。早更新世末至中更新世初,高原强烈隆升(3 000 m),其中昆仑山垭口隆升剧烈(1 500 m升至4 500 m),环境接近现代,江河源区抬升(黄河源3 500 m)中,化隆段黄河、鄂陵和扎陵湖盆地初成,气候变干冷,第一次冰期发生,以干旱草本为主,随后间冰期时间较长,温暖湿润,江源区森林植被恢复,鄂陵和扎陵盆地进一步隆升中断陷成湖。中更新世中期,倒数第二次冰期发生,规模明显小于上次,多年冻土广泛发育;随后的间冰期江源区和河源区分别为灌丛/疏林草原和疏林草原,晚更新世初,森林在高原隆升(4 000 m)中进一步减少。晚更新世中晚期的末次冰期分2次冰阶进行,多年冻土三度扩展,在构造运动作用下现代水系格局形成,在间冰阶,尤其中后期,在特强夏季风气候影响下,出现泛湖期,植被状况好于全新世大暖期。最早的人类活动证据出现在第2更多还原

【Abstract】 Yangtze and Yellow Rivers are regard as the mother rivers of China. So the recent enrionmental degradation of source regions of Yangtze, Yellow and Lancang Rivers get more attention from government and research field who put more devotion to improve it. The research of its environment evolvement is the basic premise of its environmental status and quality asseeement as well as equal protection.Based on the summings-up of the theory of environment evolvement, by way of 3 years’fieldwork (2002～2004), literature search, tree’s growth ring analysis, meteorologic remote data analysis and meteorologic observation data analysis, the environment evolvement in geological time, the environment changes recently, environmental status, spatio-temporal patterns of ecosystems, determinant ecosystem of research area are researched and discussed. The results are as following:As the part of Qinghai-Tibetan Plateau and its transitional zone between north fauna and south fauna, environment evolvement and spatio-temporal patterns of ecosystems of research area is the outcome of globe climate changes and upheaval of Qinghai-Tibetan Plateau. It was shallow sea with some islands that developed tropical rain forest during Devonian and Triassic. It was becoming land during Jurassic and Cretaceous. It was sub-tropical climate in Tertiary. It was dry in early Eocene, warm and wet in middle Eocene. Then it became dry again in late Eocene and early Oligocene because of Plateau’s early upheaving (500 m). It went into warm and wet in middle and late Oligocene. It became dry and cool again due to upheaving (500～1 000 m) and globe climate colding. There were forest (Nangqian), shrub steppe (Maduo), desert steppe from southeast to northwest during Eocene and Oligocene. Immemorial lakes was developed in Nangqian and area around modern Qinghai-Tibetan road. From early Miocene to middle Pliocene, it was quite warm and humid under the influence of Mediterranean climate and Indian Ocean monsoon climate, thus sub-tropical forest and forest steppe distributed far and wide, and immemorial lakes expanded to Zhiduo, Dari, Gande, Guide, Tongren and Zeku. From late Pliocene to the very early-Pleistocene in Quaternary, Plateau upheaved mightily (from 1 000 m to 2 000 m), glacier appeared, it reverted to warm and wet after short time of cold and dry. Vegetation succession emerged with the climate更多还原