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title: 尼泊尔中部和横断山地区高山树线动态变化、树木生长及 对气候变化的响应
Other Title: Alpine Treeline Dynamics and Growth Climate Response in Central Nepal and Hengduan Mountain of China
author: Achyut Tiwari
Advisor: 周浙昆;  范泽鑫
Issued Date: 2016-11
Keyword: 泛喜马拉雅;  横断山;  树线;  林线;  生态交错区;  生长气候响应;  基底面积增量;  树线变化;  更新 III
Major: 生态学
Abstract: 高山树线处在森林生态系统所能适应的极限位置,对全球变化的响应最为敏感。高山树线变化是反应森林动态变化和树木生长对气候变化相应的一个可靠指标,其对剧烈气候变化的响应是一个复杂过程。通过统计群落交错的林龄结构、林木更新能力可以揭示树线动态变化,而树木年轮则能揭示树木生长变化的气候限制因子。为了探讨树线对气候的响应,本研究在尼泊尔境内喜马拉雅中部(包括Chimang和Lete两个采样点)和中国境内的横断山中部(包括云南天宝山和四川乡城两个采样点)两个不同地区树线群落交错带(海拔3439-4490 米)和树线以下森林内部选择了四个不同树种进行采样调查。包括:西藏冷杉(Abies spectabilis)、糙皮桦(Betula utilis)、长苞冷杉(Abies georgei)、红杉(Larix potaninii)。通过统计这些树种的成年木材的年轮,幼苗和幼树的顶芽,建立了他们的种群统计结构。并且通过分析不同气候因子和树木生长的关系,揭示了该地区树线动态变化的限制因子。
研究表明在尼泊尔中部的西藏冷杉(Abies spectabilis)和糙皮桦(Betula utilis)幼苗有较高的更新速率,再更新惯性及定居速率,表明过去有持续的树线变化,未来的树线也可能有较大的变化。而横断山区中部云南天宝山的长苞冷杉(Abies georgei)和四川乡城县的红杉(Larix potaninii)则显示较低的幼苗更新速率和更新惯性率,但也有树线的变化。树木年轮分析结果表明:尼泊尔地区树线附近的树木生长主要对气候的湿润程度更为敏感,而横断山地区的树木主要受到温度的控制。根据研究我们可以推断在尼泊尔中部地区降雨量增加以及温暖的气候将会促进树木的更新,而在横断山区温度增加将促进林木的更新。本研究结果表明不同物种在不同地区的树线动态变化树线的动态变化主要是受气候因子(温度和湿度)的驱动,同时也和小环境和生物的相互作用密切相关。所以只有通过详细分析不同树龄,不同研究地点的环境因子(土壤温度和湿度),以及生物因子之间的相互作用,才能对气候变化背景下的树线的动态变化进行准确的预测。

English Abstract: The response of altitudinal treelines is considered reliable indicators of the effects of climate on tree growth and forest dynamics in the rapidly changing climate. Demographic response including stand age structure and regeneration potential of tree species in treeline indicate treeline dynamics, and tree ring records of these forests show the growth limiting climatic processes. To find out how do treeline trees respond to changing climate, we studied different tree species (Abies spectabilis, Betula utilis, Abies georgei and Larix potaninii) in Trans-Himalayan zone, Nepal and Hengduan mountain, China. Trans-Himalaya included Chimang and Lete treeline sites, wheras Hengduan region included Tianbao Mountain and Xiangcheng treelines sites. We reconstructed the age structure of tree by counting the yearly formed rings in cross-section of stem, and also by terminal buds count for seedlings and saplings. Limiting climatic factors for tree growth were identified by most closely linked periods of low and high growth in alpine treeline ecotone and proximity of timberline forest. The growth response showed that treeline is moisture sensitive in trans-Himalayan zone, Nepal and is temperature sensitive in Hengduan zone, China. There were abundant seedling recruitment, greater regenerative inertia and colonization with consistent range shift of the A. spectabilis and B. utilis treeline in Nepal, and lower seedling recruitment with lower regenerative inertia but still shifting treelines of A. georgei (Tianbao Mt.) and L. potaninii treeline (Xiangcheng) in China. From our study we concluded that treeline dynamics is driven mainly by temperature and moisture climate, and is also highly sensitive to modifying factors such as microhabitat conditions despite of climatic suitability. Closer examination of belowground environment (soil temperature and moisture), separately to juveniles and adults, as well of detail study of biotic interactions are equally important for making accurate prediction on treeline dynamics to changing climate.
Degree Level: 博士
Place of Degree's Grantor: 北京
Grantor: 中国科学院研究生院
Content Type: 学位论文
URI: http://ir.xtbg.org.cn/handle/353005/10289
Language: 英语
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Recommended Citation:
Achyut Tiwari. 尼泊尔中部和横断山地区高山树线动态变化、树木生长及 对气候变化的响应[D]. 北京. 中国科学院研究生院. 2016.
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