Knowledge Resource Center for Ecological Environment in Arid Area
| 喜马拉雅山脉和横断山脉中部海拔梯度上树木长期生长动态及其对气候变化的响应 | |
| 其他题名 | Long-term tree growths and their responses to climatic changes along elevation gradients in the central Himalaya and Hengduan Mountains |
| SHANKAR PANTHI | |
| 出版年 | 2018 |
| 学位类型 | 博士 |
| 导师 | 周浙昆 |
| 学位授予单位 | 中国科学院大学 |
| 中文摘要 | 气候变暖和大气二氧化碳浓度升高已成为全球变化研究关注的关键问题。喜马拉雅山脉和横断山脉过去几十年经历了快速升温过程，高海拔森林可能变得越来越脆弱。然而，这些地区长期气候和环境变化特征、树木生长与气候关系仍知之甚少。特别地，气候变化背景下高海拔森林树木长期生长速率和水分利用效率将发生何种变化，仍缺乏系统的研究。结合传统树木年代学方法和树轮稳定性同位素技术，本研究旨在探明喜马拉雅山脉和横断山脉中部气候变化趋势、高海拔森林树木生长对气候的响应特征、气候变化对树木生长速率和生理调节的影响。本研究利用在喜马拉雅山脉采集的喜马拉雅云杉（Picea smithiana）年轮样品，研究喜马拉雅山中部的过去300多年的干旱变化历史。利用在喜马拉雅山脉和横断山中部采集的冷杉年轮样品，研究了的高海拔冷杉林树木径向生长的长期趋势和气候响应模式。本研究利用了传统的树轮采样、树轮宽度测量和交叉定年等技术手段。为重建区域气候历史，采用“二次去趋势”的方法合成树轮标准化年表指数。为了评估树木长期生长速率变化，我们将交叉定年后的年轮宽度序列转换为基部断面积增长量（BAI）指数。同时，我们选择不同海拔梯度上冷杉年轮样品进行年轮a-纤维素的提取和稳定性碳同位素的测量，并以此计算树木长期内禀水分利用效率（iWUE）。我们用相关函数和响应函数分析来检测树木生长对气候变化的响应模式。研究结果表明：喜马拉雅中部的喜马拉雅云杉（Picea smithiana）径向生长主要受春季可利用水分的限制，适合喜马拉雅地区春季干旱历史的重建。喜马拉雅山中部的春季干旱指数重建序列显示，自20世纪80年代初以来，该地区气候逐渐向干旱化趋势转变，与现代气象记录的区域变暖和降水减少趋势吻合。喜马拉雅山中部的春季干旱变化历史与附近区域的干湿指数和降水重建有很好的一致性，并且本研究证明喜马拉雅中部的干湿变化与北大西洋涛动（AMO）的模态转变有关。在尼泊尔西部半干旱地区的Rara国家公园(RNP)，喜马拉雅冷杉(Abies spectabilis)的径向生长与春季温度呈负相关，而与春季降水呈正相关关系。相反，在尼泊尔东部湿润区的Gaurishankar国家公园，喜马拉雅冷杉的径向生长夏季温度呈正相关。这种关系表明喜马拉雅冷杉的径向生长受到半干旱地区条件下春季水分可利用性的限制，而在喜马拉雅山中部潮湿环境条件下的夏季夏季，树木生长受益于夏季温度。同样，在横断山脉中部寒冷而湿润的高海拔地区，长苞冷杉（Abies georgei）的径向生长与夏季（七月）温度的呈正相关关系，并且相关性随海拔增高而增加。高海拔地区森林树木的长期生长速率变化趋势在不同海拔上有所不同。在尼泊尔西部地区，喜马拉雅云杉的断面积增长量（BAI）从1820年以来持续增加，但从1980年开始呈现出下降的趋势。不论在尼泊尔东部湿润区还是西部半干旱区，喜马拉雅冷杉的断面积增长量均呈不断增加的趋势。在横断山中部，低海拔长苞冷杉的断面积增长量呈不断增加的趋势，而高海拔样点的长苞冷杉断面积增长量从1950年开始呈现下降趋势。在气候变化和CO2浓度增加的背景下，不同海拔梯度上树木长期生理调节能力存在差异，导致了不同海拔梯度上生长速率变化趋势不尽一致。 关键词：断面积增长量（BAI）;喜马拉雅中部，生长-气候响应;气候波动; 树木年代气候学;海拔梯度;生长动态; 横断山; 高海拔森林;喜马拉雅冷杉;喜马拉雅云杉; 内秉水分利用效率（iWUE）;春季干旱;稳定性碳同位素 (d13C)，树木年轮;长苞冷杉 |
| 英文摘要 | Climate warming and elevated atmospheric carbon dioxide concentration ([CO2]) have become the most critical issue of global changes. High-elevation forests in high mountains of Himalayas and Hengdun Mountains could become increasing vulnerable due to higher rate of warming during the past decades. However, little is known about long-term environmental changes and growth-climate relationships of high-elevation coniferous tree species in these regions. Especially, long-term changes of tree growths and intrinsic water use efficiency of high-elevation forests under different site conditions and along elevation gradients are not explored yet in both regions. Combining dendroclimatic and stable isotopic measurements, the present study aimed to explore long-term environmental changes, growth-climate responses, growth trends of high-elevation coniferous trees and their physiological adjustment to the changing climate. Tree ring increment cores of Himalayan spruce (Picea smithiana) were collected to study the historic drought variation over the past three centuries in the central Himalaya. While, tree ring samples of high-elevation fir forests from the central Himalaya and Hengduan Mountains were collected along elevation gradients to detect an elevational trends on growth trends and growth-climate responses. Standard dendrochronological procedures were followed for sample preparation, tree ring measurements and cross-dating. For the dendroclimatic purposes, tree ring measurements were standardized into ring-width index (RWI) chronology using ‘double-detrending’ method. To the estimate long-term tree-growth trends, well cross-dated raw ring-width series were converted into basal area increment (BAI) chronology. Stable carbon isotope (δ13C) was measured from alpha-cellulose extracted from of precisely dated tree rings for different elevation bands and intrinsic water use efficiency (iWUE) were estimated. Correlation and response function analysis was performed to determine the tree growth-climate responses. Climate-growth relationship revealed tree radial growth of Himalayan spruce is strongly limited by spring moisture availability, and thus suitable for the historic spring drought reconstruction in the central Himalaya. Spring drought variability in the central Himalaya revealed a continuous shift toward drier conditions since early 1980s and coincided with continental-scale warming and reduced spring precipitation in the central Himalaya. Spring drought variability in the central Himalaya was consistent with other regional wet-dry episodes and may be linked to Atlantic Multidecadal Oscillation (AMO) activities. Tree radial growth of Himalayan fir (Abies spectabilis) showed negative (positive) correlation with spring temperatures (moisture) and the relationship revealed an elevational trend in the semi-arid site conditions of Rara National Park (RNP). However, radial growth of Himalayan fir in the humid site conditions of Gaurishankar Conservation Area (GCA) showed positive relationship with summer temperatures. Such relationships indicate that the radial growth of Himalayan fir is limited by spring moisture availability in the semi-arid site conditions, while tree growth benefit with summer temperatures during moist summer conditions in the humid site conditions in the central Himalaya. Similarly, tree growth of Yunnan fir (Abies georgei) also revealed positive relationship with summer (July mean and minimum) temperatures and the correlation showed an elevational trend with much stronger relationship at upper elevations in the cold and humid environment conditions of Hengduan Mountains. Furthermore, high-elevation forests revealed unique and variable long-term growth trends along elevation gradients. Himalayan spruce showed a rapid increase in BAI since 1820s, while growth declined unprecedently since 1980s. In the meantime, Himalyan fir revealed increasing long-term tree growth trend along elevation gradient in both semi-arid and humid site conditions. Furthermore, long-term tree growth trend of Yunnan fir has been increased in all elevations except at timberline site in the BSM, where growth was started to decline since 1950s. Tree growth could benefit the or retard or remain stable according to site conditions depending on how much could trees adjust to the changing climate and elevated [CO2] beyond optimum level. Tree growth increase/benefit upto an optimum level depending on how much could trees adjust to increasing temperatures and elevated [CO2]. Keywords: Basal area increment (BAI); Central Himalaya; Climate-growth response; Climate variability; Dendroclimatogy; Elevation gradient; Growth dynamics; Hengduan Mountains; High-elevation forests; Himalayan fir (Abies spectabilis); Himalayan spruce (Picea smithiana); Intrinsic water use efficiency (iWUE); Spring drought; Stable carbon isotope (d13C); Tree rings; Yunnan fir (Abies georgei) |
| 中文关键词 | 生长-气候响应 ; 气候波动 ; 树木年代气候学 ; 生长动态 ; 高海拔森林 |
| 英文关键词 | Climate-growth response Climate variability Dendroclimatology Growth dynamics High-elevation forests |
| 语种 | 中文 |
| 国家 | 中国 |
| 来源学科分类 | 生态学 |
| 来源机构 | 中国科学院西双版纳热带植物园 |
| 资源类型 | 学位论文 |
| 条目标识符 | http://119.78.100.177/qdio/handle/2XILL650/288050 |
| 推荐引用方式 GB/T 7714 | SHANKAR PANTHI. 喜马拉雅山脉和横断山脉中部海拔梯度上树木长期生长动态及其对气候变化的响应[D]. 中国科学院大学,2018. |
| 条目包含的文件 | 条目无相关文件。 | |||||
| 个性服务 |
| 推荐该条目 |
| 保存到收藏夹 |
| 导出为Endnote文件 |
| 谷歌学术 |
| 谷歌学术中相似的文章 |
| [SHANKAR PANTHI]的文章 |
| 百度学术 |
| 百度学术中相似的文章 |
| [SHANKAR PANTHI]的文章 |
| 必应学术 |
| 必应学术中相似的文章 |
| [SHANKAR PANTHI]的文章 |
| 相关权益政策 |
| 暂无数据 |
| 收藏/分享 |
除非特别说明，本系统中所有内容都受版权保护，并保留所有权利。
