Knowledge Resource Center for Ecological Environment in Arid Area
| 针叶树种径向生长对环境变化响应的区域对比 | |
| 其他题名 | The response of conifer tree radial growth to environment change in different regions |
| 汪洋 | |
| 出版年 | 2016 |
| 学位类型 | 博士 |
| 导师 | 邵雪梅 |
| 学位授予单位 | 中国科学院大学 |
| 中文摘要 | 森林作为陆地生态系统的重要组成部分，储存了整个陆地生态系统中45%的碳，在全球的碳循环中发挥着重大的作用。随着气候变化和大气二氧化碳浓度升高，森林生态系统的动态变化和演替必然会受到一定的影响。大量的控制实验的结果，随着气候变化和二氧化碳浓度升高，树木的径向生长速度会增加，同时水分利用效率也会显著增加，但是近年来利用树轮宽度数据和数据碳同位素数据得到的结果其不同。尤其在干旱和半干旱区，虽然水分利用效率增加，但是树木径向生长没有增加。我国西北部高原地区，是全球变化的敏感区之一，在该区域上树木径向生长与水分利用效率之间的关系仍然不得而知。为此，我们通过这一地区不同干湿条件下的四条树轮BAI序列和四条树轮δ13C序列，来分析树木径向生长和水分利用效率之间的关系。研究通过本研究，得出了以下主要结论：（1）不同干湿环境条件的区域上祁连圆柏的径向生长存在差异，在相对湿润环境条件，其树木径向生长较快。祁连圆柏的BAI序列与气候要素的关系在不同区域上存在一定的相似性，其中降水条件对其影响作用较大。不同干湿环境条件的区域上两种云杉的向生长也存在差异，在相对湿润环境条件，其树木径向生长较快。云杉的BAI序列与气候要素的关系在不同区域上的差异较大，在较为湿润地区主要受生长季温度的影响，而在较为干旱的地区主要受到生长季降水的影响。（2）四条树轮δ13C序列都出现了明显的下降趋势，尤其是近几十年，这种下降趋势更加明显。云杉树轮δ13C的值要比祁连圆柏的更加小，说明了云杉相比祁连圆柏要更加耐旱。不同干湿环境条件的区域上祁连圆柏的树轮δ13C序列与气候要素的关系近似，都是与生长季的温度正相关与生长季降水负相关。而云杉的树轮δ13C序列，在不同干湿环境条件的区域上没有一致的关系。（3）云杉的水分利用效率与其径向生长存在显著的正相关，说明了水分利用利用效率的增加促进了云杉的径向生长。同时，水分利用效率与大气二氧化碳浓度的相关性非常高，说明了大气二氧化碳浓度升高是影响水分利用效率变化的主要因素。二氧化碳的肥化作用在两个云杉样点上较好地表现出了作用。相反的，祁连圆柏的水分利用效率与其径向生长存在显著的负相关，说了水分利用效率的增加没有促进祁连圆柏的径向生长。（4）在不同干湿环境条件的区域上，不同树种的叶片内外二氧化碳浓度比值（Ci/Ca）基本保持不变，说明了树木都采取了一种主动适应的方式，来适应大气二氧化碳浓度的升高。但是青海云杉在进60年以来，适应方式发生了变化，从叶片内外二氧化碳浓度比值（Ci/Ca）基本保持不变转变为叶片内部二氧化碳浓度（Ci）不变。这说明了，在未来二氧化碳浓度不断增加时，树木的适应策略可能会发生改变。 |
| 英文摘要 | Since forests are the major components of terrestrial ecosystem, it plays an important role in the global cabon cycle. It contains over 45% carbon in the terrestrial ecosystem. Consequences of climate change and increasing atmospheric CO2 concentration on forest ecosystems are already visible worldwide.Results from the controlled experiments show that the tree radial growth rate and the intrinsic water-use ef?ciency (iWUE) would increased, when the climate changed and the concentration of CO2 in atmospheric increased.Howerver, results from tree-ring width data and tree-ring δ13C data show that the radial growth rate would decreaed while the iWUE increasing.It is more common to be find in the arid and semi-arid area. In the northwest of China, it is sensitive to the climate change and increasing atmospheric CO2 concentration. It is still unknown about the relationship between tree radial growth rate and iWUE.In the present study, we develop four BAI series and four Tree-ring δ13C series to evaluate their radial growth and iWUE variations respond to the climate change and atmospheric CO2 concentration raising. The main conclusions are followed:(1) The radial growth rate of Qilian juniper was different in different climate conditions, where the weather was more humid, the radial growth rate was faster. The relationship between BAI of Qilian juniper and climate factors was the same in the large area.The precipitation was the main factor controlled the radial growth rate. The radial growth rate of spruce was different in different climate conditions too.Howerver, the relationship between BAI of Qilian juniper and climate factors was quit different in the large area. In humid area, the temperature was the most important climate factor, but in arid area, the precipitation was the the most important climate factor.(2) Four Tree-ring δ13C series show an obviously decreaed trend, especially in the recent decades. The mean value of Tree-ring δ13C for spruce was low than Qilian juniper’s value, which indicated spruce was more arid tolerant than Qilian juniper. The relationship between Tree-ring δ13C series of Qilian juniper and climate factors was almost the same in large area. Tree-ring δ13C series was postivly correlated with temperature in the growing season and with precipitation in the growing season. However, the relationship between Tree-ring δ13C series of spruce and climate factors was not the same in the large area.(3) The positive relationship between iWUE and BAI of spruce indicated that iWUE promote the BAI. Meanwhile, the relationship between iWUE and Ca was significant, which indicated Ca was the main control factors of iWUE. The CO2 fertilization effect worked in the two spruce sites. On the contrary, the iWUE of Qilian juniper was negatively correlated with the BAI. It indicated that the increasing iWUE do not accelerate the tree radial growth rate.(4)In different environmental area, the Ci/Ca was almost stable in different tree species. It exhibit that trees use a positive way to response the increasing Ca. However, in the recent decades, the Qinghai spruce changed its strategy to response the increasing Ca.The Ci value was almost unchanged, while the Ci/Ca decreased. This phenomenon indicated that trees would change their physiology process when Ca still increasing. |
| 中文关键词 | 树木径向生长 ; 断面积指数 ; 气候变化 ; 二氧化碳浓度升高 ; 树轮δ13C ; 水分利用效率 |
| 英文关键词 | Tree radial growth Basal area increment(BAI) Climate change rising concentration of CO2 in atmosphere Tree-ring δ13C intrinsic water-use ef?ciency (iWUE) |
| 语种 | 中文 |
| 国家 | 中国 |
| 来源学科分类 | 自然地理学 |
| 来源机构 | 中国科学院地理科学与资源研究所 |
| 资源类型 | 学位论文 |
| 条目标识符 | http://119.78.100.177/qdio/handle/2XILL650/287662 |
| 推荐引用方式 GB/T 7714 | 汪洋. 针叶树种径向生长对环境变化响应的区域对比[D]. 中国科学院大学,2016. |
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