Knowledge Resource Center for Ecological Environment in Arid Area
| 大兴安岭落叶松樟子松径向生长和稳定碳同位素比率对气候变化响应差异研究 | |
| 其他题名 | Species-specific response of Dahurian larch (Larix gmelinii) and Mongolian pine (Pinus sylvestris var. mongolica) radial growth and stable carbon isotope to climatic change in the Great Higgnan Mountains, northeastern China |
| 张轩文 | |
| 出版年 | 2017 |
| 学位类型 | 硕士 |
| 导师 | 刘晓宏 |
| 学位授予单位 | 中国科学院大学 |
| 中文摘要 | 大兴安岭地区处于半干旱区与半湿润区的交界处，是典型的季风气候区，属于中国的第二大冻土区兴安-长白冻土区。2001-2010年，我国东北森林覆盖面积约为我国林地面积的30%，表明我国东北森林在我国碳循环过程中占据着举足轻重的地位。研究这一区域过去长时间尺度的气候变化，对于理解区域干旱变化机制、预测区域干湿变化、森林生长动态变化等有重要的意义。本研究以大兴安岭北部根河、呼中和汗马冻土区生长的落叶松和樟子松为样本，获取了年分辨率的落叶松和樟子松树轮宽度和稳定碳同位素(δ13C)序列 ;以近64年的器测气候资料(1951-2014)为基础，分析了落叶松和樟子松树木径向生长和树轮δ13C序列记录过去气候变化信息，探讨了树木对气候变化和大气CO2升高的生理响应。得出以下主要结论：(1) 在过去的64年，多年冻土区和季节冻土区的边界处有明显的变干趋势。仅在黑龙江中游地区有明显的变干趋势，其余地区的干湿变化不明显。周期分析表明，研究区干湿变化存在周期性振荡，可能与ENSO事件有关。代表松嫩平原北部地区的标准化降水蒸散指数(SPEI)第一主成分与海表温度(SST)的空间相关发现，冬半年赤道海温对该地区的湿度影响较大。当有El Ni?o事件发生时，松嫩平原北部地区较为湿润，当有La Ni?a事件发生时，该地区较为干旱。(2) 树轮宽度-气候响应关系分析表明，在全球变暖背景下，水热环境改变使得冻土区树木生长限制因子发生变化。气温为该地区落叶松和樟子松生长的主要限制因子；但二者对气候变化的响应存在差异。落叶松径向生长与3月平均气温，樟子松径向生长与前一年12月～当年4月平均气温均呈显著负相关。考虑到水热综合影响，落叶松径向生长的限制因子由1957~1990年1月SPEI转变为1991~2013年1~4月SPEI和与3月份平均气温的共同影响；樟子松径向生长的限制因子则由1957~1990年2月和8月平均气温转变为1991~2013年7月份降水量和6~7月SPEI。(3) 大兴安岭落叶松和樟子松δ13C序列与气候响应分析结果表明，落叶松年轮δ13C主要受到水热综合作用的影响，樟子松的则受到气温的影响较大。根据落叶松δ13C与气候要素的关系重建了1800~2010年7~8月的sc_PDSI，表明从1800年以来，研究区7~8月有明显的变干趋势，相较于20世纪，大兴安岭北部地区19世纪相对较湿。在长时间尺度上，当NAO处于正位相(强年)或El Ni?o事件时，区域相对较湿润；当NAO处于负位相(弱年)或La Ni?a事件时，区域相对偏干。 (4) 主动响应模式(Ci/Ca恒定)是落叶松和樟子松最主要长期水分利用效率呈现方式。1930~1990年，水分利用效率的增加对树木生长促进作用并没有弥补水热压力对树木生长的抑制作用。1990年以后，气温升高速率减缓，水分利用效率加速上升，使得落叶松和樟子松的生长恢复，而樟子松对于气温的更加敏感使得其径向生长恢复速率大于落叶松。 |
| 英文摘要 | The Great Higgnan Mountains is located at the border of semi-humid and semi-arid, belonging to the Xing’an-Baikal permafrost which is the second-largest expanse of permafrost in China. The study region is characterized by the typical monsoon climate. Forests covering the northeast China occupy about 30% of the national ecosystems from 2001 to 2010, and it plays key roles in the carbon cycle in China. It is important to explore the past climate changes in detailed for understanding the mechanism of drought variability, predicting drought events and agriculture management. Therefore, base on the Dahurian Larch (Genhe, Hanma and Huzhong) and Pinus sylvestris (Genhe and Huzhong) samples from the Great Higgnan Mountains, we obtained two regional ring width and stable carbon isotope chronologies (δ13C) from Dahurian Larch and Pinus sylvestris. We firstly analyzed the regional climate change in the Great Higgnan Mountains during the past 64 years (1951-2014) based on the observed meteorological data. After that, we explored the climatic signals recorded in the tree-ring δ13C series and physiological response to climate and atmospheric CO2, and the mainly achivements are as following:(1) Since 1951, the annual Standard Precipitation and Evaporation Index (SPEI) decreased significantly at the boundary between regions with seasonal soil freezing and permanent permafrost, suggesting that conspicuous permafrost degradation and moisture loss has occurred. However, only the middle reaches of the Heilongjiang River showed an obvious long-term drying trend. The four areas showed quasi-periodic oscillation, and sea surface temperature (SST) during the winter half-year affected drought intensity in the northern of Songnen Plains. When El Ni?o strengthened, moisture conditions increased in the northern of Songnen Plains, whereas stronger La Ni?a events decreased water availability. The observed changes in moisture conditions will strongly affect regional forest-growth dynamics, agricultural production, and carbon cycling.(2) The climatic response analysis showed that the temperature was the dominant factor affecting the tree growth in this region, but with the distinct responses of two species to climate change. Dahurian Larch radial growth were significantly and negatively correlated with the monthly average temperature in March. Pinus sylvestris radial growth were significantly and negatively correlated with the monthly averaged temperature from previous December to current April.The climate limiting factor on the radial growth of Dahurian Larch transformed from a significant negatively correlation with SPEI index in Janurary from 1957 to 1990 into a significant correlation with SPEI index from Janurary to April and temperature in March from 1991 to 2013, and the climate limiting factor for Pinus sylvestris changed from a significant negative correlation with February and August temperatures from 1957 to 1990 to a significant correlation with precipitation in July and SPEI index from June to July from 1991 to 2013. These results indicated that the two species responded to climate change, espcilly at temperature, in the different degrees under the background of global warming, even the climate limiting factor on radial growth will change in different periods for the same species.(3) The response of tree-ring stable carbon isotope (δ13C) showed that Dahurian larch carbon isotope was a significantly negative correlation with relative humidity in summer from 1957 to 2010, and Mongolian pine δ13C was significantly positive correlation with maximum temperature from June to July from 1957 to 2010. The results also showed that Dahurian larch is mainly affect by the common effect of temperature and moisture stress whereas Mongolian pine was mainly affect by temperature. According to the relationship of Dahurian larch carbon isotope and sc_PDSI from July to August from 1957 to 2010, we reconstructed sc_PDSI from July to August from 1800 to 2010. The result indicated that the average sc_PDSI from July to August had an obvious dry trend since 1800. Compared with the 20th century, the Greater Hinggan Mountains had a relatively wet environment in the 19th century. In the long time scales, when El Ni?o or NAO strengthened, moisture conditions increased whereas stronger La Ni?a events or NAO weaker, the study area water will decrease. (4) As a result, both species exhibited a physiological response that resulted in constant or nearly constant Ci/Ca. The increased iWUE caused by increasing Ca will not improve tree growth suf?ciently to compensate for temperature-induced water stress in the permafrost region of northeastern China before 1990s. The warming hiatus of and slowing down temperature-induced water stress resulted in tree radial growth recovery since 1990s in the permafrost region of northeastern China. |
| 中文关键词 | 树木径向生长 ; 树轮稳定碳同位素 ; 长期水分利用效率(iWUE) ; 东北冻土区 |
| 英文关键词 | ree radial growth tree-ring stable carbon isotope intrinsic water-use efficiency (iWUE) freeze soil of northeast in China |
| 语种 | 中文 |
| 国家 | 中国 |
| 来源学科分类 | 气象学 |
| 来源机构 | 中国科学院西北生态环境资源研究院 |
| 资源类型 | 学位论文 |
| 条目标识符 | http://119.78.100.177/qdio/handle/2XILL650/287973 |
| 推荐引用方式 GB/T 7714 | 张轩文. 大兴安岭落叶松樟子松径向生长和稳定碳同位素比率对气候变化响应差异研究[D]. 中国科学院大学,2017. |
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