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祁连山青海云杉对20 世纪50 年代以来 气候变化的响应分析
张永香
Subtype博士
Thesis Advisor邵雪梅
2009-01
Degree Grantor中国科学院研究生院
Place of Conferral北京
Degree Name博士
Degree Discipline自然地理
Keyword祁连山 青海云杉 20 世纪气候变化 生长分异 响应分异
Call Number无纸质版
Abstract

由于器测资料长度限制了人们对气候内在变化机制的进一步了解,借助各种代用资料就成了气候变化研究的一个重要手段。树轮资料以其高分辨率、分布广泛、易于获取副本以及可以用线性关系拟合等优势在重建过去气候变化中取得众多成果。树轮与气候要素之间存在的稳定的响应关系,是我们使用树轮资料进行气候变化研究的基础,也是树轮气候学研究的前提。20 世纪后期的全球快速升温,造成了多种环境问题和气候问题。近
期,越来越多的研究发现,生长在北半球高纬度以及中纬度山地的森林,原本其生长受温度限制,但在近半个世纪里,它们对温度的敏感性降低了,甚至树木与气候要素的响应关系也发生了转变。在中国树轮资料在研究过去气候历史变化中起着不可或缺的作用。为了探究区域树轮资料对20 世纪末的气候变化作何响应,本研究选取了青藏高原东北部对气候变化非常敏感的祁连山区作为研究区,借助了该区域内广泛分布的建群树种——青海云杉,分析了近半个世纪以来青海云杉与主要气候要素之间的响应关系及其变化特征。
本文在研究区内选取了11 个空间上的上限样点和两个坡面的7 个垂直梯度的总共
16 个点的三百多株青海云杉,讨论了自有器测纪录以来的时段树木生长与气候因子之间的响应。结果显示,近三十年来各样点内单株树木与气候要素之间的响应关系发生了显著变化。即随着时间的变化,单株树木与降水存在的一致相关出现了减弱的趋势。而树木与温度之间则出现了明显的响应分异现象。换句话说,样点内树木原本与温度的相关一致性较好,但在近三十年里二者的联系却出现了明显的分异。尤其在生长季内,它们的相关关系呈现出明显的向正、负方向分异的现象。
依据同一样点的单株树木在20 世纪末的最后三十年与温度的相互关系,我们可以将各样点内的树木聚类成不同的响应组:偏正响应、偏负响应两个小组。用不同响应组树木所建立的年表与月均温(特别是生长季内的温度)进行相关分析表明,在近半个世纪内二者存在明显的响应分异,且这种分异在统计上非常显著。此外,这种响应分异多出现在包含低频信号的标准年表里,而在高频信号上几乎没有。在空间上各样点树木的响应分异偏正的组所占总样本量的百分比主要表现为东部高,西部低。垂直高度上,海拔越高树木出现响应分异的也相应越强。
本文得到了与大部分关于分异问题研究相反的结论:在全球变暖的背景下,祁连山青海云杉对温度的敏感性,不但没有减弱反而是增强了。即随着温度的升高,树木生长与温度的联系更加密切。同时,不同响应组的树木与温度之间不论是负相关还是正相关,在时间上都呈增强的趋势。结果还显示,若我们在研究中忽略了样点内树木与温度的响应分异,那么树木对气候要素的敏感性将会被低估。
对区域内各样点树木的生长分异现象进行比较,结果表明随着温度升高,在近三十年里约有71%的树木生长趋势变缓,仅29%的树木生长速度加快。结合研究区水热分布特征,以及垂直梯度上树木与气候要素的关系可知:随着全区气温变暖,在水分较充沛地区的树木更多会表现出与温度的正相关关系;而对于生长在偏干旱区域的树木,则更多的表现为负相关,这就意味着温度升高引起的干旱胁迫对这些树木的影响会日趋严重。因此,20 世纪后期的升温对祁连山上限和近上限的青海云杉之生长可能会带来不利的影响。
青海云杉对近期温度变化的响应不稳定和响应分异在祁连山多数样点均有发现。区域树木的响应变化和响应分异主要发生在20 世纪80 年代以后。其地域分布特点表现为:东部样点树木与温度的正相关关系不断增强,样点内出现响应分异的树木所占比例较高;而西部样点的树木与温度存在负相关关系,且不断增强,发生响应分异的树木在样点内的比例不高。在垂直高度上,海拔越高的树木受温度限制越强,响应分异就越明显。因此,在以后的树轮气候学研究中,我们必须考虑所选样点的树木在20 世纪末期是否出现了分异问题,否则研究结果很有可能会不准确或出现明显错误。
干旱胁迫可能是近半个世纪以来影响祁连山青海云杉响应不稳定的一个重要因素。分析表明,去趋势方法、树龄等因素对于祁连山各样点内的响应分异影响不大。而立地条件的变化、森林干扰等对区域树木的响应变化却有很大影响。树木与温度之间的阈值效应可能会是解释区域树木响应分异现象的潜在原因之一。

Other Abstract

Since the limit of the length of climate record, it is not easy to understand the
mechanism of the climate change. The paleo-climate proxies become the most important
method of current climate research to overcome this shortness. Tree ring data have been
widely used to reconstruct the variability of many climate factors (e.g., temperature,
precipitation), due to their annual resolution, wide spatial distribution, and the possibility
of using simple linear models of climate–tree growth relationships that seem to be easily
verified and calibrated. The stable relationship between tree ring and climate factors is
the fundamental base of dendroclimatology. The rapid global temperature increasing has
caused lot of environmental problems and climatic disasters during last half of 20th
century. More and more investigations displayed that trees growing in high latitude of
northern hemisphere and circle-polar area lost their sensitivity to growth season
temperature that was the main limit factor of tree growth in those area. The relationship
between tree growth and climate factors has been reduced, and even changed. In China,
tree ring also plays an important role in past climate researches. What will happen on tree
have been widely used in China during last half century? In order to investigate this
question, here we study the relationship between tree ring-climate during last half 20th
century in Qilian Mts area where is really sensitive to climate change by using the
regionally dominating tree Qinghai spruce (Picea crassifolia).
In total, we used 342 Qinghai spruces trees which were sampled from 11spatial sites
at upper tree line and 7 different elevation sites along two different slopes. Basing on this
dataset, we discussed the relationship between tree growth and climate factor. The
correlation relationships between every single tree and main climate factors have changed
over time. Within a site, trees had consistent correlations with monthly precipitation, but
the relationships decreased over time. The relationships between trees and monthly
temperature, especially in growth season, had obvious response divergence, which means
within those sites, the consistent relationship between trees and monthly temperature has
been broken. Trees showed different response to monthly temperature as negative
responder and positive responder.
According to different response between trees and monthly temperature, trees of
each site could be clustered into different responder groups as positive responder and
negative responder. The chronologies based on different response groups show same
response divergence with monthly temperature especially in growth season. Most sites
have this response divergence. The response divergences mainly show in STD
chronologies which include mainly low frequency signal. There is almost none response
divergence in RES chronologies which indicate high frequency signal. The percentage of
positive responder within site has a spatial difference. In east Qilian Mts, more sites have
high percentage of positive responder. This percentage deceases at western part of
mountains.
On contrary of the most conclusions about tree growth-climate response around the
world, Qinghai spruces in Qilian Mts show increasing sensitivity to monthly temperature.
As global warming, the relationship between spruce and monthly temperature especially
in growth season become intensive. The correlation relationships, no matter negative
correlation and positive correlation, were getting stronger over time. However, if we
ignore the response divergence within site, the sensitivity between Qinghai Spruce and
monthly temperature will be underestimated.
Comparing the growth divergence within site, it shows that about 71% Qinghai
Spruce had growth reduce, only 29% trees have an increasing growth trend during last
thirty years. Considering the regional hydrothermal and topographical condition, it is
clear to see that trees growing at site that have enough moisture tender to have positive
correlation with monthly temperature, but trees growing at sites in drought area show
more negative response with monthly temperature. Temperature induced drought stress
affect most trees growth than before since circumstance warming. The different response
of trees under different hydrothermal and topographical condition indicate that the
increasing warming during last half century might be harmful for Qinghai spruce,
especially at and near tree line.
The instable relationship between Qinghai spruce and temperature and response
divergence phenomena exist at most sites in Qilian Mts. It happened around 1980. At
spatial scale, trees growing at east Qilian Mts. had increasing positive correlation with
temperature and the ratio of response divergence also increased, trees from west Qilian
Mts. had stronger negative correlation with temperature and low ratio of response
divergence. Sites at the high elevation have the high ratio of response divergence. If we
do not consider the instable relationship between trees and climate factor and ignore the
response divergence within site, the dendroclimatological analysis might be wrong.
Therefore, in future, it is necessary to consider the relationships between tree growth and
climate factors, especially during the end of last century.
At the end of last half century, Qinghai spruce was limited mainly by the
temperature induced drought stress, which also might be reason for the changing
response between trees and monthly temperature. There is no obvious affect on response
divergence from detrending methods and tree age etc.. The standing changing and forest
disturbance have strong influence on response divergence. The threshold between tree
growth and temperature might be the one of the potential reason of response divergence.

Department环境变化与地表过程重点实验室
Subject Area自然地理学
MOST Discipline Catalogue理学::地理学
Table of Contents

第一章 绪 论 ..................................................................................................................................... 1
第一节立论依据及研究意义 .................................................................................................. 1
第二节树木年轮在气候变化研究中的作用及存在的问题 .................................................. 3
1.2.1 树轮气候学在过去气候变化研究中的应用 .......................................................... 3
1.2.2 树轮气候学在过去气候变化重建中的不足和限制 .............................................. 4
1.2.3 树轮资料与气候因子之间响应关系的分异问题 .................................................. 5
第三节研究内容与方法 .......................................................................................................... 8
1.3.1 研究内容 .................................................................................................................. 9
1.3.2 研究方法 .................................................................................................................. 9
第二章祁连山自然地理环境及资料采集 ................................................................................... 10
第一节祁连山自然地理概况 ................................................................................................ 10
2.1.1 气候概况 ................................................................................................................ 11
2.1.2 土壤状况 ................................................................................................................ 12
2.1.3 植被 ........................................................................................................................ 12
第二节青海云杉的生理学特性及其在祁连山的分布 ........................................................ 13
第三节样品的采集及前处理 ............................................................................................... 15
第四节祁连山的历史气候及气象资料收集 ........................................................................ 17
第五节小 结 .......................................................................................................................... 20
第三章祁连山的气候特点及其变化特征 .................................................................................... 21
第一节祁连山气候概况 ........................................................................................................ 21
第二节祁连山气候分区 ........................................................................................................ 23
第三节祁连山气候的周期和突变分析 ................................................................................ 25
3.3.1 周期分析 ................................................................................................................ 25
3.3.2 突变分析 ................................................................................................................ 29
第四节祁连山近百年来的极端气候事件 ............................................................................ 30
第五节小 结 .......................................................................................................................... 31
第四章水平方向分布的树木之径向生长(轮宽)对气候变化的响应 .................................... 33
第一节单株树木对主要气候因子的响应分析 .................................................................... 33
第二节各样点年表的建立及其与温度的分段相关 ............................................................ 41
4.2.1 水平方向各样点的年表及子年表的统计特征 .................................................... 42
4.2.1 水平方向上各年表及其与温度的响应关系 ........................................................ 43
第三节响应分异的水平分布 ................................................................................................ 53
第四节小 结 ......................................................................................................................... 54
第五章不同海拔高度上的树木之径向生长(轮宽)对气候变化的响应 ................................ 56
第一节单株树木对主要气候因子的响应分析 .................................................................... 56
第二节不同梯度的样点年表的建立及其与温度的分段相关 ............................................ 62
第三节响应分异的垂直分布 ................................................................................................ 71
第四节小 结 ........................................................................................................................... 72
第六章青海云杉对气象要素响应的时空差异 ............................................................................ 74
第一节区域气象要素与青海云杉响应及分异关系 ........................................................... 74
6.1.1 水平分布的青海云杉之响应分异及其与所在小区的关系 ................................ 75
6.1.2 水平方向不同样点海拔高度的影响 .................................................................... 76
6.1.3 响应分异和区域气候信号之间的关系 ................................................................ 77
第二节不同高度上的气候因子与树木的响应及分异关系 ................................................ 81
6.2.1 不同海拔高度对树木与气候因子关系的影响 .................................................... 81
第三节小 结 ........................................................................................................................... 85
第七章讨论 I: 祁连山区青海云杉与气候要素响应及分异的对比分析 .................................... 87
第一节祁连山青海云杉对气候因子响应的敏感性问题 .................................................... 87
第二节祁连山青海云杉的生长及分异问题 ........................................................................ 88
第三节青海云杉的响应分异对利用树轮重建气候的影响 ................................................ 92
第四节小 结 ........................................................................................................................... 94
第八章讨论 II:祁连山青海云杉响应分异的潜在原因分析 .................................................... 96
第一节干旱胁迫对树木响应变化的影响 ............................................................................ 97
第二节数学方法对树木-气候因子关系的影响 ................................................................... 99
8.2.1 树轮资料的标准化及尾端效应对响应分异的影响 ............................................ 99
第三节非气候要素对各样点内响应分异的影响 .............................................................. 103
8.3.1 立地变化对响应分异的影响 .............................................................................. 103
8.3.2 森林干扰对响应分异的影响 .............................................................................. 105
第四节树木生理机制对响应分异的可能影响 .................................................................. 107
8.4.1 树龄结构与生长速度 .......................................................................................... 107
8.4.2 阈值效应 .............................................................................................................. 110
第五节小 结 ......................................................................................................................... 112
第九章结论和展望 ...................................................................................................................... 115
第一节结 论 ......................................................................................................................... 115
第二节展 望 ......................................................................................................................... 116
附录 .............................................................................................................................................. 118
参考文献....................................................................................................................................... 131
个人 简 历 .................................................................................................................................... 143
后记…… ............................................................................................................................... 144

Pages144页
URL查看原文
Language中文
Document Type学位论文
Identifierhttp://ir.itpcas.ac.cn/handle/131C11/8461
Collection图书馆
Recommended Citation
GB/T 7714
张永香. 祁连山青海云杉对20 世纪50 年代以来 气候变化的响应分析[D]. 北京. 中国科学院研究生院,2009.
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