中国科学院新疆生态与地理研究所机构知识库

近半个世纪以来，在全球气温不断升高的背景下，全球极端干旱区域的面积扩大了两倍以上，部分地区干湿状况严重失衡，严重影响了地区经济和社会发展。天山山脉作为我国重要的地理单元，其自然地理变化对区域生态环境有重要的影响，因此研究其干湿变化具有重要的意义。本文采用树木年代学、相关性分析、功率谱分析、周期分析、线性回归分析等方法研究了天山东中西部地区雪岭云杉（Schrenk Spruce）在不同去趋势方法下记录的天山东中西部的干湿状况变化及与大尺度气候因子之间的关系。主要结论如下：（1）天山西中东部地区不同去趋势方法建立的年表的相关系数（R1、 R2、R3）值、第一主成分（PC1）均较高，说明年表质量较好，含有较多的环境信息，样本对总体的信号解释量（EPS）分别达到 0.992-0.993、 0.968-0.972 和0.977-0.981 均超过了 0.85 的最低阈值，说明此次研究所建立的不同去趋势的年表都是研究气候响应的可信资料，数据采样较成功，采样点树轮资料中含有可靠的气候信号，可进一步用于树轮气候学的分析。（2） 不同年表保留不同频率信息的能力存在较大的差别。 天山东中西部轮宽指数功率谱分析表明 10 年步长的样条函数（SPL10）去趋势方法建立的年表在揭示低频信息变化上优势明显，负指数函数（NEP）、区域曲线法（RCS）、 300年步长的样条函数（SPL300）和 120 年步长的样条函数（SPL120）去趋势方法建立的年表在揭示高频信息变化上更有优势。天山东中西部都存在 50a 的长周期，以及 2a-6a 的短周期。（3）天山西部除了 SPL10 年表和 SPL300 年表，剩下的五种去趋势方法得到的年表对降水的响应差异不大，表现为与前一年 11 月、当年 4 月和当年 5 月降水显著正相关（P<0.05），与当年 9 月降水显著负相关；天山中部地区不同去趋势方法建立年表与气候因子的关系主要表现在与上一年 9 月、当年 5、 6、 7 月降水显著正相关，与当年 5、 6、 7 月均温和高温显著负相关；天山东部地区在NEP 和 RCS 去趋势方法下得到的轮宽指数与上一年 10 月份和 11 月份的降水显著正相关，气温对树木生长的影响以负相关为主，达到显著性水平的年表有NEP、 RCS 和 SPL300 去趋势方法建立的年表。（4）天山西部 SPL300 去趋势方法建立的标准化年表（STD）与标准化降水蒸发指数/标准化降水指数（SPEI/SPI）的显著相关发生在 8-13 个月尺度上的 5-8 月份；天山中部雪岭云杉利用 RCS 建立的年表对不同时间尺度 SPEI/SPI 的响应更显著，与 SPEI 相关性极显著发生在 6-16 个月时间尺度，从 5 月份开始SPEI 的影响一直持续到 12 月份。在 5-24 个月尺度上 SPI 在全年的范围内与轮宽指数均达到极显著正相关。天山东部地区雪岭云杉轮宽指数在短时间尺度（2-7 个月）上 8-12 月份的 SPEI 与轮宽指数均达到了极显著负相关水平，而在长时间尺度（20-24 个月）上 1-7 月份的 SPEI 与轮宽指数达到了显著负相关的水平。在长时间尺度（20-24 个月）上与 1-7 月份的 SPI 的负相关更显著，说明降水对雪岭云杉轮宽指数的负影响在长时间尺度上更明显。天山中西部轮宽指数与 PDSI 均达到显著相关水平，东部地区未达到显著相关水平。（5） 在 天 山 西 中 东 部 地 区 分 别 选 择 了 5-8 月 份 平 均 SPEI11/SPI11、SPEI13/SPI13 和 SPEI24/SPI24 用于干湿状况的重建和分析。重建结果显示天山西部地区在 1870-1880 年、 1960-1985 年 SPEI11/SPI11 值较低，处于干旱期，在1870 年、 1885 年附近、 1930-1940 年以及 1990-2002 年处于湿润期；天山中部地区 1915-1940 年、 1965-1980 年处于干旱期， 1940-1963 年、 1980-2000 年处于湿润期；天山东部地区在 1810-1820 年、 1830-1840 年、 1880-1890 年、 1960-1978 年处于干旱期，其中 1830-1840 年和 1965-1978 年处于较干旱时期， 1800-1803 年、 1850-1880 年、 1920-1940 年和 2010-2015 年天山东部处于湿润期，较显著的湿润期发生在 1855-1863 年和 1925-1935 年。太平洋十年涛动指数（PDO）、北极涛动指数（AO）和北大西洋涛动指数（NAO）均对天山地区干湿变化产生影响。

In the past half century, under the background of global warming, the area of theextreme arid region of the world has expanded more than two times, and even thebalance between the dry and wet in some regions has changed dramatically, whichseriously affects the economic and social development of the regions. As an importantgeographical unit in China, the Tianshan Mountains, whose natural geographicalchange have an important influence on the regional ecological environment, so it is ofgreat significance to study the dry and wet changes in this region. In this paper we usethe tree chronology method to study the changes of dry and wet in the eastern, middleand western Tianshan Mountains in china, which was obtained by analyzing the datarecorded by the Schrenk Spruce in the eastern, middle and western regions ofTianshan Mountains using different detrending methods. In this paper we mainlyanalyzes the contrast of characteristic parameters under different detrending methods,and the differences between the different detrending methods in revealing theinformation of high and low frequency and in the periodic analyzing, and thecorrelativity between the meteorological factors and the Schrenk Spruce in theeastern, middle and western Tianshan Mountains under different detrending methods.Furthermore, on the above basis, in this paper we also discussed the relationshipbetween the tree ring width index of the Schrenk Spruce in Tianshan Mountains andthe index of dry wet (i.e. SPEI, SPI, and PDSI), and we reconstructed the changes ofthe dry and wet condition in the regions of Tianshan Mountains in the past years byusing the tree ring width index and the possible factors that may cause the change ofdry and wet. The main conclusions of this paper are as follows:(1) In the chronology of western， middle and eastern Tianshan Mountains,established by using different detrending methods, the values of the coefficients ofcorrelation (i.e. R1, R2, and R3) and the first principal component (PC1) of thechronology are all high, which indicate that the quality of the chronology is relatively better and the chronology contains more environmental information. The expressedpopulation signal(EPS) respectively up to the level of 0.992-0.993, 0.968-0.972, and0.977-0.981, all of them are higher than the minimum threshold of 0.85, whichindicate that the different detrending chronology established in the paper are reliabledata for the research on the climate response, the data sampling is relativelysatisfactory and the tree ring data of the sampling points contain reliable climaticsignals, which can be further used in the analysis of tree ring climatology.(2) For the different chronologies, there are great differences in the ability ofretaining the information in different frequencies. The power spectrum analysis of thetree ring index in eastern, middle, and western Tianshan Mountains shows that thechronologies established by the detrending method of SPL10 has obvious advantagesin revealing the change of the information in low frequency, while those chronologiesestablished by the other detrending methods such as NEP, RCS, SPL300 and SPL120has more advantages in revealing the change of information in high frequency. For theregions of eastern, middle and western Tianshan Mountains, there all exit long periodsof 50a and short periods of 2a-6a.(3) In addition to the SPL10 chronology and the SPL300 chronology in the westernregions of Tianshan Mountains, the remaining five chronologies established by theother detrending methods have little differences in the response to precipitation,which was shown that there is a significant positive correlation between thechronologies and precipitation in November of the last year, April and May of theyear (P<0.05), and the significant negative correlation in September of the year. Therelationship between the chronologies established by different methods of detrendingin the middle regions of Tianshan Mountains and the climatic factors is mainly relatedto the significant positive correlation with the precipitation in Septembers of last year,in May, June and July of the year, while that is significantly negative correlated withthe average temperature and high temperature in May, June and July of the year. Thetree ring width index in the eastern regions of Tianshan Mountains established by thedetrending method of NEP and RCS is significantly positive correlated with the precipitation in October and November. The effect of temperature on the growth oftrees is mainly negative correlated, in which the NEP, RCS and SPL300 reach thelevel of significantly correlation.(4) The significant correlation between the STD chronology set up by thedetrending method of SPL300 in western Tianshan Mountains and the SPEI/SPIhappened in the time from May to August on a long scale of 8-13 months. Thechronology of Schrenk Spruce in the middle Tianshan Mountains established by themethod of RCS has more significant response to the SPEI/SPI on different timescales, and the correlation with SPEI significantly happened on a time scale of 6-16months, the impact of the SPEI beginning from May and continued until December.On the scale of 5-24 months, the SPI has a very significant positive correlation withthe tree ring width index in the whole range of the year. For the tree ring width indexof Schrenk Spruce in the eastern Tianshan Mountains, on a short time scale (i.e. 2-7months), the SPEI reached a quiet significant negative correlation with the tree ringwidth index during the time from August to December. However on a long time scale(i.e. 20-24 months), the SPEI has a quiet significant negative correlation with the treering width index during the time from January to July, which illustrate that thenegative effects of precipitation on the tree ring width index of Schrenk Spruce ismore obvious on the long time scales. The negative correlation between the long timescale (20-24) months and 1-7 months was more significant, indicating that thenegative effect of precipitation on the round width index of spruce spruce was moreobvious on a long time scale. The relationship between tree ring width index in themidwestern Tianshan Mountains and the PDSI reached a level of significantcorrelation, however, the same relationship in the eastern regions has not reached asignificant correlation level.(5) In the western, middle and eastern Tianshan Mountains, we separately choosethe average SPEI11/SPI11, SPEI13/SPI13 and SPEI24/SPI24 between the monthsfrom May to August to reconstruct and analysis the condition of dry and wet. Thereconstruction results show that in the time during 1870-1880 and the time during 1960-1985, the value of SPEI11/SPI11 in the western regions of Tianshan Mountainsis relatively low, which means the areas are just in the drought periods, while theareas are in the humid periods in 1870, in the vicinity of 1885, in the time during1930-1940 and the time during 1990-2002. The middle regions of TianshanMountains are in drought during the periods of 1915-1940 and 1965-1980, whilethose are in humid periods during the periods of 1940-1963 and 1980-2000. Theeastern regions of Tianshan Mountains are in the drought periods during the time of1810-1820, 1830-1840, 1880-1890, and 1960-1978, of which 1830-1840 and 1965-1978 are in a relatively drought periods, while those are in the humid periods duringthe periods of 1800-1803, 1850-1880, 1920-1940 and 2010-2015, and the relativelysignificant humid periods occurs in the time of 1855-1863 and 1925-1935. The PDO,AO and NAO all have effect on the change of dry and wet in the regions of TianshanMountains.