长白山红松和鱼鳞云杉在分布上限的径向生长对气候变暖的不同响应

用树木年代学方法研究了近50年来气候变化对长白山自然保护区两种广泛分布的重要乔木树种红松(Pinus koraiensis)和鱼鳞云杉(Picea jezoensis var. komarovii)分布上限树木径向生长的影响, 发现红松年轮宽度具有与温度升高相一致的趋势, 而鱼鳞云杉年轮宽度则出现随温度升高而下降的“分离现象”。对水热条件的正响应是分布上限红松年表与温度保持一致的关键: 生长季的温度和降水的增加对上限红松的生长有促进作用, 且二者对树木生长的有利效应有相互促进的现象; 生长季的延长也有利于红松的生长。升温导致的水分胁迫是造成上限分布的鱼鳞云杉年轮宽度与温度变化趋势相反的重要因素: 分布上限的鱼鳞云杉年表与大多数温度指标均呈负相关关系; 随着温度升高, 年表与年降水量尤其是春季降水量的相关性逐渐由负转正; 各月的高温以及生长季中后期的少雨是形成上限鱼鳞云杉窄轮的主要气候因素, 而较低的各月温度以及生长季后期充足的降水则有利于上限鱼鳞云杉的生长; 此外, 生长季长度没有变化也可能是造成鱼鳞云杉年表序列对温度变化敏感性下降的重要因素。     

天山东部西伯利亚落叶松树轮生长对气候要素的响应分析

天山东部西伯利亚落叶松的树木年轮学研究可以看出：森林上限树轮宽度年表之间相关性较高而下限年表间相关稍低,表明下限小生境要素对树木生长干扰较大。森林上下限树轮年表中样本的总解释量（ESP）和信噪比（SNR）都比较高,说明树木中都含有较多的环境信息;但标准年表中平均敏感度（M．S．）和轮宽指数的标准差（S．D．）都是森林上限数值低于下限,这表明森林上限树木生长对环境变化响应的敏感性降低;相关分析和响应分析也发现森林下限生长的树木对气候因子的响应较为显著。就温度而言,森林上限和下限表现基本一致,树木生长多与温度负相关,其中下限树木生长与春季均温和3．6月份均温显著负相关;降水表现出一定的差别,上限树木生长与春季、夏季及年降水量有较高的负相关,而对下限树木生长影响最大的则是冬季和3—6月份降水。湿润指数与降水基本一致即上限呈负相关而下限正相关,温暖指数全为负相关,寒冷指数下限负相关显著;显然该地区森林上下限树木生长的生态模式存在着一定的差异。研究发现,冬春季节的不同水热组合则是形成树木年轮宽窄的限制因素;同时,前期生长的滞后效应对年轮形成有重要的影响。     

川西米亚罗林区不同海拔岷江冷杉生长对气候变化的响应

为分析青藏高原东缘半湿润区树木生长与气候关系随海拔变化的规律,于川西米亚罗林区分别在高、中、低海拔选取3个采样点,共采集132棵岷江冷杉年轮样芯,建立了最长达170a(1842-2011年)3个海拔高度的差值年表.岷江冷杉年轮指数与气候因子的相关分析表明:随海拔高度降低,温度与生长的负相关呈增加趋势.高海拔岷江冷杉径向生长与前—年冬季最低温呈显著正相关,中低海拔与当年春季均温、最高温和年均最高温呈显著负相关.低海拔岷江冷杉与当年4月降水呈显著正相关,随海拔升高降水与岷江冷杉生长的相关性降低.中低海拔岷江冷杉年表与4、5月帕尔默干旱指数(P DSI)呈显著正相关,表明在中低海拔存在春季干旱胁迫,抑制了岷江冷杉的生长.另外,大龄树木比小龄树木对气候变化的响应更敏感.     

天山东部不同海拔西伯利亚落叶松对气候变暖的响应分析

利用树木年轮气候学方法,探讨了在气候变暖情景下,天山东部上中下限西伯利亚落叶松（Larix sibirica）树木径向生长与气候因子之间的响应关系,并利用冗余分析对其关系进行了验证。结果表明：不同海拔的差值年表（RES）要比标准年表（STD）的特征参数大,具有更高的信噪比和平均敏感度,含有较多的环境信息且更能代表树木总体变化;海拔2160m处的年表（L1）在快速升温（1985年）后,树木年轮宽度与降水和温度的相关性明显减弱;海拔2430m处的年表（L2）在两个时段内与降水和温度的关系均较弱;海拔2700m处的年表（L3）在1985~2013年时段内对降水和气温的正响应均增强。树木径向生长对单月气候因子的响应在前一年11、12月份显著性更高,当年6、7月份气温与树轮宽度指数具有更高的相关性。气候变暖使树木径向生长不断减小的特征在低海拔地区表现更为明显。上中下限西伯利亚落叶松对气温升高的敏感性降低。高海拔地区西伯利亚落叶松的径向生长主要受温度的影响,而中低海拔地区主要受降水与温度的共同影响。     

玉龙雪山不同海拔丽江云杉径向生长对气候变异的响应

为研究滇西北高原树木径向生长与气候关系随海拔的变化规律, 分别在玉龙雪山低、中、高海拔采集丽江云杉(Picea likiangensis)年轮样本, 建立了不同海拔丽江云杉树轮宽度残差年表, 将年轮指数与气候因子进行响应分析、冗余分析以及滑动响应分析。结果表明: 玉龙雪山丽江云杉径向生长受气温和降水共同影响, 但不同海拔径向生长响应模式存在差异。其中当年1-3月降水与不同海拔丽江云杉径向生长均呈显著正相关关系; 当年生长季后期降水与中、低海拔树木生长呈显著负相关关系, 与高海拔树木生长呈显著正相关关系; 中、低海拔树木生长还受当年春季干旱胁迫; 而当年7月气温升高促进高海拔丽江云杉生长。冗余分析与响应分析结果基本一致, 说明冗余分析能够有效量化树轮宽度指数与气候因子的关系。滑动响应分析显示气温和降水在小时间尺度上的变化也会影响树木生长。结合不同海拔丽江云杉生长对气候因子的响应模式及未来气候预测, 玉龙雪山高海拔丽江云杉生长将得到加强, 而中、低海拔丽江云杉生长则表现出不确定性。     

Radial growth responses of Picea likiangensis to climate variabilities at different altitudes in Yulong Snow Mountain,southwest China

为研究滇西北高原树木径向生长与气候关系随海拔的变化规律, 分别在玉龙雪山低、中、高海拔采集丽江云杉(Picea likiangensis)年轮样本, 建立了不同海拔丽江云杉树轮宽度残差年表, 将年轮指数与气候因子进行响应分析、冗余分析以及滑动响应分析。结果表明: 玉龙雪山丽江云杉径向生长受气温和降水共同影响, 但不同海拔径向生长响应模式存在差异。其中当年1-3月降水与不同海拔丽江云杉径向生长均呈显著正相关关系; 当年生长季后期降水与中、低海拔树木生长呈显著负相关关系, 与高海拔树木生长呈显著正相关关系; 中、低海拔树木生长还受当年春季干旱胁迫; 而当年7月气温升高促进高海拔丽江云杉生长。冗余分析与响应分析结果基本一致, 说明冗余分析能够有效量化树轮宽度指数与气候因子的关系。滑动响应分析显示气温和降水在小时间尺度上的变化也会影响树木生长。结合不同海拔丽江云杉生长对气候因子的响应模式及未来气候预测, 玉龙雪山高海拔丽江云杉生长将得到加强, 而中、低海拔丽江云杉生长则表现出不确定性。     

长白山不同海拔树木生长对气候变化的响应差异

以长白落叶松和红松为例,探讨了长白山地区不同海拔树木生长对气候变化的响应。利用长白山北坡不同海拔4个长白落叶松样点和6个红松样点的树轮宽度资料建立差值年表,通过聚类分析、相关分析和响应分析等方法,研究树木生长特征及其气候响应。结果表明:两个树种年表的平均敏感度、树轮宽度指数的年际变率、信噪比等特征值较高,反映年表含有较强的环境信息。随海拔升高,长白落叶松年表特征值呈先下降后增加的趋势,红松年表特征值则呈先增加后下降的趋势。聚类分析将长白落叶松年表分成高、低海拔两类,红松年表分成高、中、低海拔三类。树木生长对气候响应存在海拔差异。高海拔长白落叶松生长受当年气温影响;低海拔长白落叶松生长对气候存在"滞后响应"。高海拔红松不仅受降水限制,且对气温有"滞后响应";中海拔红松不仅受气温限制,且对降水有"滞后响应";低海拔红松生长主要受气温限制。     

昌岭山两个优势树种径向生长对气候变化的响应

在气候变暖背景下,树木径向生长对气候变化的响应存在不稳定性。利用采自祁连山东部余脉昌岭山两个优势树种油松和青海云杉的树轮样芯,建立树轮宽度标准年表,通过分析树轮宽度年表与气候要素的相关关系,探讨两个树种径向生长对气候变化的响应。结果表明：（1）油松年表比青海云杉年表包含更多的气候信息,其平均敏感度、标准差、信噪比和样本对总体的代表性等统计量均高于青海云杉标准年表。（2）气候要素对不同树种径向生长限制程度不同,油松径向生长主要与降水（前一年9月和当年3-8月）和气温（前一年9月）有关,但对降水的响应更为敏感,而青海云杉径向生长则受到气温（当年9月）和降水（前一年9月、当年3月和7月）的共同作用。（3）气温突变后,油松和青海云杉年表与各气温要素的相关性显著增强,而青海云杉年表与气温要素的相关性变化更明显,指示了青海云杉径向生长对气温的响应更不稳定。（4）生长季平均最低气温的升高诱导的干旱胁迫是油松和青海云杉树木径向生长-气温响应变化的主要原因。     

阿尼玛卿山地不同海拔青海云杉(Picea crassifolia)树轮生长特性及其对气候的响应

利用位于同一坡面的青海云杉树芯样本,建立了4个海拔高度的树轮宽度指数年表。分析结果表明年表序列特征值大都因海拔而不同,各年表序列对气候因子的相关性在不同高度也表现出一定的差异:树木生长都与前一年10月份月均温显著正相关,与前一年8月份和当年5、6月份月均温显著负相关;与前一年9、10月份和当年5月份的降水量都呈显著正相关,但都随海拔升高呈波状变化。树轮宽度指数与不同时段的温度和温暖指数都呈负相关,表明5～9月是该地区青海云杉生长较为活跃的季节。响应函数分析结果表明该地区低海拔生长的青海云杉受温度和降水的影响都比高海拔生长的更显著,显然不同于以前研究的森林上下限树木的生长模式。4a表主成分中的第一主分量贡献率为81.071%,表明同一坡面影响树木生长的大环境因子是一致的。第一主分量与气候因子的相关分析同样显示出前一年生长季末和当年生长季初的水热组合是树木生长的主要限制因子,区域模拟也进一步证明了这一点。并认清了同一坡面青海云杉树轮记录的共性和差异,为今后树轮采样和研究提供一定的理论依据。     

阿尼玛卿山地不同海拔青海云杉(Picea crassifolia)树轮生长特性及其对气候的响应

利用位于同一坡面的青海云杉树芯样本,建立了4个海拔高度的树轮宽度指数年表。分析结果表明年表序列特征值大都因海拔而不同,各年表序列对气候因子的相关性在不同高度也表现出一定的差异：树木生长都与前一年10月份月均温显著正相关,与前一年8月份和当年5、6月份月均温显著负相关;与前一年9、10月份和当年5月份的降水量都呈显著正相关,但都随海拔升高呈波状变化。树轮宽度指数与不同时段的温度和温暖指数都呈负相关,表明5～9月是该地区青海云杉生长较为活跃的季节。响应函数分析结果表明该地区低海拔生长的青海云杉受温度和降水的影响都比高海拔生长的更显著,显然不同于以前研究的森林上下限树木的生长模式。4 a表主成分中的第一主分量贡献率为81.071%,表明同一坡面影响树木生长的大环境因子是一致的。第一主分量与气候因子的相关分析同样显示出前一年生长季末和当年生长季初的水热组合是树木生长的主要限制因子,区域模拟也进一步证明了这一点。并认清了同一坡面青海云杉树轮记录的共性和差异,为今后树轮采样和研究提供一定的理论依据。     

Climatic signals in tree ring of Picea schrenkiana along an altitudinal gradient in the central Tianshan Mountains, northwestern China

Tree-ring samples of Picea schrenkiana (Fisch. et Mey) were studied along an altitudinal gradient in the central Tianshan Mountains, and ring-width chronologies were developed for three sites at different altitudes: low-forest border (1600–1700 m a.s.l.), interior forest (2100–2200 m a.s.l.), and upper treeline (2600–2700 m a.s.l.). Annual ring-width variations were similar among the three sites but variability was greatest at the low-forest border site. The statistical characters of the chronologies showed that mean sensitivity (MS) and standard deviation (SD) decreased with increasing elevation. In other words, the response of tree growth to environmental changes decreased with increasing altitude. To understand the differing response of trees at different elevations to the environmental changes, response function analysis was used to study the relationships between tree-ring widths and mean monthly temperature and total monthly precipitation from 1961 to 2000. The results showed that precipitation was the most important factor limiting tree radial growth in the arid central Tianshan Mountains, precipitation in August of the prior growth year played an important role on tree's radial growth across the entire altitudinal gradient even at the cold, high-elevation treeline site. It is expected that with increasing altitude air temperature decreased and precipitation increased, the importance of precipitation on tree growth decreased, and the response of tree growth to environmental changes decreased, too. This conclusion may be helpful to understand and research the relationship between climatic change and tree growth in arid and semiarid area.     

不同去趋势方法的新疆东天山高低海拔雪岭云杉树轮宽度年表对气候的响应

利用新疆东天山高低海拔雪岭云杉(Picea schrenkiana Fisch.et Mey.)年轮样本,采用样条函数法、负指数函数法和区域曲线法3种去趋势方法研制树轮宽度标准化年表,通过分析不同去趋势方法的新疆东天山高低海拔云杉树轮宽度标准化年表特征、年表与气候响应的关系和年表间在不同频域互相关,及其与其它资料对比发现:(1)3种去趋势法对东天山年表质量影响较小,低海拔树轮年表含有更多可靠的气候变化信息。(2)高海拔的雪岭云杉树木径向生长与6—9月平均气温均呈显著正相关,其中标准化树轮年表与7月平均气温相关系数达0.553(P0.01,n=58),夏季温度可能是东天山高海拔雪岭云杉径向生长的主要限制因子;低海拔雪岭云杉树木径向生长与春季降水显著正相关,同时与春季平均气温显著负相关,春季高温和缺水共同作用的春旱可能是影响低海拔雪岭云杉径向生长的主导因子,且负指数函数年表对气候响应更敏感。(3)区域曲线法能够保留树轮标准化年表中更多低频信息,但优势不明显。高低海拔标准化年表在低频域相关系数较大,并和历史干旱事件有很好的对应。在东天山高低海拔雪岭云杉的去趋势方法研究中,负指数函数法比样条函数法和区域曲线法更适合。     

Climate Control on Tree Growth at the Upper and Lower Treelines: A Case Study in the Qilian Mountains,Tibetan Plateau

It is generally hypothesized that tree growth at the upper treeline is normally controlled by temperature while that at the lower treeline is precipitation limited. However, uniform patterns of inter-annual ring-width variations along altitudinal gradients are also observed in some situations. How changing elevation influences tree growth in the cold and arid Qilian Mountains, on the northeastern Tibetan Plateau, is of considerable interest because of the sensitivity of the region’s local climate to different atmospheric circulation patterns. Here, a network of four Qilian juniper (Sabina przewalskii Kom.) ring-width chronologies was developed from trees distributed on a typical mountain slope at elevations ranging from 3000 to 3520 m above sea level (a.s.l.). The statistical characteristics of the four tree-ring chronologies show no significant correlation with increasing elevation. All the sampled tree growth was controlled by a common climatic signal (local precipitation) across the investigated altitudinal gradient (520 m). During the common reliable period, covering the past 450 years, the four chronologies have exhibited coherent growth patterns in both the high- and low-frequency domains. These results contradict the notion of contrasting climate growth controls at higher and lower elevations, and specifically the assumption that inter-annual tree-growth variability is controlled by temperature at the upper treeline. It should be stressed that these results relate to the relatively arid conditions at the sampling sites in the Qilian Mountains.     

Individual and time-varying tree-ring growth to climate sensitivity of Pinus tabuliformis Carr. and Sabina przewalskii Kom. in the eastern Qilian Mountains, China

Individual tree-ring width chronologies and mean chronologies from Pinus tabuliformis Carr. (Chinese pine) and Sabina przewalskii Kom. (Qilian juniper) tree cores were collected and analyzed from two sites in the eastern Qilian Mountains of China. The chronologies were used to analyze individual and time-varying tree-ring growth to climate sensitivity with monthly mean air temperature and total precipitation data for the period 1958–2008. Climate–growth relationships were assessed with correlation functions and their stationarity and consistency over time were measured using moving correlation analysis. Individuals’ growth–climate correlations suggested increased percentages of individuals are correlated with certain variables (e.g., current June temperature at the P. tabuliformis site; previous June, December and current May temperature and May precipitation at the S. przewalskii site). These same climatic variables also correspond to the mean chronology correlations. A decreased percentage of individuals correlated with these climatic variables indicates a reduced sensitivity of the mean chronology. Moving correlation analysis indicated a significant change over time in the sensitivity of trees to climatic variability. Our results suggested: (1) that individual tree analysis might be a worthwhile tool to improve the quality and reliability of the climate signal from tree-ring series for dendroclimatology research; and (2) time-dependent fluctuations of climate growth relationships should be taken into account when assessing the quality and reliability of reconstructed climate signals.     

Climatic response of three tree species growing at different elevations in the Lüliang Mountains of Northern China

In this study, we present the results of a dendroclimatological investigation of three coniferous tree species, Larix principis-rupprechtii, Picea meyeri and Pinus tabulaeformis, growing along an altitudinal gradient at the Lüliang Mountains in Northern China. Totally five tree-ring width chronologies were developed to explore the climate-growth responses of these tree species. No obviously regular trend associated with the increase of elevation was found by comparing the statistical characteristics of the chronologies. Correlation analysis indicated that the chronologies from lowerest to middle-high sites (SZ, BWD, BDGL and BDGP, respectively) were highly correlated, and different species from the same site showed the highest correlation. Growth–climate analysis indicated that the chronology of Larix principis-rupprechti at the uppermost site near the tree line (XWS) did not exhibit a significant response to the seasonal climatic factors, whereas the other four lower chronologies were consistently and significantly influenced by both the mean temperature from May to July and the total precipitation from March to June, regardless of tree species and elevation. The similarity of the tree growth–climate relationships of different species growing at different elevations (except that from the tree line) suggests that the trees in this region can provide common regional climate information, and combinations of multiple species (RC) are more successful in reconstructing the climate data than single species. The results of this research are very crucial for the future forest management and dendroclimatological sampling strategy in the arid to semi-arid area of northern China.     

1998—2017年祁连山南坡不同海拔、坡度和坡向生长季NDVI变化及其与气象因子的关系

祁连山是我国西北地区重要的水源涵养保护区,是我国地形第一、二阶梯分界线,对气候变化极其敏感。基于气温、降水量和归一化植被指数(NDVI)数据,使用趋势分析、小波分析和相关分析方法,结合数字高程模型(DEM)数据,从海拔、坡度和坡向的角度探讨祁连山南坡NDVI变化及其与气温和降水的关系。结果表明: 1998—2017年,祁连山南坡生长季NDVI整体呈增长趋势,增长趋势为0.023·10 a^-1。NDVI值在不同海拔、坡度和坡向上的变化存在差异性,NDVI值随海拔的升高呈先增后降趋势,海拔2700～3700 m区域的植被覆盖状况较好,＞4700 m区域的植被出现退化现象;NDVI值随坡度增加呈降低态势;NDVI值在坡向上的差异较小,但阳坡的植被覆盖状况好于阴坡。生长季NDVI与气温、降水的关系密切,生长季NDVI、气温、降水均具有14年的变化周期,而不同海拔、坡度、坡向的植被受到气温和降水的影响不同,海拔＜3700 m、＞4700 m区域、坡度＜25°区域和各坡向区域的植被均易受降水影响。     

Different trends and divergent responses to climate factors in the radial growth of Abies georgei along elevations in the central Hengduan Mountains

Climate change has been unprecedented in the last half-century. Tree growth dynamics and responses to climate warming at different elevations vary by study area due to regional diversity in site-specific climatic conditions in the central Hengduan Mountains. A. georgei is the dominant species in high-elevation montane forests in the central Hengduan Mountains. To study the response of A. georgei radial growth to climate and identify tree growth trends at different elevations, tree-ring width chronologies at four elevations across the subalpine A. georgei forest belt were built and growth-climate relationships were analyzed. The primary findings of this study were as follows: (1) radial growth rates of A. georgei decreased with elevation; (2) warming alleviated the limitation of low temperatures and abundant precipitation on tree radial growth at the highest sampling site; and (3) unlike at other elevations, the trend of trees basal area increment (BAI) at the lowest sampling site showed a significant decline over the past 20 years. This suggests the presence of an elevational inflection point, likely between 3800 m and 4000 m, where tree growth trends diverge. These results confirmed that A. georgei at higher elevation in the central Hengduan Mountains currently benefits from higher temperatures. However, the effects of drought on A. georgei at lower elevations would cause radial growth to decrease with climate warming. Therefore, it is critical to establish effective management strategies based on how A. georgei responds to climate change at various elevations.     

芦芽山华北落叶松(Larix principis-rupprechtii)树轮宽度年表对气候因子的响应

在芦芽山地区采集3个不同海拔的华北落叶松(Larix principis-rupprechtii),在传统去趋势的基础上,采用"signal-free"方法对拟合曲线进行修正,避免了中等频率的气候信息引起的拟合偏差,最终建立3个不同海拔树轮宽度标准年表(STD)。同时以10a为界对上述年表进行滤波处理,得到3个低频年表。年表特征值表明,随着海拔升高,年轮平均轮宽变窄,敏感性和高频信息增强,低频信息减弱,这可能与逐渐恶劣的生境有关。中、低海拔年表的低频信息更一致,中、高海拔的高频信息更接近,而高、低海拔无论是标准年表还是高频、低频年表相似性均较差。树轮气候响应分析显示,低海拔STD年表与5月最低温负相关最为显著,STD和低频年表均与5、6月份土壤温度显著负相关,说明生境暖干,树木主要受生长季的干旱胁迫;中海拔STD年表与当年5月最高温正相关最为显著,STD和低频年表与土壤温度相关均不显著,说明生境逐渐变得冷湿,生长季的低温成为树木生长的限制因子;高海拔STD年表与气象要素相关不显著,低频年表与当年4月土壤温度正相关,说明高海拔最为冷湿,并有季节性冻土分布,生长季的土壤低温成为树木生长的限制因子。因此,全球变暖的趋势将更有利于高海拔树木的生长,而低海拔树木的干旱胁迫进一步加剧。     

不同生境和去趋势方法下的祁连圆柏径向生长对气候的响应

利用青海不同生境祁连圆柏树木年轮样本,采用3种不同去趋势方法建立树轮年表,结合青海30个气象站的气象资料,分析不同生境和去趋势方法下祁连圆柏径向生长对气候的响应差异。结果表明,祁连山区,生长季前期的平均气温是祁连圆柏树木径向生长的主要限制性因子,NEP树轮标准化宽度年表与生长季前期冬季平均气温相关最好;在柴达木盆地,生长季降水量是该地区树木径向生长的限制性因子,SPL树轮年表对生长季降水量相关较好;在青南高原,祁连圆柏径向生长对春季温度响应最为敏感,而SPL年表与春季温度呈现明显的负相关关系,相关系数达-0.606;而在青海东部地区,祁连圆柏树木径向生长对气候的响应总体不显著。位于青海西部和北部的柴达木盆地和祁连山区祁连圆柏径向生长受西风气候的影响显著,尤其是柴达木盆地,其气候受西风主导;而青南高原受西南季风影响更为显著,该地区祁连圆柏径向生长同时受西南季风气候和海拔高度两方面影响;在青海东部,祁连圆柏径向生长受东亚季风影响更为显著。