川西亚高山不同年龄紫果云杉径向生长对气候因子的响应

运用树木年轮气候学的基本方法,建立王朗自然保护区紫果云杉在集中分布上限区域的年轮宽度年表,选取差值年表分析不同年龄云杉的径向生长同逐月气候因子的相关及响应关系,结果显示:幼龄组云杉年表的敏感度高于中龄组和老龄组云杉,幼龄组云杉对生长季前及生长季的气温状况显著正相关;中龄组云杉年表仅与当年4月份和7月份的月平均最低气温显著正相关;老龄组云杉的年轮宽度指数同上年生长季(上年8月份)的月平均气温和月平均最低温显著负相关,上年生长季高温的"滞后效应"在老龄组云杉体现的更为突出;幼龄组与中龄组云杉对当年6月份降水持续增加显示出明显的负相关关系,上年12月份的降水会对幼龄组和老龄组云杉径向生长不利。研究表明幼龄组云杉包含的气候信息要优于中龄组和老龄组云杉,在该区域进行相关研究时应根据研究需要选取不同年龄跨度的云杉年表。     

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.     

Variability of climate–growth relationships along an elevation gradient in the Changbai Mountain, northeastern China

In order to explore climate–growth relationships at different elevations, tree-ring width chronologies of larch (Larix olgensis) were developed from three sampling sites on the northern slope of the Changbai Mountain, northeastern China. There were no consistent trends in statistical characteristics of the tree-ring chronologies along the elevation gradient, since trees in the forest interior had a complacent growth pattern. Monthly mean temperature and monthly total precipitation were used for the analysis. Correlation analysis indicated that temperatures in winter had negative correlations with tree growth (previous November, December and current March for the low-, mid- and high-elevation sites, respectively). The correlations between tree growth and June temperature varied from weakly negative at low elevations to significantly positive at high elevations. Precipitation in June of the growth year had negative relationship with the high-elevation chronology. However, high precipitation was associated with low temperature in early growing season, further supporting that temperature is a growth-limiting factor at high elevations. Our results suggest that along the elevation gradient, L. olgensis may respond in different ways to local climate change.     

秦岭中西部油松径向生长对气候因子的响应差异研究

在气候变暖背景下,树木径向生长对气候因子的响应会随区域干湿变化而有所差异。秦岭属于气候敏感区和生态脆弱区,南北气候特征差异明显,分析气候变化背景下树木径向生长对气候因子及干旱事件的响应,对准确预测未来气候变化对树木生长的影响至关重要。为探究该地区不同干湿环境下油松对气候因子及干旱事件响应的特点及差异,共采集秦岭中西部南北坡共4个样点的油松树轮样芯,利用树木年轮生态学的方法,分析各地油松年表与气候因子之间的关系,通过计算抵抗力、恢复力、恢复弹力等指标探究树木径向生长对干旱事件的应对能力,结果表明：1)在西部和北坡的3个样点,油松径向生长主要与前一年7—9月、当年5—7月的气温呈显著负相关,与当年5月降水呈显著正相关,在中部南坡油松径向生长主要与当年2—4月、9月气温呈显著正相关,与当年4月降水呈显著负相关;2)生长季气温升高所引发的水分亏缺,是研究区西部和北坡油松径向生长受限制的主要原因,且中部南坡油松生长受气温和干旱因子的制约要明显弱于其它3个样点;3)西部北坡油松对干旱的抵抗能力、恢复能力及恢复弹力均弱于西部南坡及中部北坡油松。在未来对研究区树木的管理与保护工作中,应更加关注西部北坡...     

大兴安岭林区南、北部天然樟子松生长对气候变化的响应差异

利用树木年代学方法,建立大兴安岭林区南、北部樟子松(Pinus sylvestris var.mongolica)年轮宽度年表,探讨樟子松径向生长对气候变化的响应差异。结果表明,南部(阿尔山、海拉尔)树轮宽度主要与当年4—9月的平均标准化降水蒸散指数SPEI(Standardized Precipitation Evapotranspiration Index)极显著正相关(r=0.639,P0.01),而北部(漠河、塔河)树轮宽度主要与同时期的平均最低温极显著正相关(r=0.488,P0.01)。说明南部樟子松径向生长主要受当年4—9月的水分限制,北部主要受同期平均最低温调控。两个地区树木生长对降水的响应一致,对当年4—9月(6月除外)的温度响应相反。近几十年来随着温度显著升高(P0.01),南部树木生长对4—9月平均最高温的负响应不断增强,而北部树木对同时段平均最低温的正响应更加明显。同时,南部樟子松生长量快速下降(r=0.612,P0.001),而北部生长量显著增加(r=0.474,P0.001)。研究发现,高温加剧干旱胁迫是南部樟子松生长量下降的主要原因,而北部樟子松生长量增加是受到4—9月平均最低温和降水量的相互作用。如果持续变暖,未来樟子松分布区可能北移。     

中国东南部不同海拔亚热带森林中马尾松径向生长对气候的响应

为了解我国东南部亚热带森林不同海拔树木生长对气候响应的差异,建立了福建省武夷山脉东麓2个样点的4个马尾松(Pinus massoniana)轮宽年表,对树木径向生长与气候因子进行了bootstrapped相关分析和线性混合模型(LME)拟合。结果表明,在高海拔地区马尾松径向生长对气候因子年际波动敏感性较强,主要表现为与生长季前冬季光温条件以及生长季内7月降水的正相关,生长-气候关系在不同样点间表现出较强的一致性。线性混合模型可以较好地拟合高海拔树木生长变化,当使用前1年12月平均日最高温、当年1月日照时长和当年7月降雨量3个气候变量进行拟合时,模型解释量达到0.5,其中前1年12月最高温和当年1月日照时数在模型中起到主导作用,累积相对贡献率约占80%,说明生长季前冬季的光热条件是限制高海拔马尾松径向生长最主要的气候因子。因此,我国亚热带地区高海拔的树木径向生长可能对未来气候变化有更强的敏感性,相关森林管理政策的制定需要将此纳入考虑;同时我国亚热带地区高海拔森林中的树木有被用于树轮气候重建的潜力。     

长白山红松不同树高处径向生长特征及其对气候的响应

利用长白山红松不同树高(0.3、1.3、4、10、15、20、25 m)处的径向生长资料,分析各树高处径向生长特征,建立红松生长与气候因子的相关关系,以期完善红松种群对气候变化的响应机制。结果表明:(1)红松不同树高处年径向生长量变化趋势基本一致,除在1980年前后,20 m处径向生长量出现异常增加外,其他各高度径向生长均出现下降趋势,红松基部和顶端(0.3、1.3 m和20 m)处径向生长年际变化更明显。随着树高增加,各处年径向生长率有所降低,0.3m处生长速率最大,且与10 m和15 m处径向生长差异显著(P < 0.05)。(2)不同树高处径向生长对气候因子的响应存在明显差异,10 m树高是红松径向生长对温度和降水响应差异的分界线。10 m以下红松径向生长主要受到生长季温度的负作用,尤其是4 m处,与当年生长季初期(4月和5月)温度显著负相关(P < 0.05)。0.3 m和1.3 m处径向生长分别与上年9月平均温度显著正相关(P < 0.05),当年6月平均和最高温度显著负相关(P < 0.05)。随着树高上升,降水对径向生长的促进作用增强,而温度对径向生长的作用也发生改变。10 m(含)以上则受到温度和降水的共同作用。10 m处径向生长对气候因子响应最敏感,受到当年生长季高温的抑制作用,还与上年和当年生长季末(9月)降水显著正相关(P < 0.05)。15 m处径向生长与上年9月最低温度和降水显著正相关(P < 0.05),而与当年5月月平均温度显著负相关(P < 0.05)。20 m处径向生长与当年3月月平均、最低和最高温度,当年7月月平均温度以及当年5月降水显著正相关(P < 0.05),而与当年1月降水显著负相关(P < 0.05)。     

Age-dependent tree-ring growth responses to climate in Qilian juniper (Sabina przewalskii Kom.)

Qilian juniper (Sabina przewalskii kom.) is one of the dominant tree species on Qinghai-Tibetan Plateau and has been used in dendroclimatological studies. Here we designed a test to examine whether or not the climate–growth responses in tree rings of Qilian Juniper vary with the change in tree's age. A total number of 135 increment cores were sampled from Qilian Juniper trees at five sites, in which 112 cores were selected and grouped into five 100-year age classes for analysis of age-dependent climate–growth relationships. Chronology statistics, response functions and ANOVA F-test were used to test the consistency of five age-class mean chronologies (AGCs). The results showed that mean sensitivity (MS) and standard deviation (SD) did not change significantly with age. Response function analysis indicated that (a) climate accounts for a high amount of variance in tree-ring widths; (b) tree-ring growth has significant positive correlation with mean monthly air temperature of previous October and November, and with total monthly precipitation of current January and June, while has significant negative correlation with mean monthly air temperature of current May; and (c) AGC-2, AGC-3 and AGC-4 have stronger response to climate change than AGC-1 and AGC-5. The ANOVA F-test showed that generally there are significant differences between the first age class and other four age classes, but among the four classes in which trees are older than 200 years, the differences are usually insignificant. Overall the long-lived Qilian Juniper is still an ideal tree species for dendroclimatic reconstruction.     

Long-term changes in tree-ring–climate relationships at Mt. Patscherkofel (Tyrol,Austria) since the mid-1980s

Although growth limitation of trees at Alpine and high-latitude timberlines by prevailing summer temperature is well established, the loss of thermal response of radial tree growth during last decades has repeatedly been addressed. We examined long-term variability of climate–growth relationships in ring width chronologies of Stone pine (Pinus cembra L.) by means of moving response functions (MRF). The study area is situated in the timberline ecotone (ca. 2,000–2,200 m a.s.l.) on Mt. Patscherkofel (Tyrol, Austria). Five site chronologies were developed within the ecotone with constant sample depth (≥19 trees) throughout most of the time period analysed. MRF calculated for the period 1866–1999 and 1901–1999 for ca. 200- and ca. 100-year-old stands, respectively, revealed that mean July temperature is the major and long-term stable driving force of Pinus cembra radial growth within the timberline ecotone. However, since the mid-1980s, radial growth in timberline and tree line chronologies strikingly diverges from the July temperature trend. This is probably a result of extreme climate events (e.g. low winter precipitation, late frost) and/or increasing drought stress on cambial activity. The latter assumption is supported by a <10% increase in annual increments of ca. 50-year-old trees at the timberline and at the tree line in 2003 compared with 2002, when extraordinary hot and dry conditions prevailed during summer. Furthermore, especially during the second half of the twentieth century, influence of climate variables on radial growth show abrupt fluctuations, which might also be a consequence of climate warming on tree physiology.     

Tree-ring variation,wood formation and phenology of beech (<Emphasis Type="Italic">Fagus sylvatica</Emphasis>) from a representative site in Slovenia,SE Central Europe

Long-term variation in tree-ring widths (1873–2006) and intra-annual dynamics of cambial activity and tree-ring formation in 2006 were studied in mature beech (Fagus sylvatica L.) trees at a typical forest site near Ljubljana (46°N, 14°40′E, 400 m a.s.l.) and related to leaf phenology and climate data. Tree-ring widths were negatively affected by minimum March and maximum August temperatures and favoured by May and July precipitation. Precipitation of the previous August and temperature of the previous November also had a positive effect. Leaf unfolding was affected by March and April temperatures, occurring later if they were low. Leaf yellowing was positively affected by minimum July temperatures and negatively by September precipitation. In 2006, leaf unfolding occurred on 16 April and was immediately followed by reactivation of cambium at breast height of the trees. One week later, the cambium obtained its maximum width (around 11 cell layers) and the rate of division increased until the end of May/beginning of June. By the end of June, 75% of the tree-ring was formed. Cambial cell divisions stopped from the end of July to mid-August. The average time of cambial activity was 100 days. Leaf yellowing occurred at the end of October, i.e. nearly 2 months after the cessation of cambial cell division. We discuss the usefulness of a combination of long-term (tree-ring width and phenology) and short-term (wood formation at a cellular level) data to understand better the environmental signals registered by a tree during growth.     

芦芽山阳坡不同海拔华北落叶松径向生长对气候变化的响应

为研究树木生长对气候变化的响应状况,选取芦芽山阳坡的3个海拔高度建立了华北落叶松(Larix principis-rupprechtii)的树轮宽度年表。年表的统计参数表明,3条年表均为研究气候信息的可靠资料。结果表明,芦芽山阳坡华北落叶松的径向生长和生长与气候的关系均具有海拔差异,中海拔(2440 m)和高海拔(2540 m)的华北落叶松具有相似年际生长变化,而二者均与低海拔(2330 m)华北落叶松的年际生长不同。低海拔华北落叶松的生长与4月平均气温和上一年11月降水量显著负相关,而中海拔和高海拔的生长均与上一年10月平均气温和6月降水量显著负相关。通过年表与气候因子之间的滑动相关分析发现,3个海拔高度华北落叶松生长与气候因子的关系均不稳定,生长与气温条件之间的显著相关关系是随着气温升高而出现的。气温的升高引起了华北落叶松生长与气温因子关系的海拔差异,以及径向生长的海拔差异。这一结果对于气候变化对植被垂直梯度影响的研究具有一定参考价值。     

升温突变对川西马尔康树木生长的影响

以采自川西马尔康林区的岷江冷杉(Abies faxoniana)和岷江柏(Cupressus chengiana)树轮为研究对象,对树轮指数与气候要素进行相关分析,研究1995年升温突变前后该区主要针叶树种的树轮响应变化。结果显示:1955—1994年时段,高、中海拔岷江冷杉径向生长对温度正响应,年轮指数呈缓慢的上升趋势,低海拔岷江柏受温度影响不大,年轮指数上升较快;1995—2012年时段,随着温度升高,3样点树木年轮指数并未上升,甚至呈下降趋势,表现出"响应分异现象"。对月气候要素的响应,树种间存在差异:高海拔岷江冷杉在前一时段主要表现为与冬季温度的正相关,后一阶段则转变为与4月温度的显著负相关及与4月份降水的显著正相关,受到显著的4月干旱胁迫影响;中海拔岷江冷杉后一时段温度敏感性消失,5月干旱胁迫加剧;低海拔岷江柏主要受降水影响,后一时段4月份干旱胁迫加剧。升温突变后,川西马尔康林区岷江冷杉和岷江柏均表现出"响应分异现象",在今后的气候重建及碳循环模拟中应加以考虑。     

Patterns and dynamics of tree-line response to climate change in the eastern Qilian Mountains,northwestern China

Tree-line ecotones are strongly climatically limited and serve as potential monitors of climate change. We employed annual growth increment from tree-rings, and tree density and age structure data derived from two Juniperus przewalskii tree-line sites in the eastern part of the Qilian Mountains, northeastern Tibetan Plateau, to detect the responses of tree growth and population dynamics to climate change. High temperature favors tree growth and is associated with increased tree density at tree-line, and an advance in tree-line position. Significantly positive correlations were found between ring-width and mean monthly air temperatures in current and previous June, July and August. Tree recruitment began to increase rapidly at the two sites after the Little Ice Age, but then decreased starting in the 1970s. The number of trees established coincides with temperature changes. The warming trend after the Little Ice Age favors increases of tree density and an advance of tree-line. The majority of trees established during the period of 1931–1970, which coincides well with the rapid radial growth of the trees.     

黄土高原中部针叶树与灌木径向生长对气候的响应差异

为揭示黄土高原中部不同树种径向生长对气候变化的响应及应对极端干旱能力的差异,构建延安任家台林场油松、狼牙刺和黄刺玫树轮宽度年表,利用帕默尔干旱指数(PDSI)定义极端干旱事件,计算干旱频率及强度;利用树轮宽度量化径向生长应对极端干旱事件的抵抗力(Rt)、恢复力(Rc)及恢复弹力(Rs)。结果表明,油松与5月平均气温和平均最高气温显著负相关,与9月平均最高气温显著正相关,与前一年11月降水和7月相对湿度显著正相关;狼牙刺与前一年9月平均气温,当年7月平均最高气温,8月平均气温和平均最高气温显著负相关;黄刺玫与7月平均气温和平均最高气温显著负相关;3个树种径向生长均与PDSI正相关。干旱程度加剧使树木抗旱性降低,导致油松、狼牙刺Rt和Rs减弱。树种间差异表现为,Rt:狼牙刺油松,Rc:油松狼牙刺黄刺玫,Rt:黄刺玫狼牙刺。     

亚热带杉木径向生长对气候因子的响应

杉木(Cunninghamia lanceolata)是亚热带地区主要造林树种之一,其在区域碳循环和缓解气候变化中起着重要的作用。以亚热带地区6个站点(荆关、马鬃岭、分宜、将乐、东风、高峰)杉木人工林为研究对象,建立树轮标准化年表,分析树木年轮年表与气候因子的关系,解析不同研究区杉木径向生长对气候变化的响应机制,探讨不同站点杉木对干旱事件的响应策略,为该地区杉木人工林的经营管理提供理论依据。研究结果表明,6个研究区杉木树轮宽度对气候变化的平均敏感度大于0.15,样本总体代表性大于0.85,均处于可接受水平,表明6个站点的杉木样本具有区域代表性,适用于进行气候相关分析。杉木径向生长主要与生长季的平均温度和降水量、上一年夏季的最低温度正相关,与当年夏季最高温度负相关,高峰站点的径向生长与7—10月的相对湿度显著正相关,其他地点径向生长与月相对湿度相关性较弱,分宜、东风和高峰站的径向生长与干旱指数显著正相关,其他地点的杉木树轮宽度与干旱指数相关性较弱。干旱事件对6个站点杉木生长均产生了负面影响,胸高断面积增长(Basal area increment, BAI)呈先上升后下降的趋势,在生长后...     

Abies spectabilis shows stable growth relations to temperature,but changing response to moisture conditions along an elevation gradient in the central Himalaya

A better understanding of growth-climate responses of high-elevation tree species across their distribution range is essential to devise an appropriate forest management and conservation strategies against adverse impacts of climate change. The present study evaluates how radial growth of Himalayan fir (Abies spectabilis D. Don) and its relation to climate varies with elevation in the Manaslu Mountain range in the central Himalaya. We developed tree-ring width chronologies of Himalayan fir from three elevational belts at the species’upper distribution limit (3750−3900 m), in the middle range (3500−3600 m), and at the lower distribution limit (3200−3300 m), and analyzed their associations with climatic factors. Tree growth of Himalayan fir varied synchronously across elevational belts, with recent growth increases observed at all elevations. Across the elevation gradient, radial growth correlated positively (negatively) with temperature (precipitation and standardized precipitation-evapotranspiration index, SPEI-03) during the summer (July to September) season. However, the importance of summer (July to September) temperatures on radial growth decreased with elevation, whereas correlations with winter (previous November to current January) temperatures increased. Correlations with spring precipitation and SPEI-03 changed from positive to negative from low to high elevations. Moving correlation analysis revealed a persistent response of tree growth to May and August temperatures. However, growth response to spring moisture availability has strongly increased in recent decades, indicating that intensified spring drought may reduce growth rates of Himalayan fir at lower elevations. Under sufficient moisture conditions, increasing summer temperature might be beneficial for fir trees growing at all elevations, while trees growing at the upper treeline will take additional benefit from winter warming.     

Spatial and age-dependent tree-ring growth responses of Larix gmelinii to climate in northeastern China

Tree-ring width chronologies from 276 Larix gmelinii cores taken in northeastern China were used to analyze spatial and age-dependent growth–climate response relationships. Tree radial growth from five localities showed similar patterns, while exhibiting different tree-ring growth responses to local climate. The rotated principal component analysis (RPCA) indicated that tree age, growing season moisture conditions, and ambient air temperature variations resulted from location differences (e.g., longitude, latitude, and altitude), which could explain the non-stationary spatial climate–growth relations observed. The study tested the fundamental assumption that the climate–growth of L. gmelinii was age independent after the removal of size trends and disturbance signals. The age-related climate–growth relationship might potentially improve the veracity of past climate reconstructions. Bootstrapped correlation function analyses suggested that the response of L. gmelinii radial growth to climate differed between trees ≥150 years old and <150 years old. Mean sensitivity and standard deviation for trees increased with age in the <150 years old tree class; whereas trees ≥150 years old had no significant relationship with age. These results showed that the assumption of age-independent climate–growth relationship is invalid at these sites. Physiological processes and/or hydraulic constraints dependent on tree age, together with detrending techniques could be the possible causal factors of clear age-dependent responses. These results suggested the importance of incorporating trees of all ages into the chronology to recover a detailed climatic signal in a reconstruction of L. gmelinii for this region.     

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。     

Responses of ring widths and maximum densities of Larix gmelinii to climate on contrasting north- and south-facing slopes in central Siberia

An analysis was performed of the climatic responses of the radial growth of Larix gmelinii (Rupr.) Rupr. at two sites—both of which included contrasting north- and south-facing slopes—in Tura, central Siberia, with the development of ring width and maximum-density chronologies for each slope. Both residual and standard chronologies of ring widths were positively correlated with temperature from late May until mid June on all four slopes. By contrast, standard chronologies of ring widths were negatively correlated with precipitation during the winter (from October to April) and in May on the north-facing slope at site 1 and on the south-facing slope at site 2 respectively. The negative correlations with precipitation during the winter and in May on some of the slopes suggested that delayed snowmelt in early spring might inhibit the radial growth of L. gmelinii, and the effects of snow are likely to vary with topography. Both residual and standard chronologies of maximum densities were positively correlated with temperature in early July on all four slopes. Maximum densities were also positively correlated with precipitation during summer of the previous year on all the slopes. These suggest that no major differences exist in terms of responses of maximum density to climatic factors between the north- and south-facing slopes.     

Dynamic relationships between Picea crassifolia growth and climate at upper treeline in the Qilian Mts., Northeast Tibetan Plateau, China

Knowledge of the spatial pattern and temporal relationships between tree-growth and climatic factors are important not only for the projection of forest growth under varying climate but for dendroclimatology in general. Here, we systematically investigated tree-growth climate relationships of Picea crassifolia at upper treeline in the Qilian Mts., northwestern China. 297 trees from eleven sites, covering a large part of the natural range of this species, show increasing and partly divergent correlations with temperature in the most recent decades. The dominant signal at all sites was a strengthening of negative correlations of annual radial growth with summer temperature. In a subset of trees at six sites, a strengthening positive correlation with summer temperatures existed as well. Wetter and high altitude sites tended to show a higher percentage of trees that are positively correlated with warming temperatures, indicating that some individuals there may take advantage of warmer conditions. Divergent responses between the two sub-populations clustered by their response to climate factor were significantly stronger in the last 30 years compared to earlier time slices. In the same time frame, hydrothermal conditions of the investigation area changed to a drier and warmer combination. Drought conditions, most likely affecting the radial growth of most P. crassifolia, have been intensifying over time and expanding spatially from the middle Qilian Mts. to most of our study area during the last half century. While explanations such as methodological effects due to trend removal or human disturbance at the sampling sites might be able to explain the result at single sites, the spatial and temporal co-occurrence of large scale changes in climate and tree growth suggests a causal link between them.