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.     

Age-dependent responses of tree-ring growth and intra-annual density fluctuations of Pinus pinaster to Mediterranean climate

Dendrochronology generally assumes that climate–growth relationships are age independent once the biological growth trend has been removed. However, tree physiology, namely, photosynthetic capacity and hydraulic conductivity changes with age. We tested whether the radial-growth response to climate and the intra-annual density fluctuations (IADFs) of Pinus pinaster Ait. varied with age. Trees were sampled in Pinhal de Leiria (Portugal), and were divided in two age classes: young (<65 years old) and old (>115 years old). Earlywood and tree-ring width of young P. pinaster trees were more sensitive to climate influence while the response of latewood width to climate was stronger in old trees. Young trees start the growing season earlier, thus a time window delay occurs between young and old trees during which wood cells of young trees integrate environmental signals. Young trees usually have a longer growing season and respond faster to climate conditions, thus young P. pinaster trees presented a higher frequency of IADFs compared with old trees. Most of the IADFs were located in latewood and were positively correlated to autumn precipitation. The radial-growth response of P. pinaster to climate and the IADFs frequency were age dependent. The use of trees with different age to create a tree-ring chronology for climate studies can increase the resolution of climatic signals. Age-dependent responses to climate can also give important clues to predict how young and old trees react to climate change.     

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。     

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。     

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。     

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.     

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.     

长白山北坡不同年龄红松年表及其对气候的响应

运用树木年轮气候学方法,研究了长白山北坡红松(Pinus koraiensis)不同年龄年表特征及其与气候因子间的关系,以期揭示年龄因素对年表的潜在影响。结果表明,平均年龄为63a的红松低龄年表与平均年龄为184a的高龄年表对气候的响应明显不同:低龄红松径向生长与当年1、2月月平均温度负相关(P<0.05),同时也受到上年及当年多个月份的月平均最高温度或最低温度的影响,但与降水的相关性未达到显著水平;高龄红松径向生长则与月平均温度间的关系不明显,而与当年1、2、4、6、7、9月的月平均最高温度正相关,与当年4月、9月的月平均最低温度负相关,同时受到上年5月及当年5月月总降水量的影响。因此,年龄因素对红松年表的气候响应方面存在一定影响,且高龄年表对气候响应的敏感性更高,包含有更多的气候信息。     

Forward modeling analyses of Qilian Juniper <Emphasis Type="Italic">(Sabina przewalskii)</Emphasis> growth in response to climate factors in different regions of the Qilian Mountains,northwestern China

Key message

The process-based Vaganov–Shashkin model simulations accurately represent the nonlinear process of Qilian Juniper growth–climate relationship over different regions of the Qilian Mountains.

Abstract

The Qilian Mountains (QM), northeastern edge of the Tibetan Plateau (TP), is one of the most studied areas in China for tree-ring research; considerable dendroclimatic reconstructions have been carried out and a series of important achievements made over this region. However, most reconstructions were primarily based on empirical relationships between tree growth and climate factors identified through statistical analysis. Reliable information on the physiological processes of tree responses to climate change in different regions is still scarce. Here, the process-based Vaganov–Shashkin (VS) model was used to simulate regional patterns of climate–tree growth relationships using observed temperature and precipitation over the different regions of the QM. Results showed that the sequences of simulated growth curves were broadly consistent with the actual tree-ring chronologies in all three regions of the QM. VS model simulations accurately represented the effect of climatic controls on the growth of Qilian Juniper (Sabina przewalskii). VS model outputs closely corresponded to statistical relationships between tree-ring width and climate factors as well as observational physiological behavior; i.e., available water in May and June had the largest contribution to ring formation in Qilian Juniper over the QM. The simulated and actual data analyses revealed that the radial growth of trees in the western QM was more sensitive to moisture conditions in May and June, compared with growth in the central and eastern QM. Tree growth in this region is representative of large areas in northwestern China with drought conditions.

     

The role of larch budmoth (Zeiraphera diniana Gn.) on forest succession in a larch (Larix decidua Mill.) and Swiss stone pine (Pinus cembra L.) stand in the Susa Valley (Piedmont, Italy)

In the Alps, larch (Larix decidua Mill.) is severely affected by larch budmoth (Zeiraphera diniana Guénée) (LBM) attacks. The impact of these outbreaks on the Swiss stone pine (Pinus cembra L.) and on the dynamic processes acting in subalpine forest stands are still not well known. Dendroecological methods were used in this study to reconstruct past LBM outbreaks in Susa Valley, Piedmont, Italy. The analysis was carried out on 62 cores from larch and 101 cores from stone pine. The length and severity of each outbreak was quantified for both species and for each tree by means of the programme OUTBREAK. The frequency of the outbreaks was determined using singular spectral analysis and superposed epoch analysis was used to test the significance of the associations between outbreaks and tree-ring growth. In order to verify if trees belonging to different age classes are differently affected by LBM, the reconstructed outbreaks are then classified taking into account the cambial age of the tree at the moment of the outbreak. From 1760 to 1999, 19 outbreaks were recorded in the larch chronologies, while only three outbreaks in the stone pine chronologies. The larch growth is strongly influenced by LBM and the identified outbreaks are equally distributed in all the three age classes. On the stone pine the sporadic occurrence of the identified events made difficult any interpretation of the eventual effect of LBM. Our results lead us to argue that LBM has not played an important role both in determining the stone pine growth rate and in influencing the present observed succession from the stage dominated by larch, to a stage dominated by stone pine or by a mixed stone pine-larch forest.     

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。     

Does Soil Organic Layer Thickness Affect Climate–Growth Relationships in the Black Spruce Boreal Ecosystem?

The observed long-term decrease in the regional fire activity of Eastern Canada results in excessive accumulation of organic layer on the forest floor of coniferous forests, which may affect climate–growth relationships in canopy trees. To test this hypothesis, we related tree-ring chronologies of black spruce (Picea mariana (Mill.) B.S.P.) to soil organic layer (SOL) depth at the stand scale in the lowland forests of Quebec’s Clay Belt. Late-winter and early-spring temperatures and temperature at the end of the previous year’s growing season were the major monthly level environmental controls of spruce growth. The effect of SOL on climate–growth relationships was moderate and reversed the association between tree growth and summer aridity from a negative to a positive relationship: trees growing on thin organic layers were thus negatively affected by drought, whereas it was the opposite for sites with deep (>20–30 cm) organic layers. This indicates the development of wetter conditions on sites with thicker SOL. Deep SOL were also associated with an increased frequency of negative growth anomalies (pointer years) in tree-ring chronologies. Our results emphasize the presence of nonlinear growth responses to SOL accumulation, suggesting 20–30 cm as a provisional threshold with respect to the effects of SOL on the climate–growth relationship. Given the current climatic conditions characterized by generally low-fire activity and a trend toward accumulation of SOL, the importance of SOL effects in the black spruce ecosystem is expected to increase in the future.     

New insights into estimating the age of old Scots pine from increment cores with stem rot

Trunk inner rot is a common phenomenon in some old-growth pine dominated forests, making it impossible to determine tree age by counting annual rings. We compared the efficiency of five methods to estimate the age of hollow pine trees (Pinus sylvestris L.). Our main aims were to select the best-performing method and to test whether the age of the tree or the proportion of rot influences the accuracy of estimation. We used full increment cores (reaching the pith or within 1 cm of it) from 100 trees (54–562 years old) collected in northern Sweden and simulated rotten centres of three different sizes in order to test the methods. The lowest error rates were obtained when less than a third of the sample was missing (down to 5.0 % error rate), and by using a method based on the growth pattern of a set of healthy trees. Using linear extrapolation of the mean radial growth led to large overestimates (up to three times the number of absent rings) with error rates up to 27.3 %. We also found that the performance of all methods was reduced in cores from older trees. Our main conclusion is that non-linear methods should be preferred for age estimation of hollow pines. We also argue that more precision in the age estimation could be gained already in the field by collecting multiple cores from rotten trees or by developing alternative coring methods.     

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。     

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.     

Climatic signals in tree rings of <Emphasis Type="Italic">Burkea africana</Emphasis> and <Emphasis Type="Italic">Pterocarpus angolensis</Emphasis> from semiarid forests in Namibia

Tree-ring studies contribute worldwide to the understanding of climate and its relation to tree growth. Long tree-ring chronologies serve as climate proxies for the reconstruction of past, pre-instrument climate and its recent change. In tropical regions, the availability of exactly dated tree-ring chronologies is limited. The dendroclimatic potential of two dominant species from dry forests in northern Namibia was examined in the study presented in this paper. Both species (Burkea africana Hook and Pterocarpus angolensis DC) were sampled at two sites (ca. 900 km apart), and the response to several climatic variables, including ENSO indices, is studied. All specimens showed distinct growth rings and cross-dating between radii was successful for all trees. Species-specific mean curves were built for both sites. The mean curves of different species of the same site synchronised significantly, allowing the construction of a site-specific chronology. Synchronisation between sites was not possible, but spectral analysis of the chronologies implied that both show similar long-term (6.7 year) oscillation patterns. B. africana is more sensitive to rainfall variation than P. angolensis at both sites. Growth response to rainfall was positive, but a time-lag in the reaction occurred between the sites, corresponding to the time-lag of the beginning of the rainy season. Air temperature showed a negative correlation with stem increment at both sites. The response at the westernmost site to two ENSO indices indicates a tree growth decrease during El Niño years, which are generally dry in southern Africa.     

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.     

The effect of climate on radial growth of Quercus liaotungensis forest trees in Loess Plateau, China

Annual ring growth of Quercus liaotungensis trees in natural forests bounded by desertified region in the Loess Plateau of China was investigated for the evidence of climatic influence. Increment cores were sampled and cross-dated for 120 trees from six stands 0.5–2.5 km apart. Site tree-ring chronologies were created using general dendrochronological techniques. The results of correlation analyses between tree-ring indices and monthly climatic variables indicated that radial growth was positively correlated with precipitation in September of the previous year and that from April to June of the current year. Ring widths were negatively affected by temperature during spring and summer. In contrast, mild temperature in the previous October showed a positive influence. The results suggest that precipitation is important in the early growing season when soil and air are dry, and that high temperatures tend to reduce radial growth in this region. September rainfalls and a warm October may provide conditions that facilitate carbon storage, favor soil microbial activity, and promote root growth and shoot maturation against detrimental effects of stresses in the following seasons. There were also some differences among plots in the effects of both climatic variables probably as a result of different structures and geographical conditions that modified microenvironments. The results may contribute to the reforestation management of the area. It is expected that Q. liaotungensis forests should be ecologically established in this region on shady and half-shady slopes where air and soil drought stresses are not serious.     

Does resin tapping affect the tree-ring growth and climate sensitivity of the Chinese pine (Pinus tabuliformis) in the Loess Plateau,China?

Resin tapping could affect water and nutrient transport processes in Chinese pine trees, rendering them more vulnerable to extreme climatic events, such as drought, and affecting the ecological function of forests in semi-arid regions. This study evaluated how resin tapping affects the tree-ring growth and climate sensitivity of Chinese pine in the Loess Plateau. We compared tree-ring growth patterns between the tapped and untapped faces of tapped trees, and investigated tree-ring growth and its response to climate between tapped and untapped trees in a forest stand during the 1967–2017 period. Tapped trees showed asymmetrical growth patterns after resin tapping, with narrower rings near the tapped face and wider ones near the untapped face. Furthermore, tapped trees had inter-annual variations consistent with those of untapped trees except for the years 2000 and 2001, with significantly lower values following resin tapping, and tree-ring growth then returning to normal. The climate response analysis indicated that the tree-ring growth of both tapped and untapped trees was negatively affected by monthly mean temperatures during the early growing season (May to July) in the post-resin-tapping period. Furthermore, tree-ring growth in tapped trees also revealed significant correlation with water vapour deficit and the Palmer drought index, which indicates that tapped trees are more vulnerable to drought. Further studies based on stable isotopes (i.e. δ¹³C, δ¹⁸O, and δ¹⁵N) could improve our understanding of the physiological mechanisms that regulate the effects of resin tapping on tree-ring growth.     

Long-term growth decline in Toona ciliata in a moist tropical forest in Bangladesh: Impact of global warming

Tropical forests are carbon rich ecosystems and small changes in tropical forest tree growth substantially influence the global carbon cycle. Forest monitoring studies report inconsistent growth changes in tropical forest trees over the past decades. Most of the studies highlighted changes in the forest level carbon gain, neglecting the species-specific growth changes which ultimately determine community-level responses. Tree-ring analysis can provide historical data on species-specific tree growth with annual resolution. Such studies are inadequate in Bangladesh, which is one of the most climate sensitive regions in the tropics. In this study, we investigated long-term growth rates of Toona ciliata in a moist tropical forest of Bangladesh by using tree-ring analysis. We sampled 50 trees of varying size, obtained increment cores from these trees and measured tree-ring width. Analyses of growth patterns revealed size-dependent growth increments. After correcting for the effect of tree size on tree growth (ontogenetic changes) by two different methods we found declining growth rates in T. ciliata from 1960 to 2013. Standardized ring-width index (RWI) was strongly negatively correlated with annual mean and maximum temperatures suggesting that rising temperature might cause the observed growth decline in T. ciliata. Assuming that global temperatures will rise at the current rate, the observed growth decline is assumed to continue. The analysis of stable carbon and oxygen isotopes may reveal more insight on the physiological response of this species to future climatic changes.