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Key message: Radial growth and wood anatomical variables of G. kola have a direct relationship with climate. Rainforest regions are more suitable and could be recommended for stakeholders for conservation action plans. Tropical agroforestry species are characterized by irregular growth and fruiting pattern, this is because of seasonal differences in the region and unanticipated environmental changes. Tree-ring width features and vessel variables could have a direct relationship with environmental conditions and factors such as precipitation and temperature could impact the growth of the species. This is because, during stressful environmental conditions, tree species record environmental changes through their physiological adjustment. Therefore, wood anatomical and tree-ring width time series was developed for Garcinia kola, a multipurpose tropical species, from a humid forest zone and derived savannah, along two vegetation zones in Nigeria. The species forms rings characterized by marginal parenchyma. The mean tree-ring width (TRW) ranges from 2.63 and 2.30 mm in the humid forest zone and derived savannah, respectively while the vessel number (VN) and vessel density (VD) are 95, 93, and 9.46, and 10.28 N/mm2 respectively. The results revealed that the radial growth of G. kola showed a positive relationship with the precipitation and the minimum temperature during the peak of the rainy season in derived savannah areas. The VN, RW, and TVA show a significant relationship with the mean annual maximum temperature in the Rainforest and derived savannah area. The vessels are more abundant in samples from the rainforest area than in the derived savannah area, the results revealed that the wood anatomical variables and TRW were sensitive to climatic variables. Hence, they could be good indicators for evaluating tropical tree responses to environmental changes in tropical agroforestry species. [ABSTRACT FROM AUTHOR]

Key message: European hornbeam has a great potential for tree-ring based research when using a combination of conventional dendrochronological techniques and fluorescent microscopy. Arasbaran forests are among the most important ecological areas in Iran, but they have been studied less extensively in comparison to the famous Hyrcanian forests. For the first time, the potential of two dominant species in these forests, i.e. hornbeam (Carpinus betulus) and stinking juniper (Juniperus foetidissima) to study the climate-growth relations was evaluated using a dendroecological approach. Difficulties in distinguishing ring-width boundaries of hornbeam were overcome using fluorescence microscopy. The statistics used to evaluate the chronologies of both species confirmed their capability to study climate–growth relationships and their potential for developing regional climate reconstruction. Hornbeam and juniper showed similar climate-growth relationships. Across all sampling sites, the growth index displayed a positive correlation with precipitation and SPEI drought index, and a negative correlation with temperature. Precipitation in spring and early autumn played a significant role in stimulating the radial growth of the species. However, topography and microclimate could affect the relationship between growth and regional climate, as the highest elevation site receives abundant moisture input from frequent fog events. Our initial study highlights the potential of hornbeam as a widely spread but neglected species in the Northern Hemisphere for dendroecological studies. Furthermore, we conclude that despite some variance in the microclimate of different sites (ranging from cold, sub-humid to warm, semi-arid) within the Arasbaran region, trees of different species in the entire study area show a common response to climatic change, mainly affected by water availability. [ABSTRACT FROM AUTHOR]

Key message: Black pine and Maritime pine exhibit considerable differences in growth phenology across elevation belts with a 1-month delay for xylogenesis and increasing growth rates from low, mid to high elevations. Investigating seasonal wood formation is crucial to understand tree growth responses to climate impact. The present study quantifies the variability of xylogenesis along an elevation gradient on the Mediterranean island of Corsica, where two native pine species (Pinus nigra Arnold ssp. laricio Maire and Pinus pinaster Aiton) grow from the upper tree line to sea level, partly in sympatry. We extracted microcores from 35 trees at 5 sites along an East–West transect from the coasts (10 m asl) to the island's central mountain ridge (1600 m asl) during bi-weekly sampling campaigns between 2017 and 2019. We applied generalised additive models to detect radial growth differences in elevation and species along with minimum temperatures for growth initiation. We found that trees in low elevations experienced over 2 months longer growth periods with higher maximum growth rates than in high elevations. The results show a 1-month delay for the beginning of tracheid formation between the low, mid and high-elevation belts but comparable timing for its termination. At the sites where both species co-occur, P. nigra accumulates more radial cells in a shorter time than P. pinaster. Trees at the two contrasting coastal sites have similar growth period lengths, but exhibit a time shift of over a month. Minimum temperatures around growth initiation vary between 3.1 °C for P. nigra and 9.9 °C for P. pinaster. These findings emphasise the high plasticity in the growth behaviour of one of the most widespread tree genera in Mediterranean and temperate zones. [ABSTRACT FROM AUTHOR]

Key message: We present the first δ18O chronology of a tropical dry forest tree species in Brazil. Our results showed a strong relationship of δ18O with inter-annual variation of moisture conditions during the growing season. In seasonally dry tropical environments, natural archives of isotopes present in cellulose of tree rings can be used to study changes in the hydrological cycle. We investigated the stable oxygen isotope ratios in tree-ring cellulose (δ18OTRC) of Cedrela odorata L. from Caatinga forest, northeastern Brazil, and tested if δ18OTRC is correlated to climate parameters. We extracted the α-cellulose from the most recent 50 tree rings (1968–2017). The inter-annual variation of δ18OTRC was strongly synchronized (r = 0.65) among all five studied individuals and closely related to changes in humidity during the growing season. The δ18OTRC was significantly correlated (p < 0.01) with precipitation (r = − 0.59), relative humidity (r = − 0.37), air temperature (r = 0.55), soil water deficit (r = 0.62) and PDSI drought index (r = − 0.62), with most significant correlation during wet season and in the first month of the dry season. The relationship with local climate variables reflects the effect of evaporative enrichment of leaf water on δ18OTRC, whereby dry soil conditions, the low relative humidity and high air temperature reduce stomatal conductance and lead to increased evaporative enrichment of δ18OTRC. Spatial correlations revealed a strong impact of PDSI in δ18OTRC. Our results also show an increase in δ18OTRC values from the 1990s onwards due to extreme and recurring droughts in northeastern Brazil. We conclude that δ18OTRC variations are related to the climatic conditions, especially during the wet period due to the greater water availability for plant physiological processes. [ABSTRACT FROM AUTHOR]

Key message: A clear carryover effect of tree-ring formation was not detected based on a pulse-labelling experiment conducted on Juniperus communis in South Germany. The inherent linkage between photosynthesis and the formation of wood is important for the understanding of relationships between tree-ring series and climate/environmental data in dendroclimatology studies. However, it is impossible to reach a mechanistic procedure of tree stem radial growth depending on its carbon balance from a traditional statistical point of view alone. Pulse labelling experiment with stable carbon isotope (13CO2) has provided innovative insights into the fate of recently assimilated carbon in organs and carbon-containing compounds. In this study, we conducted an in situ pulse labelling experiment on 27 July 2016 to examine the response of tree ring and different-aged needles to short-term elevated 13CO2 of a juniper shrub growing on a heathland in South Germany. New and old needles from four expositions were sampled before and after the experiment. A wood segment was taken from the main branch and stable carbon isotope composition (δ13C) was analysed at an intra-annual time scale. Before the experiment, the mean δ13C was − 26.8 ± 0.4‰ (mean ± standard deviation) for both needle ages, while woody tissue showed about 3‰ higher δ13C compared to needles. Substantial enriched 13C was detected in the needles after the experiment. New needles showed significant higher δ13C than the old ones 1–7 days after the experiment. Significant enriched δ13C was detected in the wood from 35 to 61% of the annual tree ring in 2016, indicating that the short-term enrichment of 13C can affect wood formation for a large section. No enhancement in 13C signal appeared in the tree ring of the subsequent year 2017, suggesting the absence of a carryover effect. Wood formation did not reply on the carbohydrates stored even 1 year before and thus tree-ring ecophysiological modelling as well as dendrochronological studies should therefore benefit from such result. [ABSTRACT FROM AUTHOR]

Key message: Increasing water-use efficiency, due to rising atmospheric CO2, did not stimulate radial growth in tropical trees, probably because negative impacts of changing climate on tree growth have overridden the small positive influence of rising atmospheric CO2. Global environmental changes affect tree growth and physiological behavior across the major biomes around the world. However, it is not yet clear how tree growth and physiology of tropical trees responded to global environmental changes in a long term, yet such information is critical to get insight into how tropical trees will respond to future global changes. The main objective of this review article is to explore the long-term trends in tree growth, carbon isotope discrimination (Δ13C), intercellular CO2 concentration (Ci), and intrinsic water-use efficiency (iWUE) across the tropics and subtropics. We distinguished between data generated on plot levels or on species or tree individual levels. Stand-level growth trends were not consistent across the studies and plots, although recent studies indicated a declining growth trend. Ci and iWUE consistently increased during the past decades, while Δ13C remained nearly constant. Increased iWUE either caused by higher photosynthetic capacity or reduced stomatal conductance did not translate into tree- and species-level radial growth, probably because assimilated carbon was allocated more to the root development to facilitate water absorption from moisture-limited soils rather than to basal area growth or xylem cell differentiation and maturation processess were impared by cavitation induced hydraulic limitations. Thus, higher temperature or drought-induced soil moisture deficit might have strongly impaired radial growth which has probably overridden the small positive effect of atmospheric CO2. Yet, disentangling the role of multiple drivers in explaining stem radial growth variation and their interactive effects on tropical trees under natural field conditions are not adequately studied and hence future research should focus on this aspect. Tree hydraulics should be taken into account in future research when predicting radial growth variability in tropical trees. [ABSTRACT FROM AUTHOR]

Key message: Intra-annual tree-ring parameters of Quercus brantii contain high-resolution intra-annual climate signals which enable us to trace seasonal aspects of climate change and to reconstruct high-resolution climate data for the semi-arid region.Abstract: Environmental conditions affect growth potential and wood-anatomical features of tree species. Hence, valuable climate signals can be extracted from intra-annual tree-ring features. In this study, we evaluated the potential of intra-annual wood parameters of Quercus brantii Lindel growing in the semi-arid southern Zagros Mountains, Iran. We analyzed earlywood width (EWW), latewood width (LWW), total ring-width (TRW), and several vessel features of the oak species. Standard chronologies have been developed for ring-width and vessel parameters using dendrochronological and quantitative wood-anatomical approaches. Correlations with local climate data showed that precipitation during the pre-growing and growing seasons had positive effects on EWW, LWW, TRW, and latewood vessel size. In contrast, earlywood vessel size showed positive correlations with precipitation in the active growing period (January-April). EWW, LWW, and TRW showed negative correlations with temperature during the pre-growing and growing seasons. Earlywood and latewood vessel features showed stronger negative correlations with mean monthly temperatures during the vessel formation period. Our results revealed that EWW, LWW, and earlywood and latewood anatomical variables of the trees contain valuable climatic signals complementing each other over different seasons. Despite the often low common signal strength of the anatomical variables shared between trees, they showed strong climate-growth relationships which can be useful for the reconstruction of seasonally resolved climate parameters in a multi-parameter tree-ring approach. [ABSTRACT FROM AUTHOR]

Key message : The paper demonstrates the prospects and applications of dendrochronology for understanding climate change effects on riparian forests in the savanna landscape. Abstract: Riparian trees in savannas have a potential for dendro-climatic studies, but have been neglected hitherto. We examined ring-width series of Afzelia africana (evergreen) and Anogeissus leiocarpus (deciduous) to study the influence of climatic factors on the growth of riparian trees in the humid (HS) and dry (DS) savanna zones of the Volta basin in Ghana. A total of 31 stem discs belonging to A. africana and A. leiocarpus were selected from HS and DS to establish species-specific local chronologies of tree growth. Each individual of A. africana and A. leiocarpus from the two savanna sites showed distinct growth rings. Cross-dating of individual tree-ring patterns was successful using standard dendrochronological techniques. The mean annual growth rates of A. africana in the HS (1.38 ± 0.09) and DS (1.34 ± 0.08) were not statistically different. Furthermore, mean annual growth rate of A. leiocarpus in the DS (3.75 ± 0.27) was higher than in the HS (2.83 ± 0.16) suggesting that species in drier environment can have higher growth rates when sufficient soil moisture is available. The growth rates of both species at the same sites were different, which might indicate different water use strategies. High correlations of individual tree-ring series of A. africana and A. leiocarpus trees at HS and DS suggest a strong climatic forcing controlled by the seasonal movement of the inter-tropical convergence zone. The annual growth of A. africana and A. leiocarpus at both the HS and DS was significantly correlated with local temperature and precipitation. The negative correlations of the growth of the two tree species to global sea surface temperatures were however, indications that the growth of riparian forests can be impacted during El Niño-Southern Oscillation years. The result of our study shows that riparian trees in the humid and dry savanna zones of West Africa can be successfully used for dendrochronological studies. [ABSTRACT FROM AUTHOR]

Key message : Cambial activity of ~100-year-old Qilian juniper trees initiated before the middle of May at an elevation of 3200 m a.s.l.; June and July were the main stem radial increment period. Around the middle of August, all xylem cell differentiation periods are completed. Precipitation or relative humidity is the main limiting factor for tree radial growth on the northeastern Tibetan Plateau. Abstract: Previous studies have found that annual tree-ring width series of Qilian juniper ( Sabina przewalskii Kom.) in the northeastern Tibetan Plateau (TP) are mostly moisture controlled, irrespective of site elevation. Knowing precisely the cambial growth dynamics during a vegetation period can lead to a better understanding of the climatic factors driving regional tree growth patterns. We observed wood formation with micro-cores taken at weekly intervals from late April to early October 2013, and monitored daily stem radial changes with high-resolution electronic point dendrometers in 30-min intervals. Dormant cambium contained 5-6 cell layers in the cambium zone. Cambial activity initiated before the middle of May in all the monitored trees. About three quarters of the total cell production or radial growth formed during June and July. Lignification of secondary walls of new xylem cells continued from end of May to middle of August. After the middle of August, the cambium entered into the inactive period. Dendrometer measurements confirmed that June and July were the main stem radial increment period. Nonparametric Kendall's Tau correlations indicate that daily relative humidity and precipitation significantly influence stem growth in May. No obvious relationships were detected in June. In July, significant negative influences of maximum temperature and positive effects of relative humidity prevailed. Overall, growing season precipitation or associated relative humidity is the limiting factor for tree stem radial increments on the intra-annual scale. Our results present a thorough understanding of Qilian juniper xylogenesis and its climate forcing within the whole growing season on the northeastern TP. [ABSTRACT FROM AUTHOR]

Key message: Spring temperature is a major limiting factor at the beginning of the growing season, the timing of growth initiation can increase by about 7 days/°C. During the growing season, impacts of climate variables on radial growth are similar along an altitudinal gradient. Abstract: Altitude is considered as an important factor affecting tree growth in mountain forest ecosystems. In this paper, the results of a 2-year field study along an altitudinal gradient in the cold and arid central Qilian Mountains, northwestern China, are reported. Twelve Qilian juniper trees ( Sabina przewalskii Kom.) were monitored with high-resolution dendrometers at three altitudes ranging from 2,865 to 3,550 m. At each altitude, a local weather station was installed close to the studied trees. We identified correlations between intra-annual growth patterns derived from the Gompertz equation with local air temperature and precipitation data. The timing of growth initiation became earlier and the growing season duration increased with decreasing altitude. The onset of radial growth occurred between early May and early June, and the growing season terminated between mid-July and late August, resulting in a growing season duration that decreased from 107 to 41 days as elevation increased. June is the most important growth period at each altitude. Spring temperature, which is strongly associated with elevation, is a critical factor determining the initiation of radial growth. The timing of growth initiation was delayed by 3-4 days per 100 m elevation. When associated with the modeled altitudinal spring temperature lapse rate of −0.48 °C/100 m, the onset of the growing season increased by about 7 days/°C. However, during the growing season, daily stem radial increments showed a positive correlation with precipitation and a negative correlation with daily maximum air temperature at all altitudes. Our study provides new data revealing the basic growth processes of Qilian juniper trees and provides significant information to quantify the responses of tree growth to future global warming. [ABSTRACT FROM AUTHOR]

Key message: We propose a new methodology to identify intra-annual density fluctuations in latewood using cell features and relative radial position within the latewood of pine trees growing on Corsica, France. Climatic forcing of latewood wood anatomical anomalies was analyzed. Abstract: We analyzed latewood anatomical features from Corsican pine ( Pinus nigra ssp. laricio) of high-elevation sites in Corsica (France) derived from digital images of the wood surface. Latewood of each ring during the period 1950-2008 was partitioned into ten equal parts P1-P10. Mean values of the cell parameters cell lumen area (CLA), radial cell width (RCW), radial cell wall thickness (CWT), and modeled latewood density (MLD) were calculated for P1-P10. The cellular profiles for each cell parameter were subjected to principal component analyses. It was possible to quantify macroscopically visible variations of wood anatomy like intra-annual density fluctuations (IADFs) by latewood profiles of different cell parameters. A combination of cell parameter characteristics including their relative radial position within latewood provides a quantification of the cell anatomical variations in an IADF. Individual cell parameter chronologies and principal components of cell parameter profiles were correlated with climate data to determine the climatic forcing on latewood formation. Average cell parameter profiles and deviations from the long-term means are able to describe 'normal' and 'anomalous' environmental conditions during latewood formation. Cell feature anomalies throughout the latewood during individual years allow the reconstruction of past weather conditions with a high temporal resolution. [ABSTRACT FROM AUTHOR]

Key message: Distinct species-specific differences were found in the response to temperature, precipitation and the self-calibrated Palmer Drought Severity Index that are confirmed by pointer year analyzes and superposed epoch analyzes. Abstract: Trees in urban environments are exposed to heat stress, low air humidity and soil drought. The increasing temperatures and the more frequent heat and drought events will intensify the stress level of urban trees. We applied a dendrochronological approach to evaluate the species-specific suitability under increasing risk of drought of five tree species at highly sealed urban sites in the city of Dresden (Germany). Climate-growth correlation analyses show that temperatures and water availability from April to July in the current year and in summer and autumn of the previous year are the main determining factors for radial growth. However, distinct species-specific differences were found in the response to temperature, precipitation and the self-calibrated Palmer Drought Severity Index. During the study period, the influence of temperature and drought on radial growth during summer months increases for Acer platanoides and Acer pseudoplatanus, whereas no changes occurred for Quercus petraea, Quercus rubra, and P. × hispanica. Pointer year analysis and superposed epoch analyses revealed a species-specific response to extreme climatic events. While for A. platanoides and A. pseudoplatanus a higher number of negative pointer years and significant growth declines in drought years were found, Q. petraea and Q. rubra showed more frequent positive pointer years but no significant growth reductions during drought. Based on these response patterns we classified the studied tree species according to their suitability and drought tolerance for urban sites. [ABSTRACT FROM AUTHOR]

Key message: Xylem anatomical traits can be categorized into two groups: plastic properties which show a high inter-annual variability, and static characteristics which vary in a more conservative range. Abstract: Water conduction in broad-leaved trees depends mainly on the size, number, and arrangement of vessels, which vary from year to year in response to varying exogenous factors, thus contributing to a safe and/or efficient water transport. However, the nature of such compensation is not clear; in particular, it is not obvious which traits act independently and which ones coincidentally. To better understand these inter-relations, tree-ring width (TRW), vessel-related anatomical traits, and the theoretical hydraulic conductivity were measured or modeled in the last 50 growth rings of mature Oriental beech trees growing at different altitudes in northern Iran. The study trees followed similar strategies compensating the effects of external factors by modifying their vessel-anatomical features. TRW and the number of vessels per unit of area were highly but negatively correlated and both were affected by exogenous factors. However, a decrease in vessel frequency (VF) is not a mirror effect of wider tree rings, but trees actively control the number of vessels produced. Principal component analysis revealed that the features VF, TRW and relative total conductivity were more plastic, whereas average vessel-lumen area, tree-ring porosity, and relative specific conductivity behaved more static. Moreover, we suggest that in theoretical approaches, total hydraulic conductivity rather than the specific hydraulic conductivity is a better indicator of a tree's hydraulic behavior in a given growing season. [ABSTRACT FROM AUTHOR]

The southern Tibetan Plateau forms the ecotone between forest areas and alpine steppes and thus, tree growth is expect to react sensitive to climate variability in this semi-humid region. We sampled 328 increment cores from 169 trees at two study sites at four elevations along altitudinal transects from 4,000 to 4,500 m a.s.l. to evaluate elevation-dependent tree growth-climate relationships of Juniperus tibetica. Standard dendrochronological statistical parameters like mean inter-series correlation (Rbar), expressed population signal as well as signal-to-noise ratio is not significantly correlated to elevation. Mean segment lengths and average growth rates of the tree-ring series increase with elevation. Correlation and response function analysis with available climate data indicate that elevation has no significant effect on tree growth-climate relationships. Instead, local tree growth is mainly driven by common regional climatic signals as it is also indicated by significant correlations between all chronologies over their common period of A.D. 1550-2010. Moisture variability during April-June has the highest impact on tree growth, even close to the upper tree limit. [ABSTRACT FROM AUTHOR]

The cambium dynamics and wood formation of Oriental beech ( Fagus orientalis Lipsky) was investigated during the 2008 growing season in the Nowshahr Hyrcanian forest, Iran (36°N, 51°E). Three study sites were selected along an altitudinal gradient (650, 1,100 and 1,600 m a.s.l.), and cambial activity rates of cell formation and cell maturation were studied on micro-cores collected in intervals of 10-20 days. The cambium reactivation of the low-altitude (L) and mid-altitude (M) trees occurred contemporaneously in late March, and also the consecutive phases of cell differentiation took place almost at the same time; however, the entry into cambial dormancy varied considerably from late August to mid-November. Due to lower temperature, the upper-altitude (U) trees showed a 10-day delay in their cambium reactivation, an earlier entry into cambium dormancy (mid-September) and a slower growth rate resulting in narrower tree rings. Despite these differences, the daily increment rates of the trees at all sites reached maximum values coincidently in the early June. Since the photoperiod is the only common external factor among different sites, it is concluded that the timing of the highest growth rate is controlled by the photoperiod. [ABSTRACT FROM AUTHOR]

Munessa Forest is a mountain forest in south-eastern Ethiopia experiencing seasonal rainfall variation. We investigated seasonal cambial activity and dormancy from increment rates of four different tree species belonging to varying life forms, namely, evergreen native conifer ( Podocarpus falcatus), evergreen introduced conifer ( Pinus patula), evergreen broadleaved tree ( Prunus africana) and deciduous broadleaved tree ( Celtis africana). Measurements of stem radius fluctuations were registered with the help of high-resolution electronic dendrometers. Daily amplitudes of stem diameter variations and daily and monthly net growth rates were determined and related to climatic variables measured at local climate stations. Thin sections of wood collected with a microcorer every 3-6 weeks allowed a visual control of newly formed wood cells during consecutive time intervals. Lack of water availability during the long dry season induced cambial dormancy of 5-7 months depending on life forms. After the onset of the short rainy season, stem swelling started quite synchronously with a variation of only single days in all studied species. Evergreen tree species were able to initiate wood formation during the short rainy season, whereas growth in the deciduous broadleaved species started in the long rainy season. The acquired data provide a basis for delineating the species-specific growth boundaries and the duration of the cambial growing season. [ABSTRACT FROM AUTHOR]

Stem diameter increments of the broadleaved deciduous tree species Tabebuia chrysantha were measured with high-resolution dendrometers in a tropical lower montane forest and in a dry forest in southern Ecuador, the latter showing a distinct dry season. Those analyses were complemented by wood anatomical studies on regularly collected microcores to determine the season of active cambial growth and the time of formation of annual growth boundaries. The length of the cambial active period varied between 3 and 7 months at the tropical lower montane forest and 2 and 4 months in the dry forest, respectively. During dry days, amplitudes of daily stem diameter variations correlated with vapour pressure deficit. During October and November, inter-annual climate variations may lead to dry and sunny conditions in the tropical lower montane forest, causing water deficit and stem diameter shrinkage in T. chrysantha. The results of the climate-growth analysis show a positive relationship between tree growth and rainfall as well as vapour pressure deficit in certain periods of the year, indicating that rainfall plays a major role for tree growth. [ABSTRACT FROM AUTHOR]

The article provides information regarding sap flow and hydraulic functioning of trees. It depicts that for trees growing in tropical and subtropical environments, high transpiration at nights indicates nutrient uptake benefits. Topics including plant functional traits, experimentation on artificially drought-stressed trees and ecophysiological measurements using water and carbon transport model, are discussed.

The author reflects on discussions of wood anatomical aspects in relation to forest ecosystem in the international conference “Wood Structure in Plant Biology and Ecology" held in Naples, Italy from 17 to 20 April, 2013. An overview of topics including dendrochronology, tree physiology and ecological influences which were discussed is mentioned. Several papers linking wood structural characteristics to forest environment resilience and resultant forest management strategies are mentioned.

An introduction to the journal is presented in which the editor discusses various reports within the issue on topics including shifts in atmospheric circulation patterns, climate-growth relationships in different climatological realms, and development of tree-ring research in South Asia.

An introduction to the issue is presented, in which the author discusses topics in tropical dendroecology and tree-ring studies presented at the Society for Tropical Ecology (GTOE) and Association for Tropical Biology and Conservation (ATBC) conferences in Germany in July 2009.