Dendrochronologia最新文献

Platanus orientalis is a key riparian species in central Iran with the potential to serve as a climate and streamflow proxy within this region. However, there are limited studies concerning its dendrochronological potential and climate-growth relationships. Therefore, this study investigates the dendroclimatic potential of P. orientalis along the riparian ecosystem of the Zayandeh-Rud River in central Iran. A total of 50 trees were sampled and analyzed at two distinct basin sites, representing varying elevations, climate characteristics, and water availability. Our findings reveal that the tree-ring width index (TRWI) at the lower basin site, which is characterized by higher temperatures, and lower precipitation, is positively affected by streamflow in May and July. This relationship is highly dependent on the amount of precipitation in the upper and lower basin sites. Moreover, analyses reveal a significant negative relationship between TRWI and temperature during the growing season at the lower basin site. In contrast, trees at the upper basin site, characterized by higher precipitation, show weaker climate-growth relationships. These findings imply that P. orientalis tree-rings could provide insight into long-term climatic patterns within riparian ecosystems in central Iran.

Leaf and stem phenology are critical drivers of tree growth patterns in seasonal climates, but the implications for species differences in radial stem growth dynamics are still poorly studied. In our study, we compared the leaf phenology and stem phenology with the underlying cell development as well as annual stem growth between five diffuse-porous (DP) and five ring-porous (RP) coexisting angiosperm species in cold and humid temperate forests. Our results show that RP species unfolded leaves later but initiated wood growth earlier compared to DP species. Yet, xylem vessel maturation in the stem started in June and was remarkably synchronized between DP and RP, which implies that species from both functional groups can effectively avoid vessel cavitation potentially triggered by late spring frost. DP species exhibited one peak in stem growth across the growing season reflecting a uniform vessel formation pattern. Instead, RP species exhibited two peaks in stem growth, with the first peak reflecting expansion of early-wood vessels and the second peak related to subsequent fiber and vessel proliferation in the late-wood. In general, species with a greater number of growth days from the start of cambium activity until full lignification of cells exhibited higher annual stem growth, regardless of species group. The observed differences in leaf and stem phenology between DP and RP species are discussed with respect to the adaptation potential of the two functional groups to changing climate conditions in cold and humid temperate forests.

Dendrochronological studies have increasingly explored tropical and subtropical trees, mainly focusing on their climatic signals. In the neotropics, growth ring width chronologies of Araucaria angustifolia have been developed at several localities in the south of its distribution, in the Atlantic forest biome. However, the signals identified in these studies indicate different patterns of growth response to climate. Understanding the causes of this variability in dendroclimatic signals is important to guide future dendrochronological studies with A. angustifolia. In this work we test the premise that at independent sites, but under similar environmental conditions, chronologies of A. angustifolia exhibit a common growth signal determined by limiting climatic conditions. We developed a new ring width chronology and correlated it with another one already published, both located in Curitibanos municipality, Santa Catarina state, Brazil and with similar climatic, edaphic and vegetational conditions. The chronologies, with reasonable level of internal growth synchrony and sampling effort, showed a common growth signal of moderate magnitude. This common growth pattern between the sites, represented by a regional chronology, showed significant correlations with local climatic variable and with El Niño Southern Oscillation (ENSO), with weak magnitudes. Partial correlations showed that this set of climatic variables was determinant of the common signal between the sites. Our results confirm the validity of the tested premise. Under the conditions studied, the growth response of A. angustifolia to climate is driven by yearly variation in temperature, which operate at different stages of the annual growth cycle and are influenced by ENSO. The low sensitivity of growth to climate is possibly related to the combined influence of multiple climatic factors and/or to moderate growth variability within sites. The multiplicity of climatic factors influencing growth of A. angustifolia trees may also explain some variability of climatic signals reported for with this species.

The intra-annual stable isotope approach emerged in the 1970s as a cornerstone in dendrochronology temporal resolution. Despite the recent progress, it still grapples with methodological and interpretation hurdles that limit its potential. Aiming at stepping forward and envisaging the systematization of the intra-annual approach, we systematically reviewed the literature using a search expression on SCOPUS that resulted in 132 eligible studies. From each study, we gathered data on sampling sites, stable isotopes, studies’ goals, sampling methods, and results interpretation. This review points to geographical biases reflecting the early dendrochronological development in temperate sites, disbelief in tropical tree rings, and the eventual limited access to high-end methods in developing countries. Although methods like laser microdissection and ablation-combustion open new research avenues, cheap razor blades are the primary sampling tool. If sampling is not the bottleneck, the number of analyses is because of the trade-off between the number of intra-annual samples and the chronology length observed in the studies. Dendroecological studies rely on dozens of intra-annual samples obtained across short tree-ring series, whereas dendroclimatological studies assess a few segments, often earlywood and latewood, over centuries-long series. We also identified two main approaches in the analyses of the intra-annual data, either the studies obtained intra-ring samples and analyzed them on an interannual basis using long-established dendrochronological methods to address common question in dendroclimatology and dendroecology, or they analyzed the seasonal variability of the intra-annual stable isotopes using novel statistical approaches addressing new research questions. These questions range from the potential to reconstruct short-term extreme climate events to a detailed evaluation of the responses of trees to environmental stress. Based on the analyses of these studies, we bring five propositions for methodological advances and discuss future research avenues. These prospects and propositions are a starting point for systmatizing the intra-annual stable isotope approach and fostering research.

The DIrect REConstruction Technique (DIRECT) is a dendroclimatological method that constructs a climatic response surface to account for changes of climatic response with tree age. This surface is then used as a transfer function for climatic reconstructions. Unlike widely-used standardization methods such as the traditional curve-fitting approach, the regional curve standardization, and their signal-free modifications that perform detrending explicitly, DIRECT accounts for age-size related trend in tree-ring measurements by construction of the response surface dependent on two variables: tree-ring parameter (width, blue intensity etc.) and cambial age. The method is capable of taking into account nonlinear climatic response of trees and differing response of younger and older trees. Here we describe an application of the newly developed open-source Python package that implements DIRECT (https://github.com/Gr1Lo/direct) to one real and one theoretical dataset. The package consists of functions for reading the initial data, constructing a response surface, and for reconstructing climate variables via this surface. The functions for visual assessment of the initial data and for the estimation and selection of parameters for constructing the response surface are also presented. Also here we provide a comparison of the DIRECT method with traditional standardization-reconstruction routines.

Dendrometers offer valuable insights into how tree growth responds to climatic variables and physiological processes over the course of a year. Yet, their applicability to extremely slow-growing trees, such as those in peatlands, has been limited due to the intricate and slow nature of growth, therefore rendering interpretation of results complex. In this study, we conducted a comprehensive monitoring of tree wood formation in both peatland and mineral soil ecosystems in southern Sweden (58.37 N, 12.17 E, 75 m asl) in 2021 and 2022, using both band and point dendrometers. To verify and validate the dendrometer data, we also sampled microcores every two weeks during both growing seasons. We find that peatland trees grow at approximately 30 % the rate of their neighbors on mineral soils. The onset of growth among peatland trees typically occurs between mid-May and early June, consistently lagging the start of the growing season in trees on mineral soils by one to three weeks. Notably, growth peaks are synchronized across peatland trees and coincide with the summer solstice. Both types of dendrometers exhibit varying degrees of accuracy depending on the phenological stages measured. They perform well in identifying growth onset and peak but are less effective at detecting growth cessation. Point dendrometers demonstrate superior accuracy as they better capture daily irreversible growth increments. In the case of band dendrometers, growth increments are obscured by greater reversible fluctuations in dead bark tissues. However, they remain valuable for tracking the wood phenology of trees with growth rates exceeding 2 mm/year. Based on our results, for an effective tree monitoring in peatlands, we strongly recommend (1) using point dendrometers and (2) removing the dead bark tissues on monitored trees.

Wood formation plays a crucial role in forest productivity and carbon sequestration. Changes in early xylem phenology influence wood development (xylogenesis) and tree growth, thereby affecting carbon uptake by forests. However, a deeper understanding of long-term shifts in spring growth phenology in response to climate warming is lacking. Process-based simulation models, such as the Vaganov-Shashkin (VS) growth model, could be used to simulate and trace shifts in spring growth phenology. We propose upgrading the VS model with a new function that considers the temperature-photoperiod interaction and improves the simulation of growth onset timings. To assess this refined VS model, we compared the early growing xylogenesis phases of two conifers (Pinus pinaster and Pinus sylvestris) and two ring-porous oaks (Quercus faginea and Quercus pyrenacia) coexisting in a Mediterranean continental site located in Soria, central Spain. The improved VS model successfully simulated early growing season xylogenesis during the warm-dry 2012 year, which can be considered analogous to the forecasted warmer scenarios in the 21st century. The upgraded VS model improved its ability to simulate growth onset, demonstrating the importance of considering both temperature and photoperiod. The model was then used to simulate spring phenology considering two Representative Concentration Pathways scenarios (RCP4.5 and RCP8.5) with different warming rates. An earlier, but species-specific, xylem onset was forecasted for the four tree species in response to warmer spring conditions in the late 21st century.

Cedrela fissilis is a tree species widely distributed in the tropical biomes of South America. This species has visible annual growth rings and can live for several centuries. The present study aims to (i) develop a chronology of C. fissilis to the Southern Brazilian Plateau using traditional dendrochronological methods, (ii) validate the dendrochronological dating using the radiocarbon (¹⁴C) bomb pulse method, and (iii) determine the influence of temperature and precipitation variations and their teleconnections with the tropical Pacific Ocean temperatures on the annual radial growth of this species. The ring width chronology was developed using 24 C. fissilis trees. The Schulman years of 1957, 1962, 1963, 1966, 1969 and 1974 were independently dated using the ¹⁴C bomb pulse methodology by accelerator mass spectrometry (AMS). Tree-ring indices were compared with temperature and precipitation records from stations around the study forest. The chronology covers the period 1907–2018 (111 years) and is well replicated (> 10 trees) from 1941 onwards. Statistics commonly used in dendrochronology indicate that the chronology is highly reliable and of good quality (mean series intercorrelation r = 0.49; Rbar = 0.30; EPS = 0.86; MSI = 0.40). The ¹⁴C bomb pulse of selected calendar years showed that the trees were accurately dated using the classical cross-dating approach. Precipitation from November to December (wet period) is positively correlated with tree growth (r = 0.36, n = 49; p<0.05). In addition, variations in temperature from May to July are positively correlated with ring width (r = 0.39, n = 49; p<0.05), suggesting that C. fissilis growth is favored by abundant rainfall during the growing season and above-average winter temperatures. Interannual variation in the chronology is partially modulated by El Niño 3.4 (East Central Tropical Pacific Sea Surface Temperature) during Oct-Dec (r = 0.27, n = 68, p<0.05). The growth of C. fissilis trees is directly dependent on climate variability, suggesting that more abundant precipitation and higher winter temperatures, as projected for the future climate of southern Brazil, will have a positive effect on tree growth. However, prolonged droughts and high temperatures during the growing season will have a negative impact on tree growth, even in humid forests with high soil moisture content.

Iceland, located in the climatologically sensitive subarctic zone, is one of the key areas for studying climate change and the current Arctic warming. Poor and rich heathland covers approximately 30% of Iceland, with heath vegetation being the area’s most important vegetation type. Prostrate and erect dwarf shrub and shrub species are the primary sources of dendrochronological information on the changes and characteristics of Iceland’s climate. Here, we investigate the dendrochronological potential of seven common Icelandic heathland species (Dryas octopetala, Calluna vulgaris, Salix arctica, Salix herbacea, Empetrum nigrum, Juniperus communis nana, and Betula nana) and explore the impact of climate conditions on their growth, particularly with regard to extreme meteorological events. We conducted comparative analyses among species and observed their climatic responses in a climatically, morphologically, and geologically homogeneous setting in north-eastern Iceland. After sampling, measurements, and cross-dating, we constructed local chronologies for the seven species. Of approximately 200 samples, only 113 were included in the final shrub chronologies. All chronologies covered at least 50 years, with few of them exceeding 100 years. Dendroclimatological analysis indicated that above-average temperatures in June and summer positively influence the growth of D. octopetala (June–September), J. communis (July–August), B. nana (July–August), C. vulgaris (June–August), and S. arctica (August–September). The opposite is observed for S. herbacea and E. nigrum. Climate–growth correlations indicate that the growth of these species is negatively correlated with temperature and positively correlated with winter and summer precipitation. Furthermore, among the long-lived woody species growing in Iceland, seven common species were used to assess the impact of extreme meteorological conditions on their growth. The most pronounced extreme year in the wood anatomy of Icelandic shrubs was 1979, depicted as very narrow or missing rings and as the blue ring in J. communis.

Dendrochronology utilizes mean values of individual tree-ring indices to average out noise and strengthen common signals, typically associated with climate. Expressed Population Signal (EPS) is commonly used to assess the degree to which a chronology represents the common signal. However, there is a lack of studies on how EPS reflects low-frequency signals. In this study, we propose a frequency-dependent EPS (FEPS) approach to evaluating the low-frequency signal strength. Extensive tests were conducted using tree rings from Chinese Loess Plateau. We found that as timescales lengthen, EPS decreases due to declining inter-series correlations, thus demanding larger sample sizes. This finding remains robust across different detrending methods, filtering methods, filter orders, and treatments for end effects. Determining sample sizes by standard EPS (common use of EPS with unfiltered series) has a limited impact on multi-year frequencies, but considerably influences timescales exceeding a decade. Our study reveals a prevalent underestimation of sample size requirements for robust multi-year and interdecadal signals estimation, and the FEPS approach is expected to potentially enhance our understanding of long-term climate dynamics.