Dendroclimatological Research Research Articles

Dendroclimatology: Basic Concepts, Measurement Techniques and Research Possibilities in the Republic of Srpska

Dendrochronology is a new scientific discipline whose methods are used in paleogeographic research in order to gain insight into the state, as well as changes in the environment. Dendrochronology has given rise to dendroclimatology, which is used to study climate trends in the recent period, on the basis of which it is possible to determine the changes that have taken place in the climate complex in the past. Thanks to the ability of trees to form rings in accordance with climatic influences, it is possible to determine whether there is a correlation between meteorological data and data obtained from dendroclimatological analyzes. Dendroclimatology has become an essential tool for analyzing perennial climate fluctuations and changes. The chapter presents the results of previous research and perspectives of climate reconstruction using dendroclimatological methods in the Republic of Srpska. Although it is still undeveloped in our country, this science is very important for the study of climate in the past, as well as other cause-andeffect changes related to climate oscillations. The area of the Republic of Srpska is covered by a significant percentage of forests, in which old trees are frequent. This area offers a number of advantages, but also limitations for dendroclimatological research. In the area of the Republic of Srpska, these studies were conducted sporadically until several years ago. More intensive researches in recent years create the basis for a better understanding of recent climate and paleoclimate. Having in mind the above, it can be concluded that the Republic of Srpska has significant potential for dendroclimatological research.

Increasing precipitation variability and climate-growth responses of five tree species in North Carolina, USA

We examined the effects of increasing summertime precipitation variability from 1950 to 2022 on the radial-growth responses of five tree species native to central North Carolina, USA. Tree-ring data were collected from chestnut oak, post oak, longleaf pine, shortleaf pine, and Virginia pine and processed following standard dendrochronology procedures. Adjusted latewood chronologies for each species were created and correlated with either monthly or multi-monthly combinations of summertime precipitation for above average (AA, > 1 σ above mean), below average (BA, <−1 σ below mean), and near average (NA, <−1, and 1 > σ) precipitation years. June–September precipitation variability and other summertime monthly combinations significantly increased during the study period, with a 10.2% increase in AA/BA years during the 21st century. Climate-growth correlations ranged from 0.40–0.51 using all years within the study period. However, using AA and BA years exclusively, climate-growth responses ranged from 0.44–0.71, with post oak and longleaf pine experiencing significantly higher correlations. No significant changes in climate-growth responses occurred for chestnut oak, shortleaf pine, and Virginia pine. These findings suggest the effects of increased precipitation variability on climate-growth responses are species-dependent and affected by the precipitation classification (i.e. AA or BA years). These responses help explain temporal variations in the strength of climate-growth responses, particularly for some species, and offer additional considerations for dendroclimatological research.

Impact of disturbance signatures on tree-ring width and blue intensity chronology structure and climatic signals in Carpathian Norway spruce

Tree radial growth is influenced by climatic and various non-climatic factors, which can complicate the extraction of climate signals from tree rings. We investigated the influence of disturbance on tree-ring width (RW) and latewood blue intensity (BI) chronologies of Norway spruce from the Carpathian Mountains to explore the extent to which disturbance can affect temperature signals in tree rings. Overall, ∼15000 high-elevation Norway spruce tree cores from 34 sites grouped into four regions (Slovakia, Ukraine, North and South Romania) were analyzed. The curve intervention detection (CID) method was applied to detect and correct identified disturbance trends. RW chronology structural comparisons were performed among disturbance-affected and disturbance-corrected chronologies for various spatial (regional / site) scales and sampling subsets. Structural comparisons were also performed for RW and BI chronologies developed from separate groups of series (i.e., disturbed, and undisturbed) for five sites exhibiting clear disturbance trends. Temperature sensitivity was assessed for all chronology variants of both parameters. We found that disturbance trends only affected RW chronologies at the site/subset scale with relatively small series replication and were not detected at the regional scale. Unlike RW, BI chronologies were generally unaffected by disturbance. BI data also contained much stronger growing season temperature signals, which appeared to be both spatially and temporally more coherent. Whereas highly replicated and spatially extensive datasets can help minimize or eliminate disturbance trends in RW chronologies, this potential influence should be considered when interpreting climatic signals in tree rings and reconstructing historical climate in weakly replicated periods. On the other hand, BI is a promising alternative tree ring parameter with stronger and more stable growing season temperature signals, whose seemingly disturbance-free chronology structure does not appear to suffer from this ecological bias, and therefore represents a more suitable parameter for dendroclimatological research.

Dendroclimatology in Latin America: A Review of the State of the Art

The application of dendrochronology for understanding climatic variations has been of great interest to climatologists, ecologists, geographers, archeologists, among other sciences, particularly in recent decades when more dendrochronological studies have been developed. We analyzed and identified the current state and recent advances in dendroclimatology in Latin America for the period 1990 to 2020. We carried out reviews in ScienceDirect, Web of Science, and Scopus databases with the keywords “dendrochronology”, “dendroclimatology”, “dendrochronology and climatic variability”, “dendroclimatology and climatic variability”, “dendrochronology and trend”, and “dendroclimatology and trend” for each Latin American country. Results show that dendroclimatological research in the last 11 years has increased and has been mainly developed in temperate climate zones (83%) and tropical or subtropical areas (17%), where conifer species have been the most used with over 59% of the studies. However, broadleaf species for dendrochronological studies have also increased in the last decade. Dendroclimatological research in Latin America has provided important advances in the study of climatic variability by defining the response functions of tree-rings to climate and developing climatic reconstructions. Our research identified areas where it is necessary to increase dendroclimatic studies (e.g., dry and tropical forests), in addition to applying new techniques such as isotope analysis, blue intensity, dendrochemistry, among other tree-ring applications.

Environmental changes in the late Allerød and early Younger Dryas in the Netherlands: a multiproxy high-resolution record from a site with two Pinus sylvestris populations

In the Netherlands, several proxies of climate change during the Last Glacial-Interglacial Transition (LGIT) (c. 14,700 to 11,700 b2k) have been investigated in detail over the last few decades. The present paper presents two tree-ring chronologies LETR-A (n = 16, timespan 106 rings) and LETR-B (n = 24, timespan 201 rings) from in situ subfossil pine remains (Pinus sylvestris) discovered at Leusden-Den Treek in the Netherlands that date from the Bølling-Allerød interstadial (GI-1). Using a multiproxy approach (both abiotic and biotic), it was possible to study local woodland development in detail as part of long-term environmental change. Moreover, the trees opened up possibilities for dendrochronological and dendroclimatological research. The tree-ring series show the occurrence of two successive phases of pine woodland development, which were 14C dated with high precision and calibrated using the recent IntCal20 14C calibration curve: 13,450–13,396 to 13,370–13,316 calBP (series LETR-A) and 12,952–12,937 to 12,754–12,739 calBP (series LETR-B). At the north-western boundary of its ecotone, Pinus was highly sensitive to climate change during the latter part of GI-1 and the transition to GS-1. The inability to set fruit and the disappearance of the pine woodland within decades before and after c. 12,745 calBP is interpreted as the vegetational response to abrupt climate deterioration at the start of the Younger Dryas (12,807 ± 12 cal BP).

A Norway spruce tree-ring width chronology for the Common Era from the Central Scandinavian Mountains

Fennoscandia is one of the most prominent regions in the world for dendroclimatological research. Yet, millennium-long tree-ring chronologies in this region have mainly been developed from Scots pine (Pinus sylvestris L.). To explore the possibility of building long-term chronologies using other dominating tree species in the region, this paper presents the first two millennia-long Norway spruce (Picea abies (L.) Karst.) ring-width chronology from Northern Europe. The chronology is composed of living trees and subfossil wood and covers the period from BCE 115 to 2012 CE. A sufficiently replicated and robust chronology is built for the past 360 years back to 1649 CE. Further back in time, the common growth signal is reduced, and hence the reliability of the earlier section of the chronology is lower. The climate calibration results show that the spruce ring-width correlation with June-July mean temperatures over the period 1901–2012 is positive and significant (r = 0.6, p < 0.01) and representing the temperature variability of a spatial domain covering west-central Scandinavia. These results show the ability of Norway spruce to serve as a proxy for paleoclimatic research and the possibility of extending the chronology far back in time in the region, and therefore present an opportunity for carrying out new inter-and intraregional proxy analyses.

New dendroclimatological research in oak, S (Quercus Frainetto Ten.) forestry in Šumadija-Region- (Central Serbia) as a basis for climate change monitoring

New dendroclimatological research in oak, S (Quercus Frainetto Ten.) forestry in Šumadija-Region- (Central Serbia) as a basis for climate change monitoring

New dendroclimatological research in oak, S (Quercus Frainetto Ten.) forestry in Šumadija-Region- (Central Serbia) as a basis for climate change monitoring

In this work present study to describe the survey of climatic change in the case in Šumadija-Central Serbia. Climate change due to a fragile ecosystem in semi-arid, and arid region such as Serbia is one of the most challenging climatological and hydrological problems. Dendrochronology, wich uses tree rings to their exact year of formation to analyse temporal and spatial patterns of processes in the physical and cultural sciences, can be used to evaluate the effects of climate change. In this study, the effects of climate change werw simulated using dendrochronology (tree rings) and an artificial neural network (ANN) for the period from 1900—2015. The present study was executed using the (Quercus frainetto Ten.). Tree rings width, temperature and precipitation were the input parameters for the study, and climate change parameters were the outputs. After the training process, the model was verified. The verified network and tree rings were used to simulate climatic parameter changes during the past times. The results showed that the integration of dendroclimatology and an ANN renders a high degree of accuracy and efficiency in the simulation of climatic change. The results showed that the climatic of the study area changed from semiarid, to arid, and its annual precipitation decreased significantly.

NO SIGNIFICANT INCREASE IN TREE MORTALITY FOLLOWING CORING IN A TEMPERATE HARDWOOD FOREST

The collection of tree-ring data from living trees is widespread and highly valuable in ecological and dendro-climatological research, yet there is concern that coring injures trees, potentially contributing to mortality. Unlike resinous conifers that can quickly compartmentalize wounds, less decay-resistant angiosperms may face more pronounced risk of injury from coring. To test if coring increases mortality rates in temperate hardwood trees, we leverage a unique dataset tracking the mortality of cored and uncored hardwood trees representing 19 species from 10 genera in a 26-ha plot in Virginia, USA. We compare mortality rates between 935 cored trees and 8605 uncored trees for seven years following coring. Annual mortality rates did not differ between cored trees (1.71% yr–1; 95% CI 1.40 to 2.20) and uncored trees (1.85% yr–1; 95% CI 1.70 to 2.28) across the full dataset, nor were there differences by genus or size class. These results indicate that the risk of hardwood mortality caused by increment coring is probably lower than previously assumed. However, these results cannot rule out the possibility that coring elevates hardwood mortality in other climates or when trees face multiple additional stressors that were not influential over the course of our study.

Rapid warming induces the contrasting growth of Yezo spruce (Picea jezoensis var. microsperma) at two elevation gradient sites of northeast China

Accurately assessing the impact of climate changes on tree growth or forest productivity is vital to better understand global carbon cycles. Here, we carried out dendroclimatological research on Yezo spruce (Picea jezoensis var. microsperma) along an elevation gradient in two sites to investigate the effect of rapid warming on spruce growth in northeast China. Results indicated that trees at two low-elevation sites had significantly wider ring widths and higher basal area increment (BAI) compared with high-elevation sites. Ring widths and BAI of Yezo spruce at low elevations showed a clear growth increase during the 1940s–1970s followed by a significant decline after 1980. However, trees at high elevations showed a relatively stable growth during the 1940s–1970s followed by a significant increase after 1980. Rapid warming after 1980 increased the radial growth of Yezo spruce at high-elevation sites, but reduced tree growth at low-elevation sites. Winter precipitation and growing season temperature were positively correlated with radial growth of Yezo spruce at high elevations, but negatively correlated with tree growth at low elevations. A clear pattern of growth and growth-climate relationship changed in 1980. The temperature threshold for determining the impact of climate on Yezo spruce could change with latitude or site. Difference in drought caused by warming may be the main reason for the opposite response of tree growing at different altitudes in northeast China. The mechanism of rapid warming driving contrasting growth at different elevations should also be investigated in other tree species in NE Asia. In the context of future climate warming, our findings are of great significance for tree growth in assessing forest dynamics and carbon cycling.

Two centuries-long dendroclimatic reconstruction based on Low Arctic Betula pubescens from Tromsø Region, Northern Norway

Abstract This study presents the results of dendrochronological and dendroclimatological research of Betula pubescens from four sites in northern Norway (Kvaløya Island, Tromsøya Island and Storelva Valley), which provided a 193-year chronology. Our results highlight the importance of the site selection in dendroclimatological studies. We demonstrated that activity of geomorphic processes connected with local topography could led to reduced strength of climatic signal embedded in tree-ring data. Negative pointer years, triggered mainly by unfavourable climatic conditions and insect outbreaks, were common for all site chronologies in 1945, 1955, 1965, 1975, 1986, 2004. However, some site-specific differences were also distinguished. Response function analysis confirmed that June, July and August temperatures were positively correlated with tree-ring widths. This climate-growth relationship was stable throughout the years 1925–2000. From summer temperature reconstruction back to AD 1820, two colder (c. 1835–1850 and 1890–1920) and two warmer (c. 1825–1835 and 1920–1940) periods were identified. The tree-ring record from the Tromsø Region, well correlated between series, sites and climate variables, is an important element of a large-scale reconstruction of pre-instrumental climate variation in the northeastern part of the Atlantic Ocean. Our dendroclimatic reconstruction corresponds well with other climate proxy data, like fluctuations of mountain glaciers in Scandinavia or sea ice extent.

Climate Response of Tree Radial Growth at Different Timescales in the Qinling Mountains.

The analysis of the tree radial growth response to climate is crucial for dendroclimatological research. However, the response relationships between tree-ring indices and climatic factors at different timescales are not yet clear. In this study, the tree-ring width of Huashan pine (Pinus armandii) from Huashan in the Qinling Mountains, north-central China, was used to explore the response differences of tree growth to climatic factors at daily, pentad (5 days), dekad (10 days) and monthly timescales. Correlation function and linear regression analysis were applied in this paper. The tree-ring width showed a more sensitive response to daily and pentad climatic factors. With the timescale decreasing, the absolute value of the maximum correlation coefficient between the tree-ring data and precipitation increases as well as temperature (mean, minimum and maximum temperature). Compared to the other three timescales, pentad was more suitable for analysing the response of tree growth to climate. Relative to the monthly climate data, the association between the tree-ring data and the pentad climate data was more remarkable and accurate, and the reconstruction function based on the pentad climate was also more reliable and stable. We found that the major climatic factor limiting Huashan pine growth was the precipitation of pentads 20–35 (from April 6 to June 24) rather than the well-known April–June precipitation. The pentad was also proved to be a better timescale for analysing the climate and tree growth in the western and eastern Qinling Mountains. The formation of the earlywood density of Chinese pine (Pinus tabulaeformis) from Shimenshan in western Qinling was mainly affected by the maximum temperature of pentads 28–32 (from May 16 to June 9). The maximum temperature of pentads 28–33 (from May 16 to June 14) was the major factor affecting the ring width of Chinese pine from Shirenshan in eastern Qinling.

Climate-growth Relationship of Pinus patula Schldl. et Cham. in Wondo Genet, South Central Ethiopia

Most tropical regions are facing historical difficulties of generating biologically reconstructed long-term climate records. Dendrochronology (tree-ring studies) is a powerful tool to develop high-resolution and exactly dated proxies for climate reconstruction. In particular, dendroclimatological research is important in understanding both spatial and temporal characteristics of climate influences on tree growth. This project investigated the relationship between climate (precipitation and temperature) and tree rings, and showed its potential for climate reconstruction. Owing to the seasonal variation in rainfall, we expected the formation of annual growth rings in the wood of the forest of Wondo Genet. The project also carried out annual ring assessment and described the basic anatomical features of growth ring boundaries of the species under study. Wood disc samples of 15 trees belonging to the species of Pinus patula in the study site served to develop climate sensitive ring-width chronologies using standard dendrochronological techniques. A tree ring chronology was developed for the study species, and this enabled the assessment of the existing relationship between climate and tree growth patterns. The relationship between annual and seasonal precipitation, and mean monthly maximum and minimum temperature and ring-width indices was performed by correlation and simple regression analyses. The study species showed significant relationships with the rainy season precipitation proving the existence of annual tree rings (r=0.42). Monthly correlation analysis also showed that rainfall during July had the highest positive and significant correlation with the growth of the study species (r=0.50). The results indicated that annual growth of the species is primarily influenced by water availability during the growing (rainy) season. The study generally infers that the presence of anatomically distinct annual growth rings and high-quality cross dating and climate-growth relationships make the study species useful candidate for dendrochronological studies.

How similar are annual and summer temperature variability in central Sweden?

Tree-ring based temperature reconstructions have successfully inferred the past inter-annual to millennium scales summer temperature variability. A clear relationship between annual and summer temperatures can provide insights into the variability of past annual mean temperature from the reconstructed summer temperature. However, how similar are summer and annual temperatures is to a large extent still unknown. This study aims at investigating the relationship between annual and summer temperatures at different timescales in central Sweden during the last millennium. The temperature variability in central Sweden can represent large parts of Scandinavia which has been a key region for dendroclimatological research. The observed annual and summer temperatures during 1901–2005 were firstly decomposed into different frequency bands using ensemble empirical mode decomposition (EEMD) method, and then the scale-dependent relationship was quantified using Pearson correlation coefficients. The relationship between the observed annual and summer temperatures determined by the instrumental data was subsequently used to evaluate 7 climate models. The model with the best performance was used to infer the relationship for the last millennium. The results show that the relationship between the observed annual and summer temperatures becomes stronger as the timescale increases, except for the 4–16 years timescales at which it does not show any relationship. The summer temperature variability at short timescales (2–4 years) shows much higher variance than the annual variability, while the annual temperature variability at long timescales (>32 years) has a much higher variance than the summer one. During the last millennium, the simulated summer temperature also shows higher variance at the short timescales (2–4 years) and lower variance at the long timescales (>1024 years) than those of the annual temperature. The relationship between the two temperatures is generally close at the long timescales, and weak at the short timescales. Overall the summer temperature variability cannot well reflect the annual mean temperature variability for the study region during both the 20th century and the last millennium. Furthermore, all the climate models examined overestimate the annual mean temperature variance at the 2–4 years timescales, which indicates that the overestimate could be one of reasons why the volcanic eruption induced cooling is larger in climate models than in proxy data.

The Dendroclimatological Potential of Willamette ValleyQuercus garryana

We develop a 341-year Oregon white oak (Quercus garryana Dougl.) tree-ring chronology in Oregon's Willamette Valley to evaluate climate-growth relationships and determine the species' dendroclimatological potential at our site and in the surrounding region. The standardized and residual chronologies exhibit significant positive correlations with previous-year April and May temperatures, inverse correlations with previous-year spring precipitation and summer PDSI, a positive correlation with current-year July precipitation and summer PDSI, and inverse correlations with current-year June temperatures. The strength of these relationships varies over time. Significant shifts in the chronologies' mean and variance align with phase changes in the Pacific Decadal Oscillation (PDO), with lower and more variable growth during the warmer, drier positive phase of the PDO over the instrumental record. The absence of similar shifts prior to the 1900s, suggests a lack of temporal consistency in the expression of PDO variability at our site. The strong crossdating at our site reflects a cohesive climate signal, and the climate analysis illustrates the potential to develop proxy data over multiple centuries. Together, these results indicate a potential to expand the network of currently available climate proxy data by utilizing Q. garryana in dendroclimatological research.

Forestry under Climate Change. Is Time a Tool for Sustainable Forest Management?

Changing climate conditions are known to influence forest tree growth response and the CO2 cycle. Dendroclimatological research has shown that the climate signal, species composition, and growth trends have changed in different types of forest ecosystems during the last century. Under current and demonstrated changes in climate variability at the geographic, regional, and local levels tree growth shows also variability and trends that can be non-stationary during time even at relatively short distance between sites. In forest planning and management, yield tables, site quality indices, age class, rate of growth, and spatial distribution are some of the most used tools and parameters. However, these methods do not involve climate variability during time although climate is the main driver in trends of forest and tree growth. Previous research warns about the risk that forest management under changing climatic conditions could amplify their negative effects. For example, changing climate conditions may impact on temperature and/or precipitation thresholds critical to forest tree growth. Forest biomass, resilience, and CO2 storage may be damaged unless forest planning and management implement the relationships between climate variability and trends of tree growth. A positive aspect is that, periods of favorable climate conditions may allow harvesting higher amount of wood mass and storing more CO2 than traditional planning methods. And, the average length of both favorable and adverse periods appears to occur within the validity period of a forest management plan. Here, we show a conceptual development to implement climate variability in forest management in the view of continuing the research.

How do trees grow? Response from the graphical and quantitative analyses of computed tomography scanning data collected on stem sections

Tree growth, as measured via the width of annual rings, is used for environmental impact assessment and climate back-forecasting. This fascinating natural process has been studied at various scales in the stem (from cell and fiber within a growth ring, to ring and entire stem) in one, two, and three dimensions. A new approach is presented to study tree growth in 3D from stem sections, at a scale sufficiently small to allow the delineation of reliable limits for annual rings and large enough to capture directional variation in growth rates. The technology applied is computed tomography scanning, which provides – for one stem section – millions of data (indirect measures of wood density) that can be mapped, together with a companion measure of dispersion and growth ring limits in filigree. Graphical and quantitative analyses are reported for white spruce trees with circular vs non-circular growth. Implications for dendroclimatological research are discussed.

New perspectives for wood anatomical analysis in dendrosciences: The GSL1-microtome

The variability of wood anatomical features in the rings of trees and shrubs is known to be dependent on multifaceted environmental parameters. The ability to determine anatomical variations over longer time periods as decades or centuries is a step forward in dendroecological and dendroclimatological research. In this regard micro sectioning is still one of the basic requirements but sectioning devices (microtomes) designed for wood anatomical purposes are rarely available. We present an affordable heavy duty, but light-weight microtome operated with removable blades. This portable device enables the production of large sections for dendroclimatological reconstructions as well as various types of common sections for wood anatomical studies.

Observed continentality in radial growth–climate relationships in a twelve site network in western Labrador, Canada

Despite their suitability for dendroclimatological research, the boreal regions of central and western Labrador remain under-researched. In an attempt to evaluate the growth trends and climatic response of this region's trees, master chronologies have been developed for its four dominant conifer species. Balsam fir ( Abies balsamea (L.) Mill.), white spruce ( Picea glauca (Moench) Voss), black spruce ( Picea mariana (Mill.) Britton, Sterns, Poggenb.) and eastern larch ( Larix laricina (DuRoi) K. Koch) were sampled systematically within a 3 × 4 grid of twelve sites at the intersection of 62°W, 64°W and 66°W longitude, and latitudes 52°N, 53°N, 54°N and 55°N. The two most dominant species at each site were sampled, yielding a total of twenty-four master chronologies, all of which reflected a highly significant common signal at each site. The chronologies were subjected to a response function analysis to determine the nature of the growth–climate relationships in the region. Summer temperature proved to be the predominant limiting factor with regard to radial growth at most sites. The onset of the optimum temperature regime, however, varies across the network of sites, revealing evidence of a gradient of continentality in the data. Growth–temperature correlations indicated a significant relationship with July temperature at most eastern sites, while western sites tended to correlate with May, June and August temperatures. Central sites tended to correlate with June–July temperatures. We interpret these results as demonstrating the bioclimatic gradient of change between coastally proximal, maritime-influenced sites and inland, continentally influenced locales. This transition occurs approximately 330 km inland from the open Labrador Sea.

A forced response to twentieth century climate conditions of two Spanish forests inferred from widths and stable isotopes of tree rings

This dendroclimatological research is based on two close pine forests (Pinus sylvestris and Pinus uncinata) located at the Northern Iberian System (Spain), and three tree-ring variables (ring widths, δ 13C and δ 18O). The climate-tree growth system was assessed at local and regional scales using three climate datasets. Calibration of tree-ring records with climate showed a diversity of information recorded in the different variables, such as a general response to temperature and precipitation of current growing period, and an important contribution of previous year conditions understood as the use of food reserves. The analysis of the stability of climate-tree growth relationships throughout the twentieth century showed a shift of those climatic variables to which trees responded and results suggested an enhancement of reserve use on current tree growth. The results obtained in this research made clear a physiological adaptation of trees to changing climate. The results provided hints that the recent warming coupled to slight precipitation decay are forcing growth of studied trees to a higher stress status and to a higher climate-growth synchronisation. These instabilities also have implications on future dendroclimatic reconstructions performed with trees growing under changing environments.