Search

Changes in the frequency, duration, and severity of climate extremes are forecast to occur under global climate change. The impacts of climate extremes on forest productivity and health remain difficult to predict due to potential interactions with disturbance events and forest dynamics-changes in forest stand composition, density, size and age structure over time. Such interactions may lead to non-linear forest growth responses to climate involving thresholds and lag effects. Understanding how forest dynamics influence growth responses to climate is particularly important given stand structure and composition can be modified through management to increase forest resistance and resilience to climate change. To inform such adaptive management, we develop a hierarchical Bayesian state space model in which climate effects on tree growth are allowed to vary over time and in relation to past climate extremes, disturbance events, and forest dynamics. The model is an important step toward integrating disturbance and forest dynamics into predictions of forest growth responses to climate extremes. We apply the model to a dendrochronology data set from forest stands of varying composition, structure, and development stage in northeastern Minnesota that have experienced extreme climate years and forest tent caterpillar defoliation events. Mean forest growth was most sensitive to water balance variables representing climatic water deficit. Forest growth responses to water deficit were partitioned into responses driven by climatic threshold exceedances and interactions with insect defoliation. Forest growth was both resistant and resilient to climate extremes with the majority of forest growth responses occurring after multiple climatic threshold exceedances across seasons and years. Interactions between climate and disturbance were observed in a subset of years with insect defoliation increasing forest growth sensitivity to water availability. Forest growth was particularly sensitive to climate extremes during periods of high stem density following major regeneration events when average inter-tree competition was high. Results suggest the resistance and resilience of forest growth to climate extremes can be increased through management steps such as thinning to reduce competition during early stages of stand development and small-group selection harvests to maintain forest structures characteristic of older, mature stands., (© 2017 by the Ecological Society of America.)

Key message This article presents ring width chronologies derived from samples extracted from historical timber buildings in the French central Pyrenees. Two chronologies for fir (Abies alba Mill.) were dated for two periods: 1446–1655 and 1679–1952 AD. These chronologies are suitable for dendroarchaeological and paleoenvironmental studies, or for reconstructing past climates. Dataset access is at https://doi.org/10.48579/PRO/KH6HPC and associated metadata at https://metadata-afs.nancy.inra.fr/geonetwork/srv/fre/catalog.search#/metadata/edba546e-3769-4f06-959b-f0d8db7fbcdb .

Old plant communities are of utmost importance for nature conservation, carbon sequestration, as well as gene pool maintenance. Shrub populations occurring in extreme environments beyond abiotic tree-lines provide diverse ecosystem services and have potential as proxy archives because they often inhabit areas with scarce and short instrumental records. We provide dendrochronological insight into one such population made up of prostrate Juniperus communis shrubs in the northern Scandinavian tundra (Norway), growing on a competition-free boulder field. We dated and provided a growth chronology of the oldest living shrub population (190 ± 148 years) from Scandinavia with the oldest individual being 683 years old. This is a conservative estimate, as shrubs in extreme environments do not form even a single row of cells in some years. The cross-dating issues of poorly growing shrubs do not fully allow to rely on climate sensitivity of the juniper population studied, although the species' potential for dendroclimatological reconstructions is generally considered high, also because the common juniper is an abundant woody species distributed globally. Old populations present an important gene source in plant recruitment, particularly in the context of the present environmental change.

Forests are pivotal for biodiversity, food webs, and human economies, and as carbon sinks their climate change mitigation potential is undisputed. However, whether trees continue to efficiently accumulate biomass at an increasing rate with age, how growth trajectories respond to climate change, and vary with latitude at species range margins is under debate. Here, we combine tree-ring data with biometric equation modeling to analyze how annual biomass increment varies according to tree age, species, latitude, and germination year. We generated 26,225 estimates of annual biomass increments for 136 individual trees, representing two evergreen gymnosperm conifer species (Picea abies (L.) H.Karst., and Pinus sylvestris L.) and two deciduous angiosperm species (Quercus spp. L. and Fagus sylvatica L.). Our dataset includes some old trees (range 150 - 405 years), and samples from locations spanning >10° latitude (55.0 - 66.3 °N) in Sweden. Annual biomass increments varied considerably between species, years and among individual trees within stands. On average, biomass increment remained positive throughout the lifespan across trees, species, and latitudes. Age-specific biomass increment was higher in the deciduous than in the evergreen species and declined with increasing latitude within species. For spruce and beech, biomass increment increased significantly with germination year, possibly reflecting faster growth in recent times in response to a warmer climate. The findings have implications for forestry practices aimed at productivity, biodiversity conservation, and climate change mitigation.

Fire is an important biophysical process in pine (Pinus) and mixed pine-oak (Quercus) forests and woodlands across the Central Appalachian Mountains. Decades of fire exclusion, however, particularly on public lands, have resulted in a well-documented homogenization of species composition and forest structure. Our objective was to inform management and restoration efforts by expanding on previous dendroecological research at New River Gorge National Park and Preserve and adjacent Babcock State Park in southern West Virginia. Specifically, we assessed pine woodland fire activity in the context of local industrial history, land management, and regional drought. Samples cut from 110 fire-scarred pine trees, distributed across four sites, were used to develop a fire-scar record that spans the period 1842–2010; however, sample depth diminishes rapidly before the 1860s. Fires occurred frequently and extensively in the early–mid 20th century, coinciding with peak coal production and population density. Eleven major fires, or years when at least two trees and 25 % of samples recorded a fire scar at an individual site, were documented in the tree-ring record, but none occurred during the federal land management era (1978–present). Synchronous fire events recorded at two or more sites were associated with drier than average September–May (‘dormant season’) climate conditions. Our results indicate that, since the late 19th century, fire activity in pine woodlands at the New River Gorge has been driven primarily by human ignitions associated with industrial activities, and that periods of drought have amplified landscape-scale fire occurrence. Land managers should consider these historical fire patterns when developing restoration strategies that may include prescribed fire, thinning treatments, and managed wildfires.

IntroductionCoastal forests occupy low-lying elevations, typically adjacent to tidal salt marshes. Exposed to increased flooding with sea level rise, coastal forests have retreated as salt marshes advance upslope. Coastal forests likely currently experience periodic tidal flooding, but whether they temporarily accommodate or quickly succumb to rising sea level under changing climatic conditions remains a complex question. Disentangling how tidal flooding and climate affect tree growth is important for gauging which coastal forests are most at risk of loss with increasing sea levels.MethodsHere, dendrochronology was used to study tree growth relative to climate variables and tidal flooding. Specifically, gradients in environmental conditions were compared to species-specific (Pinus taeda, Pinus rigida, Ilex opaca) growth in coastal forests of two estuaries (Delaware and Barnegat Bays). Gradient boosted linear regression, a machine learning approach, was used to investigate tree growth responses across gradients in temperature, precipitation, and tidal water levels. Whether tree ring widths increased or decreased with changes in each parameter was compared to predictions for seasonal climate and mean high water level to identify potential vulnerabilities.ResultsThese comparisons suggested that climate change as well as increased flood frequency will have mixed, and often non-linear, effects on coastal forests. Variation in responses was observed across sites and within species, supporting that site-specific conditions have a strong influence on coastal forest response to environmental change.DiscussionSite- and species-specific factors will be important considerations for managing coastal forests given increasing tidal flood frequencies and climatic changes.

Eighty one well-preserved wooden pillars were found аs a result of underwater archaeological excavations of a submerged prehistoric settlement in the estuary of Ropotamo River, Black Sea. That provokes a scientific interest to identify wood materials. The longest tree-ring chronologies have been used to build floating dendrochronology series. Anatomical features of xylem showed that 34 out of the 81 studied wooden pillars belong to genus Quercus. The remaining 47 pillars belong to a species of the genera Fraxinus, Acer, Ulmus and Platanus. It has been found that 8 out of 34 oak pillars have a length of tree-ring series over 30 years. This was the reason to select them for dendrochronological studies. The length of the built floating master chronology for the oaks is 84 years. The lack of strong coherent signal between 34 single oak dendrochronological series can be explained with three different types of oak forest ecosystems, in the area of the Ropotamo River estuary. These forest ecosystems are as follows: oak high stand forests in Strandzha Mountain, oak coppice forests on the Black Sea coast plains and riparian ‘Longoz’ forests of Ropotamo River. The tree-ring series of these forest types have different tree-ring signatures. Based on the tree-ring analysis it can be assumed that the timber of the above-mentioned three types of oak ecosystems was used in the construction of the prehistoric settlement.

Mixed forests play a key role in terms of stability, production potential, and adaptation to climate change. In addition, the studied Norway spruce [Picea abies (L.) Karst.] and Scots pine (Pinus sylvestris L.) belong to the most economically important tree species in Europe. The objectives were to determine the effect of the species composition of these two tree genera on the production, structure, diversity, and growth of mixed stands at lower elevations in the Czech Republic. Based on dendroecological samples, research was also carried out on the influence of climatic factors and climate change on the radial growth of these trees of interest. Mixed forests showed higher timber production by 29.8% compared to spruce and pine monocultures. The production of mature stands ranged from 328 to 479 m3.ha-1. Spruce achieved higher radial growth, but its growth variability was higher than that of pine. Compared to precipitation, temperatures had a greater influence on the radial growth of both tree species, especially in the growing season. In terms of diversity, mixed stands achieved significantly higher structural differentiation and overall diversity compared to monospecific variants. Mixed stands can achieve higher production potential, diversity, and especially resistance to climatic extremes in the lowland regions of the Czech Republic. The differences between mixed stands and monocultures, i.e. the effect of tree species mixing, depend on the appropriate proportions of tree species and their spatial pattern.

The Lagunas de Montebello National Park, Chiapas, Mexico, is one of the most important protected areas in terms of ecology and the provision of ecosystem services in the state of Chiapas; however, it lacks long-term climate information to support comprehensive plans for the conservation of endangered species and ecosystem restoration actions. The objectives of this work were to analyze: (i) the interannual variability of the annual rings of Pinus oocarpa Schiede in the Lagunas de Montebello National Park, as influenced by climate; and (ii) the ocean-atmosphere phenomena influence on both the interannual variability of the total ring-width series. A dendrochronological series of P. oocarpa was built for the period 1857-2018 (162 years), which indicates the presence of extreme hydroclimatic events in the region. Of these, the 1998 drought was a milestone for the management of this natural area due to the high-intensity fires that affected the area and caused unprecedented ecological, social, and economic damage in the site history. The climatic variables with the greatest influence on the annual radial increase of the species are precipitation and maximum temperature in winter-spring, when growth is positively associated with precipitation and negatively associated with temperature, attributed to increases in evapotranspiration. El Niño Southern Oscillation was the phenomenon with the highest correlation with climatic variability and the radial growth of the species, in frequencies of less than five years, although the positive influence of the Atlantic Multidecadal Oscillation was also assessed annually. Global warming, characterized by increasing temperature, threatens the persistence of plant communities in the study area; therefore, knowing its impact on the growth of species of economic importance is essential to support conservation actions.

Silver fir (Abies alba Mill.) is still counted among drought-tolerant tree species. However, its ability to cope with the recent extremely dry period has not yet been sufficiently studied. The objective of research was to analyse differences in the climate-growth response between silver fir, Norway spruce (Picea abies L. Karst.) and European larch (Larix decidua Mill.) growing in areas with large-scale disintegration of spruce stands. In 2019-2021, the increment cores were sampled at 16 sites along the altitudinal gradient of 340-775 m a.s.l. in different regions of the Czech Republic affected by bark beetle outbreak. The radial growth pattern of fir was compared with that of spruce or larch growing under the same site conditions. In fir, the missing rings were frequently recorded during the period of peak SO2 pollution load in 1966-1985, but they were rarely identified in recent years. In spruce and larch, missing rings were less common and occurred mainly in the recent dry period after 2015. Fir was less sensitive to summer drought compared to larch and especially to spruce, which showed high sensitivity to summer drought regardless of the altitude. The significant positive response of fir to summer precipitation was recorded at sites up to 450 m a.s.l., however, its sensitivity to drought has increased in the last two decades. Hence, when considering the wider use of fir, it is necessary to respect its ecological requirements as much as possible in order to preserve its vitality and production potential in changing climatic conditions.

The outbreaks history of the Siberian moth (Dendrolimus sibiricus Tschetveraikov, 1908) in larch forests of the forest-steppe at the eastern foothills of the Kuznetsk Alatau mountains (West of the Chulym-Yenisei basin, South of Eastern Siberia, Republic of Khakassia) is reconstructed. Outbreaks of this species have repeatedly covered forests from the Urals to the Far East on an area of more than 1 million hectares. However, there is a lack of long series of observations of changes in the size of the Siberian moth populations. Data on the history of the defoliations caused by it will at least partially fill this gap. For reconstruction, we studied the radial growth in six larch stands, which in the past were subjected to intensive defoliation by the Siberian moth. Using the OUTBREAK algorithm, specific features (abrupt, deep, and prolonged declines in growth) were found in the series of radial growth, indicating defoliation in the past. In total 31 such periods were found in 1740–2017. A study of the frequency characteristics of the chronology of defoliation showed that after the end of the Little Ice Age, the interval between defoliations gradually decreased from 10–11 years at the end of the 19th century to 7 years in the 1930s. Since the 1940s, this interval has decreased to 4–6 years, which we attribute to anthropogenic impact (massive logging and, apparently, more frequent ground fires). The consequence of this was the fragmentation of forest stands and the periodic eliminations of overwintering entomophages by fires. As a result, the frequency of occurrence of the Siberian moth foci in the study area increased either due to its escape from the control of entomophages, or because of the formation of a system of migration foci that existed at different times in fragmented forest stands.

Boreal forests are experiencing severe climatic changes that vary widely across the broad geographic distribution of the biome. The changes are greatest near the subarctic treeline where trees often exhibit high climatic sensitivity because climatic conditions approach the limits of their physiological tolerance. Despite the importance of subarctic boreal forests, the lack of field-acquired growth data remains a critical issue that limits the generalization of forest productivity models across the entire boreal biome. Using tree-ring chronologies from remote stands distributed along three latitudinal gradients ranging from 65 to 102°W, we investigated recent trends in black spruce growth and their relationships with recent climate warming near the subarctic treeline in eastern Canada. Our results show a generally positive effect of temperature and a negative effect of precipitation, both indicating that black spruce growth is temperature-limited near its northern range limit. However, we observed a strong gradient in temperature-growth coupling within a small latitudinal gradient (about one degree of latitude), where strong temperature constraints appear limited to the northernmost, coldest stands. Moreover, the positive growth response to temperature decreased from wetter to dryer sites and climate-growth coupling declined over the study period in the driest sites. These results suggest that the growth increase associated with warmer temperature may be limited by reduced precipitation and potential moisture limitation. Lastly, our results suggest that acute climatic events have the potential to induce abrupt shifts in tree climate-growth relationships. Such results indicate that the expected beneficial effect of warming on high latitude tree growth may be less generalized and more complex than previously thought in northeastern Canada, perhaps due to factors other than temperature, which might confound the climate-growth coupling southwards. Thus, our results highlight the need for a better understanding of additional growth drivers in these poorly studied regions and for physiologically informed definitions of acute climatic events, in order to refine broad-scale forest productivity modeling.

Identification of the species for dendrochronological studies is of great relevance to understand various aspects of climate change. However, in the northwestern Himalayan region, dendroclimatological investigations are confined to conifer species, with broadleaved species being disregarded. Thus, the present study was conducted to assess the growth response of seven multipurpose tree species (MPTs), namely Bauhinia variegata, Celtis australis, Grewia optiva, Paulownia fortunei, Toona ciliata, Ulmus villosa and Melia composita to local climate variables, viz. temperature as well as rainfall (seasonal, monthly, average) and CO2 level by evaluating the climatic signal in tree ring chronologies at Solan district, India (altitude 1 250 m) in the mid-hills of the northwestern Himalayas. The results indicated that only the maximum, rainy season temperature and CO2 level varied significantly (P < 0.05) between 1991 and 2017. Only G. optiva exhibited a significant (P < 0.05) tendency toward increased growth. C. australis has a remarkable negative correlation with temperature variables, viz. average, maximum, spring season, March temperature, whereas T. ciliata exhibits a positive correlation with temperature variables, such as rainy season, average and April temperature. Similarly, winter, total and December rainfall have a profound effect on P. fortunei, while March rainfall adversely affected the growth of B. variegata. On the other hand, G. optiva demonstrated sensitivity to both temperature (February and May) and rainfall variables (winter, February and May). U. villosa recorded a positive correlation with rainfall (autumn and October rainfall) but a negative correlation with temperature variables (maximum and April temperature). Elevated CO2 levels affected only two species (G. optiva, M. composita) out of the seven selected species. Our findings will contribute to a better understanding of the climate growth relationships of investigated tree species, as a result, to more accurate projections of the effects of climate change on these MPTs and directing future studies.

Historical information on wildfires and dendrochronological studies offer meaningful clues about fire and climate regimes, factors that affect forest structure and dynamics. This study aimed to determine the effect of fire history on vegetation dynamics and successional pathways of areas under different fire management policies in the Lagunas de Montebello National Park (LMNP), Chiapas, México. The selected study sites were El Parque area under fire exclusion policies since 1961; Tziscao-inhabited area under fire prohibition since 1984; and Antelá area with a traditional agricultural fire management history. A Pinus oocarpa ring-width chronology was used as a proxy for climate variability to which wildfire occurrence was mapped and to determine the establishment patterns of this dominant species. Current vegetation composition and structure and fuel loads were determined to characterise the study sites. Large wildfires, like those occurring in 1984 and 1998, were associated with periods of high humidity followed by intense droughts; they were linked to strong El Niño events and severely impacted the LMNP. Vegetation dynamics indicated simplification of mesophyll forest (climax) to pine-oak-sweetgum forests, with Pinus dominating the overstorey in all sampling sites. Pine, oak and sweetgum species were the dominant juvenile trees in Antelá, El Parque and Tziscao, respectively. Late-successional seedlings (i.e., Prunus) were present in Antelá and El Parque, while were absent from Tziscao where several wildfires had occurred. Fuel accumulation in sites within protected areas subject to fire exclusion policies was very high (40-68 t ha-1); in contrast, it was the lowest in rural Antelá (24 t ha-1). Considering vegetation vulnerability to wildfires associated with extreme humid-dry climate events, increased fire hazard due to fuel accumulation, and the socio-ecological impacts of these events, we recommend revising the fire exclusion policies currently implemented in the LMNP and applying an integrated fire management approach that incorporates local socio-ecological conditions.

Central Anatolia is one of the semi-arid regions of Turkey that does not offer very suitable conditions for the growth of trees. Tree growth is a process controlled by genetic, environmental and climatic factors. Trees record these signals, which provide valuable scientific data for dendrochronological research. We used raw annual tree-ring width (taken from trees under the age of 100 years) as one of the dendrochronological parameters to compare Juniperus foetidissima and J. excelsa in terms of affecting factors. We compared the annual tree-ring width of both species considering species, locations and research sites of the altitude range of 677-1 400 m a.s.l.. Environmental signals (longitude and latitude, altitude, slope, exposure, human impact and nearest settlement distance), as well as climatic factors (precipitation, temperature, moisture) affecting growth were examined. Results indicate that there is an obvious difference in raw annual tree-ring widths depending on species. J. foetidissima differs from J. excelsa in wider annual tree-ring widths and preferences to a low slope and altitude. While the annual tree-ring width of J. excelsa did not respond to the environmental signals, the annual tree-ring width of J. foetidissima was notably correlated with longitude, latitude, altitude and slope. The most remarkable variables affecting the growth of both species were summer temperatures and moisture.

Trees can contribute to the reduction of atmospheric CO2 concentrations, but they do so at varying rates. The carbon sequestration rate (CSR) of trees is influenced by many factors including tree age, forest density, site conditions, and extreme events such as droughts and floods. This research reconstructs past carbon stocks of Pedunculate oak (Quercus robur) trees in floodplains with different hydrological conditions (low and high active floodplain, the seepage water zone of the former floodplain, and the tributary floodplain). We used increment tree cores and allometric equations and compared the annual changes in stocks as a way of assessing CSR. Furthermore, we used time series data on floods and droughts to analyze possible effects of extreme events on CSR. The aims of this study are to (a) compare the CSR of dominant Q. robur in young plantations to dominant trees in old forest stands, (b) compare the CSR of old Q. robur trees under different hydrological conditions, and (c) analyze how drought and flood events influence the CSR of Q. robur in different hydrological conditions. From 2009 to 2018, old Q. robur trees on the low active floodplain had an average CSR of 18.4 ± 1.1 (SE) Kg tree−1 year−1, while young trees had an average CSR of 8.7 ± 0.6 (SE) Kg tree−1 year−1. From 1976 to 2018, the overall CSR of Q. robur was highest on the high active floodplain (18.6 ± 1.7 (SE) Kg tree−1 year−1) and lowest on the seepage water zone of the former floodplain (13.1 ± 1.1 (SE) Kg tree−1 year−1). CSR was higher during flood years in all hydrological conditions, but was significantly reduced by drought only on active floodplains with a comparatively high elevation. Floodplains are well-suited areas for reforestation as natural climate solutions because the dominant trees in these areas have a high CSR even under severe conditions which are predicted to become more common with climate change in the future.

An interdisciplinary approach has been developed for a comprehensive study of the restoration (increase) of the tree-line border. In essence, the approach is a detailed scheme in eleven steps, which can have universal application in the study of processes in the tree-line border in all mountains in Bulgaria, regardless of their specifics. The ideological basis of the campaign is the combination of specific scientific methods, such as geographic information systems (GIS methods), silvicultural methods and dendrochronological methods. The flexible, combined use of these scientific methods leads to overcoming the one-sidedness in the independent application of each of the methods and provides completeness and comprehensiveness of the scientific picture in the study of the tree-line border dynamics. [ABSTRACT FROM AUTHOR]

It is identified that since the beginning of the 19th century, the degradation of pine stands has acquired a huge scale on all continents. In Ukraine, according to the Ministry of Environmental Protection and Natural Resources of Ukraine, the average annual temperature has increased by more than 2°C since the beginning of the 20th century, in particular, by 1.2°C for the last 30 years. In recent years, the number of days with maximum summer temperatures is more than 35°C and 40°C has almost doubled, meaning the extreme weather events are intensifying. In most parts of Ukraine, there is already a tendency to increase droughts and fire danger, repeating the years during which plantings will be exposed to water stress, pest damage, and degradation of forest ecosystems in general due to the increase in the number and duration of hot periods. It was determined that dendrochronological methods are used to investigate the relationship between climate change and radial pine growth. The main methods for investigating radial increment are to take cores at a height of 1.3 m from two opposite radii, to exclude the influence of random factors on the radial increment. The width of year rings is determined using installations for dendrochronological studies, with automatic data recording. These values of annual rings are processed according to the programmes of the International Tree Ring Data Bank (ITRDB). A specialised COFECHA programme is used to synchronise the series with setting the calendar year of formation of each year’s growth. It was identified that the growth of Scots pine is limited by the humidification of the climate and the presence of sufficient moisture in the soil, but in the case of extreme temperatures, a negative trend towards drying out of plantings still remains

The dendrochronological climate signal of Norway spruce (Picea abies), European larch (Larix decidua), and European beech (Fagus sylvatica), among others, depends on altitude, therefore we have to collect dendrochronological data systematically for each species along altitude gradients. To this end, we established local tree-ring chronologies for the three species along two elevation gradients: (1) Kokra – Jezersko with sites at 750, 780, 950, 1200, 1250, 1380, 1600 m a.s.l., and (2) Bled – Radovna – Krma with sites at 518, 550, 580, 700, 750, 900, 950, 1000, 1200, 1400, 1600, 1760, 1900, 2040 m a.s.l. We present the main characteristics of the chronologies and the results of the dendroclimatological analyses, which show how the climatic factors influence the variation of the tree rings in dependence of altitude and species. We also present the agreement of the different chronologies in terms of standard dendrochronological parameters such as the t-value and discuss the potential use of the presented database.

Dendrochronological potential of conifers from Ayubia National Park, Pakistan was determined. A total of four conifer species (Abies pindrow (Royle ex D. Don), Cedrus deodara (Roxb. ex D. Don), Pinus wallichiana A.B. Jacks. and Taxus baccata L.) were studied from different elevations. Comparative analysis of DBH-growth rate and DBH-age were performed among the species with maximum age showed by A. pindrow of 456 years with 0.01 cm/year growth rate. P. wallichiana was found to be fast growing with 0.05 cm/year growth among other species while C. deodara trees were having the strongest correlation between their age and DBH values (R2= 0.9225). Quality of cross dating and accuracy of tree ring measurements was checked by COFECHA. Mean sensitivity of all species ranges from 0.265 to 0.328 with auto-correlations range from 0.562 to 0.712 which specified the dendrochronological significance of these conifers. ARSTAN program was used for autoregressive modeling to remove any possible variance other than climatic disturbance and to standardize the tree ring chronologies. Tree-ring variations were evident among all the cores possessing distinct wide and narrow fluctuations of ring growth with A. pindrow (Avg. mean ring width = 1.46 mm) and T. baccata (Avg. mean ring width = 1.80 mm). All the conifer species showed good climatic signals in their tree ring measurements and are valuable for the dendroclimatic growth response investigations.

The annual tree increment is one of the integral indicators of abiotic and biotic processes occurring in the forest ecosystem. The use of logistic regression models based on annual tree-ring growth data is a promising approach to studying tree mortality. The diversity of logistic variables in scientific research is a result of various choices of statistics (average, median, growth trend, etc.) and their score in the time-window for the past N (5, 10, ..., 40) years. We propose a new scheme for the formation of logistic variables that involves fixing the statistics for calculating the average and choosing two non-intersecting time-windows based on measurements of the annual tree-rings growth. The choice of non-overlapping «windows» enables setting the ratio of the average growth of annual rings of trees between the windows for different periods of time. We examined the past 41 years of tree growth. Logistic regression models are constructed on a set of pairs of non-intersecting «windows» with a limit on the values of the sensitivity and specification of at least 1.6. The calculation of the percentage prediction if a tree is living or dying was done based on the contingency table in the logistic regression model. The logistic regression models were visualized using ROC curves. The models were compared on an expert scale based on the calculated area under the ROC curves. The obtained logistic regression model was verified by the bootstrap method. The calculations were carried out for the Siberian stone pine Pinus sibirica du Tour growing in the Baikal region (the Khamar-Daban Ridge) using the R programming language. The computed logistic regression model helped us predict live and dead trees in more than 80 % of cases.

Millennial-length tree-ring width chronologies are used to reconstruct temperature and place recent warming into historical context. The Simplon valley in the Western Central Alps is an ideal region for such a study as it provides historical timber back to medieval times which can be combined with temperature sensitive living larch trees. However, the exact provenance of the historical timber is unknown, but might origin from different elevations which potentially biases derived temperature reconstructions. To study the effect of elevation on tree growth and climate sensitivity, approximately 250 trees at three elevational levels (1500, 1700, and 2000 m a.s.l.) were sampled. Results indicate that the overall growth rate decreases with increasing elevation. Significant correlations between tree-ring width and summer temperature are recorded at tree sites ≥ 1700 m a.s.l. The comparison of the growth patterns between living trees and historical timber from Simplon Village (1476 m a.s.l.) reveals a most likely origin of the historical samples between 1700 and 2000 m a.s.l. When combining the data from the living trees at the different elevational levels with the historical timber, to produce three separate chronologies spanning the past 1200 years, substantial low frequency differences are recorded after RCS detrending the data. This finding demonstrates that the origin of samples in combined (living + historical) chronologies has a strong influence on long-term summer temperature reconstructions. It is thus important to analyse the growth characteristics of historical timber, and estimate their provenance in comparison to living trees, when producing millennial length chronologies.

This paper explores the history of age detection of trees, especially the age history of oak trees, throughout two centuries in Estonia. It was already in the beginning of the 19th century when relations between the size and age of oaks in northern Latvia (previous Livonian province) were described. The paper explains how the species concept of Quercus robur developed over time in the past and points out discussions on the existence of two varieties Q. robur L. var. tardiflora Czern and Q. robur L. var. praecox Czern. It also states that thanks to the use of the increment borer, the first dendrochronological studies were carried out in Estonia in the 1920s. Dendrochronological research in the Soviet Union began in the 1950s with Lithuania being the leading country in the field headed by Teodaras Bitvinskas. In Estonia, research was continued in the 1960s until now. The paper takes a look at the life of Mart Rohtla who introduced the method of determining tree age according to tree bark, presents his standpoints on oaks and critically assesses these. A comparative assessment is given on the ages of oak and lime trees found according to the tree-ring method and bark increment method. The great ages of the oaks and limes found by applying the bark increments method are doubted and considered unreliable. However, the age of the surface layers of the bark of oaks and limes needs clarification in the future.

As currently framed, the forest cycle model that underlies close-to-nature management in temperate beech forests throughout the globe specifies an orderly sequence of temporal development within even-aged patches comprising the forest mosaic. Although this model has been widely applied to European beech (Fagus sylvatica L.) forests, the underlying assumptions of disturbance-induced even-agedness (i.e., within-patch age homogeneity) and competition-induced size differentiation (i.e., within-patch size heterogeneity) have not been tested in natural beech forests due to prohibitions on tree coring in primeval forest reserves. In a rare and unprecedented test dataset of spatially explicit tree ages in an old-growth European beech forest, we employed triangulated irregular networks of Delaunay triangles to objectively identify natural tree neighborhoods to determine if neighboring (i.e., within-patch) trees were even- or, at most, two-aged. Age differences among neighboring trees (summarized in 25-yr age classes) were rarely 50 yrs, while the few "even-aged" patches were very small (100 m2) and relatively young (

The present study illustrates the situation of the genus Abies in the Mediterranean and in Greece, focusing in detail on the oromediterranean forest of the southern Peloponnese, at Mt. Taygetos. The existing pattern of forest dynamics (mosaic cycle) and also the timberline dynamics are presented and explained. Since fir forests are highly susceptible to drought-related impacts (fire and fir dieback: insect outbreaks/ forest pathogens), the analysis of the present situation is put into perspective by looking at the role of direct human influence and the climatic fluctuations of the past, taking into consideration dendrochronological findings and archival climate records. In view of climate warming the question is whether in recent decades the fingerprints of climate change can already be observed in the Greek fir forests. The study concludes that drought periods and climatic extremes have been an essential part of Greek climate for many centuries, causing high natural forest vulnerability. Therefore, fir dieback and fires are not a new phenomenon either – but in recent decades the accumulation of fuel, caused by land abandonment, has increased the danger of large wildfires. Nevertheless, the Greek mountain forests are highly endangered by increases in aridity and/or more frequent climate extremes (heat waves), together with increased risk of wildfires. Recommendations for an active forest management (counteracting expected adverse effects of climate change, by focusing on the establishment of an Abies cephalonica Loudon /Pinus nigra J. F. Arnold mosaic cycle) and further scientific research are provided.

Tree-ring growth of forest trees is closely related to climate and environment changes during growth period, thus it is able to provide precise information on climate changes. Therefore, the current study is intended to estimate growth changes and to develop an estimating formula for ring-growth based on climate factors for Quercus mongolica. The tree-ring data used are from the 5th national forest inventory conducted nationwide, with climate data in a raster format from the Korea Meteorological Administration. Using dendroclimatological method, summary statistics were obtained through cross-dating and standardization, and tree-ring chronology was written. The findings indicate that the variation and fluctuation in the tree-ring growth index are the outcome of complicated effects of diverse climate factors including temperature and precipitation. Also, significant annual variance for Q. mongolica has been observed, with the decreasing temperature efficiency index for it, so that the temperature condition for its growth is getting worse. The statistical analysis to estimate the relationship between tree-ring growth and climate factors is expected to contribute to evaluating changes in productivity which will be affected by climate change in the future.

Old-growth forests in the Pacific Northwest are being fundamentally altered by climate change. A primary example of this is yellow-cedar (Callitropsis nootkatensis), a culturally and economically important species, which has suffered widespread decline across its range since the beginning of the twentieth century. We used tree rings to compare the climate-growth response of yellow-cedar to two co-occurring species; western hemlock (Tsuga heterophylla) and Sitka spruce (Picea sitchensis), in an old-growth forest on Haida Gwaii, Canada, to better understand the unique climatic drivers of a species that is declining across its range. We developed three species-specific chronologies spanning 560–770 years, reconstructing a long-term record of species growth and dynamics over time. The climate is strongly influenced by the Pacific Decadal Oscillation (PDO), a multi-decadal pattern of ocean-atmospheric climate variability. Climate varied across three time periods that have coincided with major shifts in the PDO during the twentieth century [1901–1945 (neutral/positive), 1946–1976 (negative) and 1977–2015 (positive)]. Conditions were significantly warmer and wetter during positive phases, with the greatest maximum temperatures in the most recent period. We used complimentary methods of comparison, including Morlet wavelet analysis, Pearson correlations, and linear-mixed effects modeling to investigate the relations between climate and species growth. All three species exhibited multi-decadal frequency variation, strongest for yellow-cedar, suggesting the influence of the PDO. Consistent with this, the strength and direction of climate-growth correlations varied among PDO phases. Growing season temperature in the year of ring formation was strongly positively correlated to yellow-cedar and western hemlock growth, most significantly in the latter two time periods, representing a release from a temperature limitation. Sitka spruce growth was only weakly associated with climate. Yellow-cedar responded negatively to winter temperature from 1977 to 2015, consistent with the decline mechanism. Increased yellow-cedar mortality has been linked to warmer winters and snow loss. This study provides new insights into yellow-cedar decline, finding the first evidence of decline-related growth patterns in an apparently healthy, productive coastal temperate rainforest.

We present the results of a dendrochronological study and radiocarbon dating of the wooden piles of the bridge over the Drava River in Ptuj. The piles, together with stone elements (a fragment of an imperial building inscription and parts of the architectural decoration) were retrieved from the riverbed in 1913 and are now in the Regional Museum Ptuj - Ormož. Using dendrochronology, radiocarbon dating of carefully selected annual rings in the wood and calibration with the wiggle-matching method, the date of the last (outermost) annual ring on the pile was determined to be 161 ± 27 cal AD (1σ) or 160 ± 32 cal AD (2σ). Since the pile contained no sapwood, the dating approximately agrees with the date of the building inscription on the stone slab, which attributes the commission for the reconstruction or construction of the bridge to Emperor Hadrian in the last years of his reign (117-138 AD). The dating of the wood has thus confirmed that the remains examined do indeed belong to a Roman bridge, probably built or renovated during the reconstruction of the road network in the area of the colony of Poetovio under Hadrian or one of his successors.

Prof. Dr. Dieter Eckstein (1939-2021) was a leading scientist, teacher, mentor, leader, promoter and motivator in the field of dendrochronology and wood biology. After graduating in wood science and receiving a PhD in dendrochronology, he was professor of wood biology at the University of Hamburg. From 1995-2004, he was Director of the Department of Wood Biology, University of Hamburg, and of the Institute of Wood Biology and Wood Protection at the Federal Research Centre for Forestry and Forest Products in Hamburg, Germany. His work had a decisive influence on the development of wood anatomy, wood biology and dendrochronology and his laboratory was a reference point for dendrochronology worldwide. He supported dendrochronologists throughout Europe and around the world in their pioneering work to establish dendrochronology laboratories and develop dendrochronology in numerous countries, including Slovenia.

As atmospheric carbon dioxide concentrations continue to rise and global temperatures increase, there is growing concern about the sustainability, health, and carbon sequestration potential of forest ecosystems. Variable retention harvesting (VRH) has been suggested to be a potential method to increase forest biodiversity, growth, and carbon (C) sequestration. A field trial was established in an 88-year-old red pine (Pinus resinosa Ait.) plantation in southern Ontario, Canada, using a completely randomized design to examine the response of tree productivity and other forest values to five harvesting treatments: 33% aggregate retention (33A), 55% aggregate retention (55A), 33% dispersed retention (33D), and 55% dispersed retention (55D) in comparison to an unharvested control (CN). In this study, we explored the impacts of VRH on aboveground stem radial growth and annual C increment. Standard dendrochronological methods and allometric equations were used to quantify tree- and stand-level treatment effects during a five-year pre-harvest (2009–2013) and post-harvest (2014–2018) period. Tree-level growth and C increment were increased by the dispersed retention pattern regardless of retention level. At the stand level, the total C increment was highest at greater retention levels and did not vary with retention pattern. These results suggest that the choice of retention level and pattern can have a large influence on management objectives as they relate to timber production, climate change adaptation, and/or climate change mitigation.

The Mongolian Altai is an ecologically sensitive region in Central Asia where changes in climate and anthropogenic activities have a strong impact on the forest-steppe vegetation. We combine high-resolution data (pollen, non-pollen palynomorphs (NPP), charcoal) of two new sedimentological archives from the Altai Tavan Bogd National Park with dendrochronological analyses on Larix sibirica trees to study climatic changes and human landscape interactions over the last 1,350 cal yr BP. Multi-proxy palaeoenvironmental reconstructions show that the present landscape is a result of both short- and long-term climatic variations and of locally different land use. Combined evidence suggests that in the period from 1,350 to 670 cal yr BP western Mongolia was impacted by a rather cold and dry climate, followed by an episode of improved warmer and wetter climatic conditions from 670 to 400 cal yr BP. From around 400 to 200 cal yr BP, the Little Ice Age influenced the forest-steppe vegetation in the area, favoring an expansion of steppe vegetation. Over the last 70 years, climatic conditions were characterized by markedly high summer temperatures. NPP data reveal periods of increased grazing activities in the forests especially during unfavorable climatic periods. During the late 20th century, a decreasing deposition of coprophilous fungal spores with a simultaneous slight decrease of Larix sibirica forest suggest that economic timber harvesting seemed to be of more significance for forest degradation than pastural activities.

Siberian silkmoth (eggar) Dendrolimus sibiricus Tsch., (1908) is one of the most dangerous forest pests in the Republic of Tyva. Outbreaks of this phytophage in the republic occur frequently and cause significant damage to forests. Studies in Tyva were initiated by A. I. Cherepanov, N. G. Kolomiets, N. F. Reimers and others in the 50–70s of the XX century. They described the phenology of the Siberian silkmoth, the biological and ecological aspects of its life activity. In this paper we tried to summarize all the accumulated knowledge of the Siberian silkmoth in Tyva. The chronology of the Siberian silkmoth outbreaks was restored using the collected and analyzed data. We demonstrate that outbreaks of the Siberian silkmoth in the Republic of Tyva are most frequently observed in the forests of Shagonarsky, Chadansky and Turan forestry districts. On the whole, five outbreaks were registered: in 1954–1966, 1969–1975, 1979–1985, 1997–2000, and in 2009–2011. Duration of the outbreaks was 13–7–7–4–3 years and the intervals without outbreaks were 2–1–2–1 years. The fragmented character of the obtained data on outbreaks shows the need for their verification by dendrochronological methods. Valid analysis of data is possible with the use of control tree species not susceptible to the Siberian moth damage and some parameters of the annual rings, for example, optical density of the wood.

This study was carried out in the oriental beech communities in order to investigate the natural regeneration and assessment of radial growth trend from 1960 to 2016. In each area, 50 1000-m2 circular plots were established based on a random-systematic method. Regeneration was sampled on two concentric circles with an area of 20 and 10 m2 of the sample plot center (for seedling and sapling, respectively). Then, 160 core samples were taken from selective trees by increment. The results of harvested stand indicated that natural and human disturbances regimes lead to change in the diameter distribution, age distribution, radial growth pattern and establishment of tree's regeneration. In the unharvestedarea, sapling of F.orientalis and seedling of Carpinus betulus and Acer velutinum had the highest density. Whereas, the seedlings of F.orientalis and C.betulus were dominate in the harvested stand. During the studied period, 324 tree species were established in the unharvested area and the highest frequency of tree recruitment was belonged to 1970-1980 decades. However, in the harvested stand, 262 tree species were established and the greatest frequency was recoreded from 1960 to 1970 years. The radial growth of trees in the harvested area showed the higher variations during the studied period and the highest frequency of release events was belonged to moderate releases. Therefore, this stand should be managed in order to return their historical composition and structure, maintaining natural regeneration and the optimal development of stand for future.

Background and Purpose: Although organized forestry has existed in Croatia for more than 250 years, this mostly entailed state forests. During the last decade, Extension Services have started to support the development of forest management plans for privately owned forests. Lately, FMPs have been developed for nearly 3/4 of privately owned forests in Croatia. During the creation of those plans, yield tables and normal models for state-owned forests, primarily even-aged stands with long-time management, were used because similar data was not developed for uneven-aged and poorly managed forests. This research encompasses privately owned forests in the Croatian Mediterranean and sub-Mediterranean regions where holm oak (Quercus ilex L.) and downy oak (Quercus pubescens Willd.) are the prevailing species in forest stands. The main goal was to determine site indices revealed in the analysis of yearly radial increments and to create relevant yield tables. Materials and Methods: In this study, 1286 oak trees were cored to the centre on 377 locations spread in privately owned forests in Croatian Mediterranean and sub-Mediterranean regions. The ratio of trees and locations was approximately 3:1 for Q. pubescens. Some cored trees were more than two centuries old. After the standard sample preparation for dendrochronological analysis, cores were scanned, and tree-ring widths were determined. In total, ring width for over 67,000 rings was determined and measured. Results: Based on the data dispersion of cumulative tree increments at 40 years of age, 2 site index classes for Q. ilex and 3 for Q. pubescens were created based on k-means clustering. Prodan’s growth function was fitted to the created clusters to determine the site’s “model” tree. For the model trees, the percentage of volume growth was calculated. For easier field site index determination, height curves based on field data for each site index were calculated. Conclusions: For the first time in Croatia, systematic and controlled data on the growth (and age) of uneven-aged privately owned forests in the Croatian Mediterranean and sub-Mediterranean area were collected. Based on the data collected in the field, three different site indices for downy oak and two site indices for holm oak were determined. These results could find their application during operational forest management and forest exploitation because they allow for more accurate determination of the site production strength in the explored stands.

Climate change-driven Dendroctonus ponderosae outbreaks in semi-naïve Pinus albicaulis may result in rapid natural selection for trees with genotypes and phenotypes associated with survival. In this study, we investigated whether survivors were genetically and chemically different from a living cohort of trees that escaped predation due to smaller size and estimated genetic diversity. We also examined how growth rate and climate sensitivity varied between beetle-killed and surviving trees. Dendroctonus ponderosae predominantly kills large diameter trees; therefore, we predicted that large surviving trees would have distinctive genetic profiles and, due to bottlenecking and drift, survivors would have lower genetic diversity than the abundant smaller mature trees that escaped predation. We found survivors were indeed genetically divergent from the smaller trees but, contrary to expectations, the smaller trees had lower diversity. This suggests that while beetles may select for trees with particular genotypes, other factors are also driving population genetic sub-structuring. Individual tree terpene profiles were diverse and varied by population but showed no clear relationship to survivorship. Two groups of trees with divergent sensitivities to climate were observed in each population, but neither was a clear indicator of survivorship or susceptibility to beetle attack. Growth rate was the best predictor of survivorship with survivors growing significantly slower than beetle-killed trees over their lifetimes although growth rates converged in years just prior to increased beetle activity. Overall, our results suggest that P. albicaulis forests show considerable divergence among populations and within-population genetic sub-structuring, and that they may contain complex mosaics of adaptive potentials to a variety of stressors including D. ponderosae. To protect the ability of this tree to adapt to increasing pressure from beetles, blister rust, and climate change, a top priority should be the maintenance of standing genetic diversity and adaptive shifts in allele frequencies.

At the end of 2020, Prof. Dr. Katarina Čufar received two prestigious awards: the Zois Prize for important scientific research achievements in the development of dendrochronology and wood science, which is a state award of the Republic of Slovenia, and Golden Plaque from the University of Ljubljana for outstanding scientific research, exemplary teaching and achievements in enhancing the university’s reputation. We briefly introduce the prize-winner and her work.

Painted chests are an important part of museum collections of folk art in the Alpine region. At the Gorenjska Museum in Kranj, we examined over 30 chests mostly made of Norway spruce (Picea abies) and selected 18 of them for dendrochronological analysis. We took high resolution images of the radial boards of the constructional parts of the chests for tree-ring analyses. We constructed tree-ring chronologies for each of the 18 chests. Nine of them were dendrochronologically dated (eight spruce chests and one silver fir) with the end dates ranging from 1742 to 1882. The study of the chest made of silver fir (Abies alba) is presented in detail. Half of the chests could not be dated, mainly due to the low number of tree-rings or large variability of tree-ring signal of spruce in Slovenia and consequently lack of adequate reference chronologies. The results show that dendrochronology can be used to determine age and obtain information about chests that cannot be obtained from other sources.

Prof. Dr. Fritz Hans Schweingruber (29 February 1936 – 7 January 2020) was a key wood anatomist and dendrochronologist, teacher and organiser of summer field schools, who established an extensive network of scientists, wrote key books, contributed to the construction of publicly accessible databases, popularised and revealed unimaginable possibilities for the development and use of wood anatomy and dendrochronology. He established an intellectual legacy that will inspire his followers around the world for a long time to come.

Drought, coupled with rising temperatures, is an emerging threat to many forest types across the globe. At least to a degree, we expect management actions that reduce competition (e.g., thinning, prescribed fire, or both) to improve growth of residual trees during drought. The influences of management actions and drought on individual tree growth may be measured with high precision using tree-rings. Here, we summarize tree-ring-based assessments of the effectiveness of thinning and prescribed fire as drought adaptation tools, with special consideration for how these findings might apply to dry coniferous forests in the southwestern United States. The existing literature suggests that thinning treatments generally improve individual tree growth responses to drought, though the literature specific to southwestern coniferous forests is sparse. Assessments from studies beyond the southwestern United States indicate treatment effectiveness varies by thinning intensity, timing of the drought relative to treatments, and individualistic species responses. Several large-scale studies appear to conflict on specifics of how site aridity influences sensitivity to drought following thinning. Prescribed fire effects in the absence of thinning has received much less attention in terms of subsequent drought response. There are limitations for using tree-ring data to estimate drought responses (e.g., difficulties scaling up observations to stand- and landscape-levels). However, tree-rings describe an important dimension of drought effects for individual trees, and when coupled with additional information, such as stable isotopes, aid our understanding of key physiological mechanisms that underlie forest drought response.

We used the Confocal Laser Scanning Microscope (CLSM) Olympus LEXT OLS5000 for non-destructive observation and image analysis of wood anatomy traits in growth layers of tree species from different climatic zones. In European beech (Fagus sylvatica), where tree rings can generally be recognised, we discuss the changes in tree-ring structure due to adverse effects (insect attacks). Growth layers in Mediterranean Aleppo pine (Pinus halepensis) from south-eastern Spain are not always annual and contain numerous intra-annual density fluctuations (IADFs). Ocote pine (Pinus oocarpa) growing at high elevation in Honduras showed growth layers with clear growth ring boundaries and IADFs. In both pines, CLSM allowed us to recognise and measure tracheid parameters to define density fluctuations. In tropical true mahogany (Swietenia macrophylla) from Venezuela and cedrela (Cedrela odorata) from Costa Rica, we studied the growth layers with variable dimensions of vessels demarcated by marginal axial parenchyma.

Trees respond to environmental and climatic changes during their biological life. Tree rings study is one way to discover these responses called dendrochronology. The most effective climatic factors which affect tree rings are temperature and precipitation. Present study aimed at investigating the influence of temperature and precipitation on annual growth of oriental beach (Fagus orientalis Lipsky) and oak (Querscus castaneifolia C.A. Mey), which clearly illustrate climatic factors on their tree rings. Trees were selected in three altitudes (450, 900 and 1380 a.s.l), from forest part 2 of Neka and Haft Khal in central Alborz mountains of Iran. Core samples were extracted from two sides of trees with an increment borer. Growth rings widths were measured by using LINTAB6 table with accuracy of 0.1 mm. The measurement results were analyzed using time series analysis software TSAPWin. Results showed that growth pattern of oak and beech in three altitudes were not similar. Altitudes affect mean growth of these species significantly. In each altitude, oak and beech have shown different responses to temperature and annual precipitation. These differences could be depending on species’ nature. In response to climatic factors, oak was more sensitive than beech. In high altitude, previous growth season temperature of affect oak chronology negatively while had positive effect on mid and low altitudes. In all altitudes, oak positively affected by precipitation of June (of current growth year). Beech of high altitude showed positive correlation with March and summer precipitation. However, no significand correlation was detected in beech in low altitude.

Climate-growth relationships in forest trees are increasingly the focus of research aimed at understanding and assessing responses to climate change. Many studies have been confined to annual radial growth at breast height as an easy-to-measure dendrological standard variable, although its validity as a proxy for overall annual growth patterns in trees has scarcely been addressed. In this study, we test this hypothesis by exploring additional information on climate-growth relationships as well as analyzing both the radial growth at different stem heights and the height increment. For this purpose, past annual radial growth and shoot elongation were measured in 10 dominant Pinus pinaster Ait. trees in a 130-year-old stand. Radial increments were measured on disks taken from five different trunk heights up to 15 meters. Height increments were obtained by measuring the distance between consecutive branch whorls, which appear as knots after sawing a longitudinal section of the stem. The relationships between climate and both radial growth and height increment were analyzed through Pearson’s correlations and the response to extreme climatic episodes was analyzed using resilience indices. Results revealed that the climatic variables affecting growth were different for height and stem diameter. Additionally, in the case of stem diameter, the climatic variables affecting growth also depended on the height at which the sample was taken. Precipitation prior to bud break, both in the year in which the studied shoot elongation takes place and in the previous year, has a positive effect on height increment. Radial growth in the upper part of the stem was mainly influenced by spring temperatures and precipitation, whereas in the case of basal radial growth it was the autumn and winter temperatures and precipitation of the previous year to growth which had the greatest influence. Similarly, severe droughts cause greater decline in height increment, while the decline in radial growth of the upper part of stem is smaller than that of radial growth at breast height. In conclusion, the analysis of height increment and upper radial growth provides important information to complement the dendroclimatology data for radial growth at breast height, thus improving our understanding of the impact of climate change on tree growth.

During archaeological excavations on wet sites in the area of the ancient Roman Nauportus (today’s Vrhnika, Slovenia) in 2005, preserved parts of various wooden structures were discovered. We collected and investigated almost 500 samples of wood from these. Half of the samples were silver fir (Abies alba) and oak (Quercus sp.). In particular, we focused on the dendrochronological investigation of three barrels made of silver fir wood, which were used to consolidate the walls of the three water wells. First, we constructed and dated a silver fir tree-ring chronology with the help of teleconnection. Afterward, we dated the barrels with the end dates: barrel 1 – end date 10 AD, barrel 2 – end date 3 AD, and barrel 3 – end date 10 AD. All dates represent the terminus post quem, after which the barrels were made and used for wells. The time frame for the construction of wells was complemented by the dates we obtained by analysing archaeological finds on the same site. The barrels from Nauportus were compared with contemporaneous barrels from water wells recently excavated in Emona (today’s Ljubljana, Slovenia). The barrels are among the first successfully dendrochronologically dated wooden remains from the 1st Century AD in Slovenia. They will allow for the better dating of stratigraphic archaeological layers, construction phases and individual archaeological finds in the wider area south of the Alps in the period soon after it was occupied by the Romans.

In many regions, alien conifers have spread widely at lower elevations and are increasingly found colonizing alpine areas. Although studies have addressed conifer invasions at low elevations, little is known about the rates and constraints on spread into higher elevations. Here, we assess the relative importance of climate and the availability of regeneration microsites on the establishment of the alien species Pinus contorta into a high elevation site in New Zealand. Spread has occurred from two stands planted at the elevation of the native treeline (1347–1388 masl) in the 1960s. Most stems established between 1350 and 1450 masl and P. contorta individuals were found up to 270 m above the original plantings. Although the population has increased by 180% in the last 20 years, population growth rate has been declining. Furthermore, comparisons with studies from other mountain ranges around the world and at low elevations in New Zealand suggest this is a relatively limited spread. Our results suggest that climate variation did not have a significant effect on establishment patterns, as opposed to availability of regeneration microsites. Soil and alpine mat microsites favoured establishment of P. contorta and, although these microsites did not appear to be saturated, microsite availability may be an important limiting factor for the spread of P. contorta. Thus management strategies should focus on preventing spread in addition to removing already established stems.

Background and Purpose: Valonia oak (Quercus ithaburensis subsp. macrolepis (Kotschy) Hedge & Yalt.) is an east Mediterranean endemic, xerothermic and deciduous tree of particular interest in forestry. There has been a growing demand lately to include the species in reforestations in Greece which also increased the interest to investigate its response to climate change. The main purpose of this research is to study valonia oak from a dendrochronological – dendroclimatological point of view within its Mediterranean distribution range. Materials and Methods: Sampling took place in characteristic valonia oak stands where cross sections or tree-cores were taken from 40 trees. The cross sections and the tree-cores were prepared and cross-dated using standard dendrochronological methods and tree-ring widths were measured to the nearest 0.001 mm using the Windendro software program. The ARSTAN program was used to standardize the tree-ring data and to calculate dendrochronological statistical parameters. The inter-annual variability of tree-ring width and the radial growth trend were examined. Finally, tree-ring widths to climate relationships were calculated by orthogonal regression in combination with the bootstrap procedure using master residual chronology and monthly precipitation, temperature data and scPDSI drought index, from October of the n-1 year up to November of the n year. Results: The master chronology of valonia oak trees in Western Greece reaches 365 years, with an average ring width of 0.89 mm and with mean sensitivity being 0.21. The variation of the tree-ring widths indicates the influence of climate and human intervention in the past. Tree-ring to climate relationships show that valonia oak growth is positively affected by precipitations in January and March and by drought reduction during June and July. Conclusions: Valonia oak in Western Greece is a species of great interest for dendrochronological and dendroclimatological studies due to the old age of the trees and the species response to climate variation. The climate factors that mostly affect its growth are winter and spring precipitation and summer drought.