Tree-ring Width Research Articles

Interrelationship between tree-ring width and supra-annual reproductive behaviour of Cedrela odorata: an alert for dendrochronological research

Abstract Allocating resources for reproduction involves ecological and evolutionary factors and can reduce vegetative growth in plants. This interrelationship is not easily observed in nature, as there are many parameters that can limit the production of reproductive structures or the addition of biomass. We related tree-ring width to supra-annual reproductive behaviour of Cedrela odorata L. (Meliaceae) in the Atlantic Forest of Rio de Janeiro State. In general, the development of reproductive structures occurred in wet years, without water deficit at the beginning of the growth season. However, in these years, tree-ring width was smaller. These results may be associated with the lack of correlation between tree-ring width and local climate. In this way, we highlight the importance of incorporating reproductive data in radial growth studies to expand the understanding of growth variability in tropical forests.

Reconstruction of Seasonal Kinetics in Conifer Radial Growth from Daily Meteorological Conditions, Tree-Ring Width, and Radial Size of Tracheids

The development of the tree ring is a process occurring under limitations caused by a complex of environmental factors and intrinsic regulatory mechanisms. Its understanding is of interest in many scientific fields, but most quantitative models trying to describe its details meet several issues stemming from the difficulty of its verification. This study attempted to combine several observational and modeling approaches to verify intermediate details of the description of xylogenesis, aiming to restore the tree-ring seasonal growth kinetics on the basis of dendrochronological and wood anatomical data. It was carried out for Scots pine in two semiarid habitats in South Siberia. The Vaganov-Shashkin model was used jointly with tree-ring width chronology and climatic data to model the tree radial growth rate with daily precision. The Band-model was then used to calculate the kinetics of tracheid production from the growth rate and actual final number of cells per radial file in the ring. Seasonal observations of cell population and final measurements of cell sizes were used to fit model parameters and verify the numbers of developing tracheids produced by the Band-model. The patterns of modeled seasonal kinetics for six seasons and two sites were found to repeat the actual drought-derived deviations in tree growth and observations (R2 = 0.70–0.84). Further research is required to test other climatic limitations and species-specific ecophysiological mechanisms of growth regulation.

Aging Mongolian pine plantations face high risks of drought-induced growth decline: evidence from both individual tree and forest stand measurements

Discerning vulnerability differences among different aged trees to drought-driven growth decline or to mortality is critical to implement age-specific countermeasures for forest management in water-limited areas. An important species for afforestation in dry environments of northern China, Mongolian pine (Pinus sylvestris var. mongolica Litv.) has recently exhibited growth decline and dieback on many sites, particularly pronounced in old-growth plantations. However, changes in response to drought stress by this species with age as well as the underlying mechanisms are poorly understood. In this study, tree-ring data and remotely sensed vegetation data were combined to investigate variations in growth at individual tree and stand scales for young (9 − 13 years) and aging (35 − 52 years) plantations of Mongolian pine in a water-limited area of northern China. A recent decline in tree-ring width in the older plantation also had lower values in satellited-derived normalized difference vegetation indices and normalized difference water indices relative to the younger plantations. In addition, all measured growth-related metrics were strongly correlated with the self-calibrating Palmer drought severity index during the growing season in the older plantation. Sensitivity of growth to drought of the older plantation might be attributed to more severe hydraulic limitations, as reflected by their lower sapwood- and leaf-specific hydraulic conductivities. Our study presents a comprehensive view on changes of growth with age by integrating multiple methods and provides an explanation from the perspective of plant hydraulics for growth decline with age. The results indicate that old-growth Mongolian pine plantations in water-limited environments may face increased growth declines under the context of climate warming and drying.

Increasing deep soil water uptake during drought does not indicate higher drought resistance

Understanding the water use patterns of different tree species and their adaptability to drought is urgently needed due to global warming. In this study, we investigated the seasonal water uptake patterns of Pinus tabulaeformis and Picea wilsonii on the eastern Tibetan Plateau using stable isotope methods. In addition, tree ring width data was used to evaluate the radial growth resistance of the two species to drought in 2022. The focus was on identifying species differences in water uptake patterns during drought spells and radial growth resistance to drought. The results showed that although Pinus tabulaeformis could increase water uptake from deeper soil layers during drought spells, the radial growth resistance to drought was significantly lower (p < 0.001) than that of Picea wilsonii due to the limited water content in the deep soil layers. In contrast, Picea wilsonii had higher resistance and adaptations to drought based on rapid access to water resources from seasonal precipitation with denser fine roots. Overall, shifting water sources to deeper soils during drought spells was not always effective in alleviating drought stress, but the root structure and deep soil water availability were the key factors influencing the drought resistance of trees. The findings had significant implications for decision-making on the species suitability of plantation projects under future climatic change.

Soil water storage capacity and soil nutrients drive tree ring growth of six European tree species across a steep environmental gradient

Tree growth depends on tree-intrinsic attributes, synecological interactions, atmospheric conditions and soil properties. While the influence of tree factors and climate are analysed in detail in many studies, the effect of soil properties is less investigated and compensatory soil effects are often not quantified. In this study, we use a comprehensive dataset of 1659 tree increment cores from six common Central European tree species (Abies alba, Fagus sylvatica, Larix decidua, Picea abies, Pinus sylvestris, Quercus spp.) sampled at 1562 locations across large environmental gradients in the Eastern Alps. Soil data was available from an extensive soil survey including soil pits, laboratory analysis and the application of pedotransfer-functions. Up to three main tree species per site were sampled and the tree ring widths were dendrochronologically measured and synchronized. Topographic information from a high-resolution Digital Terrain Model, high-resolution climate data and biometric measures were available at each site. To determine the influence of soil water storage capacity and soil nutrient status, we used generalized additive models to expand standard models of well-known drivers of tree growth, including age, climatic water balance and temperature. For the time span of 38 years from 1981 until 2018, we found species-specific impacts of soil properties on tree ring growth. Specifically, soil water storage acted as a buffer to overcome drought periods, in particular for deep rooting tree species like Quercus spp. and Abies alba. In addition, we found species-specific growth reactions to soil nutrient status for nutrient-demanding species likes Fagus sylvatica but no effects for less demanding tree species like Pinus sylvestris. Our results show the magnitude of the effects of soil properties in relation to other growth factors on radial growth of six Central European tree species. Therefore, we posit that, while age and climate do have a stronger influence on tree growth, it is important to consider soil as a growth factor, particularly at the distribution margins along climatic gradients.

The palaeoclimatic potential of recent oak tree-ring width chronologies from Southwest Ukraine

Better insights into spatio-temporal climate signals are needed to understand more clearly the applicability to palaeoclimatic analysis and dendrochronological dating of the long tree-ring oak chronologies currently being compiled in Eastern Europe. This study investigates the climate sensitivity of two recent oak tree-ring width (TRW) chronologies from Transcarpathian and Ciscarpathian Ukraine and their coherence with 35 oak chronologies from Ukraine, Poland, Slovakia, Romania, and Hungary. The new Transcarpathian chronology consists of 247 TRW series of living trees from 13 sites covering the period 1836–2020, while the new Ciscarpathian chronology consists of 215 TRW series from 13 sites and spans the period 1775–2020. Despite the strong similarity between these two chronologies, their responses to climate differ significantly. Growing-season precipitation and particularly drought (three-month SPEI index) were found to be the primary drivers of oak growth on the border between the Carpathians and the northeastern Pannonian Basin. Spatial correlations of the Transcarpathian chronology show particularly high explained variability in the April-August SPEI index, roughly between 18.5–28.5°E and 45–52°N. In the Ciscarpathian, June precipitation primarily influenced oak radial growth but the spatial correlation was quite low. While the Transcarpathian TRW chronology was strongly correlated with eastern Slovakian and northwestern Romanian chronologies, the Ciscarpathian chronology revealed very low correlations with surrounding chronologies. This study indicates the great dendroarchaeological and palaeoclimatic potential of the Transcarpathian chronology and points to the need to analyse additional living trees from the Ciscarpathian region to understand the spatial variability of oak growth and its climate signal better.

Cutting the Greenness Index into 12 Monthly Slices: How Intra-Annual NDVI Dynamics Help Decipher Drought Responses in Mixed Forest Tree Species

We studied the correspondence between historical series of tree-ring width (TRW) and the normalized difference vegetation index (NDVI, i.e., greenness index) values acquired monthly over an entire year by unmanned aerial vehicles. Dendrochronological techniques revealed differentiated responses between species and seasonality. Pinus engelmannii Carrière and Juniperus deppeana Steudel were affected by warm temperatures (TMAX) during the winter prior to growth and benefited from precipitation (PP) during the seasons prior to the spring period. The standardized precipitation–evapotranspiration index (SPEI) confirmed the high sensitivity of P. engelmannii to drought (r = 0.7 SPEI). Quercus grisea Liebm. presented a positive association with PP at the beginning and end of its growth season. Monthly NDVI data at the individual tree level in the three species (NDVI ~0.37–0.48) statistically confirmed the temporal differences. Q. grisea showed a drastic decrease during the dry season (NDVI = 0.1) that had no impact on drought sensitivity in the same period, according to the climate-TRW relationship. We conclude that a relationship is plausible between the crown greenness index and radial growth, although more extended temporal windows of the NDVI should be explored. Differences in susceptibility to drought found among the species would presumably have implications for the composition of these forests under drought scenarios.

Chestnut blight (Cryphonectria parasitica (Murr.) Barr) disease incidence and its effect on the morphological and anatomical features of Castanea sativa trees

AbstractSweet chestnut (Castanea sativa) is an ecologically and economically valuable tree species worldwide. Various pathogens, both endemic or introduced, cause severe damage or death to chestnut trees. Chestnut blight, caused by the fungus Cryphonectria parasitica, is one of the most devastating plant diseases known which influences chestnut trees in all major cultivation regions. The work presented here aimed to investigate how the incidence of chestnut blight varied between trees growing at two altitudes (200–400 m vs. 400–600 m) and to determine the impact of chestnut blight on tree‐ring width, morphology and anatomy of C. sativa trees. The incidence of C. parasitica infections was greater at 200–400 m than at 400–600 m. Greater stem diameters were found at 200–400 m than at 400–600 m. There were no differences in stem diameters and heights, however, between healthy and C. parasitica infected chestnut trees. The anatomical characteristics of wood were also compared between healthy and C. parasitica‐infected chestnut trees. Fibre cell traits (length/width, lumen width, lumen area) were higher in healthy trees than in C. parasitica‐diseased trees. Vessel diameters were greater in infected compared with healthy trees. Tree ring widths and wood anatomical characteristics therefore were significantly influenced by C. parasitica infections.

Changing climate yet healthy forest stand of Tsuga dumosa in temperate zone of central Nepal

Nepal Himalaya is experiencing a faster rate of temperature rise than the global average, and the temperature has altered the growth patterns and distribution of mountain trees. A dendrochronological study was conducted for Tsuga dumosa (D.Don) Eichler to analyze growth-climate relationship from the temperate forest of central Nepal. We developed 116 year-long tree ring width chronology spanning from 1905 to 2020 CE. The study area showed a significant increase in atmospheric temperature and a decrease in rainfall during the past 42 years. It is found that the spring season (March–May) climate is sensitive to the radial growth of T. dumosa. Ring width indices showed a substantial positive correlation with the minimum temperature of January, March, and June of the growth year. Conversely, a negative correlation was observed with the maximum temperature of the previous year's months (July, September, and November), March, and September of the current year, and rainfall during June and November. Basal Area Increment (BAI) trend is positive, indicating the forest is healthy despite the decline in the years 1942, 1978, and 1998. We conclude that the warming of the spring season (March–May), previous year's late growing season and moisture supply (precipitation) during June are critical to the radial growth of Tsuga dumosa in the region. However, responses from multiple species and their exposure to different climate regimes would ideally be required to make predictions on the growth climate relationships of forest trees.

Dendroclimatic studies of Larix cajanderi Mayr. in the Omoloy River Basin

This study presents the results of research on the climatic signal of radial growth of Siberian larch (Larix cajanderi Mayr.) in the Omoloy River Basin, (north-eastYakutia). Tree-ring width chronologies were obtained from three sites located in the valley complexes of subarctic tundra and forest-tundra ecotone, with chronologies spanning up to 498 years. Comparative analysis of radial growth dynamics and its statistical parameters indicated similar variability patterns within the study region. Dendroclimatic analysis revealed that the primary limiting factor determining the magnitude of radial growth in Siberianlarch is the air temperature during the first half of the growing season. Increasing temperatures have led to an increased role of precipitation and changes in the strength of growth-temperature correlations, especially in northern sites.This study highlights the potential for dendroclimatic and dendroecological researchin northern Yakutia.

Multi-century (635-year) spring season precipitation reconstruction from northern Pakistan revealed increasing extremes

The Hindu Kush Himalaya region is experiencing rapid climate change with adverse impacts in multiple sectors. To put recent climatic changes into a long-term context, here we reconstructed the region’s climate history using tree-ring width chronologies of climate-sensitive Cedrus deodara and Pinus gerardiana. Growth-climate analysis reveals that the species tree-growth is primarily limited by moisture stress during or preceding the growing season, as indicated by a positive relationship between the chronology and precipitation and scPDSI, and a negative one with temperature. We have reconstructed 635 years (1384–2018 CE) of February–June precipitation using a robust climate reconstruction model that explains about 53% variance of the measured precipitation data. Our reconstruction shows several dry and wet episodes over the reconstruction period along with an increase in extreme precipitation events during recent centuries or years. Long, very wet periods were observed during the following years: 1392–1393, 1430–1433, 1456–1461, 1523–1526, 1685–1690, 1715–1719, 1744–1748, 1763–1767, 1803–1806, 1843–1846, 1850–1855, 1874–1876, 1885–1887, 1907–1909, 1921–1925, 1939–1944, and 1990–1992, while long dry periods were observed during the following years: 1398–1399, 1464–1472, 1480–1484, 1645–1649, 1724–1727, 1782–1786, 1810–1814, 1831–1835, 1879–1881, 1912–1918, 1981–1986, 1998–2003, and 2016–2018 CE. We found predominantly short-term periodicity cycles of 2.0, 2.2, 2.3, 2.4, 2.6–2.7, 2.9, 3.3, 4.8, 8.1–8.3, and 9.4–9.6 years in our reconstruction. Spatial correlation analyses reveal that our reconstruction is an effective representation of the precipitation variability in the westerly climate-dominated areas of Pakistan and adjacent regions. In addition to the influence of regional circulation systems like western disturbances, we found possible teleconnections between the precipitation variability in northern Pakistan and broader-scale climate modes or phases like AMO and ENSO. The study also highlights the prospects of tree-ring application to explore linkages between western disturbance, increasing intensity and frequency of extreme climate events, and analysis of long-term atmospheric circulation over the western Himalayan region.

Water use strategies determine divergent growth trends of spruce and juniper on the southeastern Tibetan plateau

Warming and increased CO2 levels are generally believed to enhance photosynthetic rates (A) and tree growth, especially in alpine treelines. However, this positive effect may be limited by moisture availability. Here we compare the radial growth and intrinsic water use efficiency (iWUE) of two widely-distributed evergreen needleleaf species, Tibetan juniper (Juniperus tibetica) and Balfour spruce (Picea balfouriana), at the same site near the treeline on the southeastern Tibetan Plateau using tree-ring width and dual isotopes (δ13C and δ18O). We observed that with a 70-ppm increase in atmospheric CO2 from 1954 to 2007, juniper radial growth was significantly stimulated, whereas spruce growth remained constant. Correlation analysis between tree-ring width and climate factors revealed that spruce was more moisture-sensitive than juniper. Although the increases in iWUE for juniper (22%) and spruce (26%) were similar, iWUE changes in spruce were more influenced by stomatal conductance (gs) rather than A, supporting that moisture availability inhibits spruce growth. Our study implies that predicting growth dynamics in alpine forests based on the growth-temperature relationship may be inadequate, as they are likely moisture-limited. It also suggests that increases in A may not be as widespread as previously thought, which helps improve forest productivity modeling.

Tree-ring width and stable isotope analyses of Picea sitchensis from Iceland reveal growth potential under predicted climate change

Sitka spruce has been one of the most planted tree species in Iceland since the mid-twentieth century. Here, we use different dendrochronological methods to identify the controlling climatic factors of its growth and possible changes in their influence over time. We develop annually resolved and absolutely dated measurements of tree-ring width (TRW) from 21 trees and oxygen (δ18O) and carbon (δ13C) stable isotopes from six trees to evaluate growth trends and climate sensitivity in Iceland’s Hallormsstaður National Forest over the past 54 years (1965–2018). Warmer and wetter summers in the last few decades have resulted in significantly increasing radial growth. While TRW and δ13C reflect strong July-August temperature signals, with the highest correlation for July, δ18O is mainly controlled by the temperature in March. The occurrence of negative pointer years in TRW decreases with increasing temperature in July but increases with excessive precipitation in August. Our study shows great continued potential for Sitka spruce cultivation in Iceland.

Features of the growth of aspen trees with different levels of development of stem rot (based on the study of the population from the Molokchinsky reserve of the Moscow region)

Populus tremula L. trees from aspen forest stand of “Molokcha botanical and entomological reserve” (Moscow Region) were studied. Trees were categorized into two groups - damaged and not damaged by rot. Average chronologies were constructed for them. Fourier analysis shows the presence of a clearly expressed cyclical component in the variability of the treering width with a period of 9.5 years. The analyzing the influence of climatic factors on radial increment formation in we can state that the most unfavorable impact on wood formation is caused by drought in the beginning of the vegetation period prior to the year of annual ring formation. There is a tendency of being less drought-resistant for diseased trees. The using of Pi-GC/MS method it allowed us to identify specific biochemical features of the wood of trees resistant to aspen tinder: a reduced concentration of polysaccharides and the presence of a synergistic group of lignin.

Influence of crown morphology and branch architecture on tree radial growth of drought-affected Fagus sylvatica L.

Trees are able to adapt to changing environmental conditions through modifications in their crown morphology and branch architecture. In light-limited environments, tree structures are mainly optimised to increase light interception. This might have side effects on other properties such as the hydraulic system that determines water conduction and tree reactions to drought events. Given the increasing exposure of forest ecosystems to drought stress it is thus crucial to investigate possible correlations between the crown morphology and branch architecture and drought responses. Our study aimed to compare different crown archetypes and branch characteristics of European beech (Fagus sylvatica L.) in their reaction to drought, which was assessed by measuring tree-ring widths of increment cores sampled at breast height. Using Terrestrial Laser Scanning and Quantitative Structure Models, we explored various crown morphological and branch architectural characteristics of 67 beech trees and identified three species-specific crown archetypes. The crown archetypes and branch variables were contrasted with growth responses using linear mixed models. While productivity levels differed, the negative impact of drought stress on radial growth was consistent across all crown archetypes. Nevertheless, certain branch architectural variables were important predictors for radial growth in drought situations. Specifically, long water conduction paths and many branching nodes along those paths were positively influencing growth. Our results indicate that trees showing these characteristics might have a competitive edge regarding drought-affected radial growth compared to others. They could be promoted through thinning measures, which would allow improving the adaption of existing beech forests in situ to climate change and drought stress.

Shifting potential for high-resolution climate reconstructions under global warming

Reconstructions of climate in pre-instrumental times are a cornerstone of earth-system science that relies critically on statistical relationships between meteorological observations and natural proxy archives. Recent studies have frequently reported that these relationships are not stable in time (non-stationarity), which might be due to environmental change (climate, atmospheric CO2), data resolution and quality, and statistical methods applied. Here, we assess the elusive impacts of these factors on the palaeoclimatological potential across the Northern Hemisphere. Scrutinizing spatiotemporal patterns in widely applied calibration metrics derived from 3781 tree-ring chronologies and 517 published dendroclimatic studies, we show that temperature and precipitation sensitivity have increased towards present. This increase was most pronounced in moisture-limited areas and accentuated when using daily rather than monthly instrumental data. An assessment of climate scenarios for 2021–2040 indicated further expansion of areas with strong water limitation (+5 ± 2%), whereas the areas with strong temperature limitation are projected to shrink by 8 ± 3% (tree-ring width proxy) and 3 ± 2% (maximum latewood density proxy). These findings indicate that further refinement of statistical methods will likely no longer compensate for trees’ decreasing temperature sensitivity. Further, a scenario of increased CO2 fertilization may mitigate water limitation on tree growth and weaken precipitation reconstructions. Finally, we discuss the potential drivers of non-stationarity and the consequences for high-resolution paleoclimatology.

Incorporating high-resolution climate, remote sensing and topographic data to map annual forest growth in central and eastern Europe

To enhance our understanding of forest carbon sequestration, climate change mitigation and drought impact on forest ecosystems, the availability of high-resolution annual forest growth maps based on tree-ring width (TRW) would provide a significant advancement to the field. Site-specific characteristics, which can be approximated by high-resolution Earth observation by satellites (EOS), emerge as crucial drivers of forest growth, influencing how climate translates into tree growth. EOS provides information on surface reflectance related to forest characteristics and thus can potentially improve the accuracy of forest growth models based on TRW. Through the modelling of TRW using EOS, climate and topography data, we showed that species-specific models can explain up to 52 % of model variance (Quercus petraea), while combining different species results in relatively poor model performance (R2 = 13 %). The integration of EOS into models based solely on climate and elevation data improved the explained variance by 6 % on average. Leveraging these insights, we successfully generated a map of annual TRW for the year 2021. We employed the area of applicability (AOA) approach to delineate the range in which our models are deemed valid. The calculated AOA for the established forest-type models was 73 % of the study region, indicating robust spatial applicability. Notably, unreliable predictions predominantly occurred in the climate margins of our dataset. In conclusion, our large-scale assessment underscores the efficacy of combining climate, EOS and topographic data to develop robust models for mapping annual TRW. This research not only fills a critical void in the current understanding of forest growth dynamics but also highlights the potential of integrated data sources for comprehensive ecosystem assessments.

Climate-growth relationships of Pinus tabuliformis along an altitudinal gradient on Baiyunshan Mountain, Central China

A set of standard chronologies for tree-ring width (TRW), earlywood width (EWW) and latewood width (LWW) in Pinus tabuliformis Carr. along an altitudinal gradient (1450, 1400, and 1350 m a.s.l.) on Baiyunshan Mountain, Central China to analyze the effect of varying temperature and precipitation on growth along the gradient. Correlation analyses showed that at all three altitudes and the TRW and EWW chronologies generally had significant negative correlations with mean and maximum temperatures in the current April and May and with minimum temperatures in the prior July and August, but significant positive correlations with precipitation in the current May. Correlations were generally significantly negative between LWW chronologies and all temperatures in the prior July and August, indicating that the prior summer temperature had a strong lag effect on the growth of P. tabuliformis that increased with altitude. The correlation with the standardized precipitation evapotranspiration index (SPEI) confirmed that wet conditions in the current May promoted growth of TR and EW at all altitudes. Significant altitudinal differences were also found; at 1400 m, there were significant positive correlations between EWW chronologies and SPEI in the current April and significant negative correlations between LWW chronologies and SPEI in the current September, but these correlations were not significant at 1450 m. At 1350 m, there were also significant negative correlations between the TRW and the EWW chronologies and SPEI in the prior October and the current July and between LWW chronology and SPEI in the current August, but these correlations were not significant at 1400 m. Moving correlation results showed a stable response of EWW in relation to the SPEI in the current May at all three altitudes and of LWW to maximum temperature in the prior July–August at 1400 m from 2002 to 2018. The EWW chronology at 1400 m and the LWW chronology at 1450 m were identified as more suitable for climate reconstruction. These results provide a strong scientific basis for forest management decisions and climate reconstructions in Central China.

Influence of drought and minimum temperature on tree growth and water use efficiency of Mediterranean species

The world's forests are currently facing the impacts of climate change and associated extreme events, which are adversely affecting natural ecosystems and increasing risks of forest mortality. In the Mediterranean region, where water is already a limiting factor, drought stress is having a severe impact on tree growth. Different species have developed physiological mechanisms to cope with drought, and an increase in water use efficiency has been observed in several drought-tolerant species. This paper analysed the growth trends and the ecophysiological responses of four widespread Mediterranean species (Pinus pinaster Aiton, Pinus pinea L., Pinus halepensis Mill and Quercus ilex L.) to climate variability, in a natural reserve of the Vesuvio National Park (Southern Italy). Dendrochronological analyses were used to measure tree-ring widths and to estimate basal area increments for each species. Stable isotope analyses of δ13C were performed to calculate intrinsic water use efficiency on an annual scale for the four species. Climate-growth relationships suggested that temperatures, in particular annual minimum temperature, had a significant impact on the growth of each species. The species that showed the highest resistance to hot periods and water scarcity was Pinus halepensis, presenting the highest intrinsic water use efficiency values. On the other hand, Quercus ilex was found to be the most susceptible to prolonged drought periods and sensitive to changes in precipitation, resulting in the weakest growth rates during extreme heat and cold periods. Our study demonstrated the importance of better understanding the ecophysiological responses of each species to develop sound conservation and forest management plans.

Effect of Variable Growth Conditions on Selected Anatomical Properties of Hungarian Turkey Oak Wood

Quercus cerris (Turkey oak) has been categorized as a drought-tolerant species because it can survive with rainfall below 400 mm/year, and it usually develops deep and penetrating taproots. This characteristic suggests that Turkey oak is a survival candidate species for the future environment with the predicted climate scenarios in Hungary. Potentially, Turkey oak could support a sustainable supply of timber to the Hungarian wood industry in the future, as the aesthetic value is similar to that of noble oaks. The objectives of the study are to determine 1; the selected micro-level wood properties (wood tissue characteristics) and 2; the selected macrolevel wood properties (tree-ring width, sapwood-heartwood ratio) for Turkey oak from two different sites. The heartwood portion for all trees constituted 67-82% of the cross-diameter. The growth-ring width decreased from pith to bark. The annual rings in the sapwood had a width value range of 1000 to 1600 μm; in heartwood 1600 to 2500 μm; in juvenile wood 2400 to 3300 μm. Soil quality and stand composition had a significant effect on growth-ring width. Fibre length ranged from 800.03 to 1305.59 m, whereas fibre-wall thickness varied between 11.73 and 18.51 μm, with soil quality and species composition having a highly significant influence. The earlywood parts of the growth rings had a vessel diameter range of 274.62-401.54 μm, whereas the latewood portion ranged from 46.50 to 190.08 μm. Overall, stand composition was a major source of variation in the properties studied.