The vulnerability of floodplain forests, a critically sensitive global ecosystem, is exacerbated by both hydrological management practices and the escalating frequency and severity of drought events ...caused by climate change. This issue is particularly acute in Central European floodplain forests, where river regulation and reduced groundwater levels have markedly contributed to increased water deficits and intensified drought conditions, causing forest growth decline, species dieback and shifts in forest composition. In this study, we utilized tree-ring measurements from pedunculate oak (Quercus robur L.) and narrow-leaved ash (Fraxinus angustifolia Vahl.) across four sites with varying groundwater levels. This approach allowed us to assess the impact of artificial groundwater modifications and drought conditions in their growth, providing valuable insights into the resilience and adaptation of these species. Our study indicates that the most determining drivers of tree-growth are hydrological parameters such as groundwater levels and drought indices while temperature alone was less important for tree growth. However, we observed species-specific growth responses to these environmental drivers. In particular, Q. robur exhibited a greater adaptability to climatic variables, with a weaker relationship of tree-ring width to climate compared to F. angustifolia, which demonstrated a stronger dependence on hydroclimatic variables and appeared to feature a higher drought susceptibility. Our findings also reveal that radial growth during the vegetation period relies on different water sources; in spring, growth is primarily driven by precipitation, while groundwater levels become more critical in summer and autumn. Overall, our study underscores the significant threat posed to floodplain forests by both groundwater modifications and the escalating frequency of drought events. However, not all floodplain species are equally adaptable to these environmental changes, exhibiting varied responses and vulnerability.
•Ring-widths of ring-porous oak and ash were analysed in floodplain forest.•Four sites with comparable climate but varying groundwater levels were evaluated.•Dependence on spring rainfall and groundwater increased over time for both species.•Ash's growth dependence on hydroclimatic factors was more consistent and pronounced.•Oak demonstrated higher drought resilience in its growth patterns.
•We analyzed the genetic diversity and genetic differentiation among 20 populations.•The current gene pool of Q. robur populations in the Southern Urals remains stable.•The historically short period ...of these processes might be reason for this phenomenon.
Development of agriculture in the forest and forest-steppe zones of the vast East European plain over the past millennium has resulted to a significant decrease of broad-leaved forests habitat. It is expected that the disintegration of the forest tree species distribution ranges will lead to the erosion of the population genetic diversity of due to limited gene flow, impacts on gene pools of genetic drift and inbreeding. To investigate this threat, we analyzed the genetic diversity and differentiation among 20 populations of pedunculate oak (Quercus robur L.) from the Ural Mountains (Russia) and neighboring lowlands and foothills. A set of 412 nuclear SNPs loci was used for our study. A positive correlation (r = 0.168, p < 0.05) was observed between genetic and geographical distances. The most genetic variation was distributed within populations (fixation index FST = 0.054). It was found that the values of genetic diversity are similar in large continuous mountain stands (effective number of alleles ne = 1.340, observed heterozygosity HO = 0.213, expected heterozygosity HE = 0.200), in spatially highly fragmented forests of the Cis-Urals (ne = 1.340, HO = 0.210, HE = 0.200) and geographically isolated marginal habitats with populations of hundreds individuals (ne = 1.338, HO = 0.206, HE = 0.198). Only in populations with few dozen individuals, we revealed a statistically significant decrease in the genetic diversity (ne = 1.312, HO = 0.211, HE = 0.184) and increase of numbers of full sibs and level of kinship (the kinship-coefficient Kin = 0.078–0.128 vs Kin = -0.002–0.035 in other populations). Overall, our study demonstrates that the current gene pool of Q. robur populations in the study area remains stable under conditions of significant forest decline and habitat fragmentation. The historically short period of these processes in the region and the genetically successful gene flow between populations over long distances might be reasons for this phenomenon.
•Survival of oaks depends on plant density, tending and Interspecific competition.•Admixed tree species have a positive effect on the oak quality parameters.•Interspecific competition can replace ...successfully intraspecific oak competition.•Reducing oak plant number at establishment without a loss of oak quality.
Due to a lack of oak seeds and planting material at the north-eastern limit of the distribution range of European oak forests (study area: Republic of Tatarstan, Russia), the high initial plant densities typical of oak stands established in central Europe for the production of valuable timber is not feasible in this region. In Russia, the low numbers of oak trees in planted stands (about 4500 oaks/ha) are complemented by abundant natural regeneration of admixed tree species. In this study, the chronosequence method was used to determine the probability of survival and the quality development of young oaks (10–27 years) in Tatarstan as a factor of initial plant numbers, interspecific competition (lime, maple, hazel), oak age and tending measures. The results provided by LMM and GLMM models revealed that the probability of oak survival rises with increasing initial oak plant density and tending, and declines with increasing competitive pressure of maple. While the competition exerted by all admixed tree species had a negative effect on oak growth parameters, it had a positive effect on important oak quality parameters (e.g., diameter and height of the thickest branches, branch-free bole length). However, a positive impact of high initial plant density on oak quality was reduced by strong interspecific competition. Age had a positive effect on oak quality development, and tending a negative effect.
The findings of this study demonstrate that the competitive pressure of admixed tree species can successfully compensate for the positive effects of oak intraspecific competition on oak quality, and may therefore be exploited by forest managers as a means to reduce the cost of oak establishment by using lower plant numbers without risking any loss of oak quality.
► Dendrochronological investigations of beech and oak along precipitation gradient. ► Growth strongly depends on water availability especially during June and July. ► Sensitivity of tree growth and ...correlations to climate increase along gradient. ► Numbers of pointer years increase, changes more pronounced for beech. ► oak might gain competitive advantages under the projected drier climate.
For north-eastern Germany regional climate models project rising temperatures in combination with decreasing summer and increasing winter precipitation. The resulting overall drier conditions during the growing season will considerably impact forest growth there. We evaluate the consequences of increasing drought on the growth of the two locally most important broadleaf tree species common beech (
Fagus sylvatica L.) and pedunculate oak (
Quercus robur L.). Three mixed forests of beech and oak were sampled along a west-east gradient of declining precipitation. In total we used 257 ring-width samples from 133 trees to build six species and site specific chronologies. Additionally, we modelled the soil water budget for each site. We performed continuous and discontinuous (pointer year) analysis of climate-tree-growth relationships with particular emphasis on inter-annual-variations and their dependence upon climatic factors (temperature, precipitation, soil moisture) and on the stability of the obtained relationships. Results of climate-growth correlations together with pointer year analysis indicate a strong dependency of growth of both species from water availability, especially during early summer (June and July). General correlation pattern between growth and climate are similar for both species, but climate sensitivity of beech is generally higher. We identified drought as the main driver of negative growth depressions in both species. Increasing drought stress along the gradient is expressed in higher correlations to climatic variables, higher sensitivity (variance) of growth, and a higher number of negative pointer years for both species. For beech we also found a significant trend of decreasing average growth rates along the gradient. Growth superiority of beech compared to oak declines with decreasing precipitation. The relationships were generally stable throughout the 20th century. A rise of sensitivity together with a higher frequency of negative pointer years during the last decades suggests that increasing climatic variability together with rising temperatures might be influencing growth of
Fagus at the more humid sites. If we substitute space by time it seems that already small changes in precipitation regime can have considerable impact, especially on the growth of beech. Other, more drought tolerant species like oak might gain competitive advantages under the projected climatic changes.
Carbon transport processes in plants can be followed non-invasively by repeated application of the short-lived positron-emitting radioisotope (11)C, a technique which has rarely been used with trees. ...Recently, positron emission tomography (PET) allowing 3D visualization has been adapted for use with plants. To investigate the effects of stem girdling on the flow of assimilates, leaves on first order branches of two-year-old oak (Quercus robur L.) trees were labeled with (11)C by supplying (11)CO2-gas to a leaf cuvette. Magnetic resonance imaging gave an indication of the plant structure, while PET registered the tracer flow in a stem region downstream from the labeled branches. After repeated pulse labeling, phloem translocation was shown to be sectorial in the stem: leaf orthostichy determined the position of the phloem sieve tubes containing labeled (11)C. The observed pathway remained unchanged for days. Tracer time-series derived from each pulse and analysed with a mechanistic model showed for two adjacent heights in the stem a similar velocity but different loss of recent assimilates. With either complete or partial girdling of bark within the monitored region, transport immediately stopped and then resumed in a new location in the stem cross-section, demonstrating the plasticity of sectoriality. One day after partial girdling, the loss of tracer along the interrupted transport pathway increased, while the velocity was enhanced in a non-girdled sector for several days. These findings suggest that lateral sugar transport was enhanced after wounding by a change in the lateral sugar transport path and the axial transport resumed with the development of new conductive tissue.
•Three thinning treatments of different intensity were applied to Quercus robur mixed plantation.•Tree growth and WUEi were affected by crown asymmetry and competition.•High presence of alder ...influenced tree growth due to resources competitions.•The very high selective thinning resulted to be the most appropriate management practice.•Thinning increased productivity and limited water loss.
Thinning intensity is an important factor affecting forest structure and density and influencing tree growth.
The main objective of the study is to evaluate how the different intensity of thinning can influence, in the short and long term, the productivity and intrinsic water use efficiency (WUEi) of Quercus robur L., a widespread European species. Three thinning types of different intensity were applied in 14-year mixed plantation of Quercus robur L. growing with Alnus glutinosa (L) Gaertn., a N-fixing species, with an initial density of 625 trees/ha. A multidisciplinary approach was applied, coupling the tree-ring analyses with the measurements of stable isotopes of carbon and oxygen.
Findings highlighted how the different conditions of light and competition, determined by the type and intensity of thinning, triggered different responses of Q. robur species in terms of growth and WUEi.
Data suggested that the moderate selective thinning (31% reduction of total biomass) was not able to reduce the high competition for resources among individuals: this condition negatively influenced the trees growth. The presence of the N-fixing species, left after the thinning, was not able to counteract the negative effect of competition.
A negative effect on productivity was recorded with the geometric thinning (62% reduction of total biomass). Indeed, this treatment resulted in an increase of asymmetry of the canopy (0.90 vs 0.83, respectively in pre- and post-thinning period), due to the partial crown competition from one side and with a consequent limitation of the photosynthetic activity of the trees. Finally, the very high selective thinning (75% reduction of total biomass) resulted to be the most appropriate management practice, as it guarantees positive effects both in terms of growth and intrinsic water use efficiency. The post thinning conditions determined high photosynthesis rates, an increase of productivity and a limited water loss.
Оцінено вплив суцільних рубань материнських дубових деревостанів у свіжих сугрудах Житомирського Полісся на динаміку фіторозмаїття живого надґрунтового покриву до і після зімкнення лісових культур. ...Встановлено, що перед проведенням суцільних рубок головного користування (РГК) дубові насадження у віці 130-140 років мали середню повноту близькою 0,60 та густий надґрунтовий покрив із 40-50 видів, проективне покриття якого становило 75-80 %. Після проведення суцільних РГК і створення лісових культур у рослинному покриві відбуваються кардинальні зміни, визначальним екологічним фактором яких є видалення деревостану – едифікаторного ярусу лісу, а також підліску та підросту деревних порід. При цьому, проективне покриття трав'яно-чагарничкового ярусу зменшується до 50-55 %, за практично незмінних показників його видової насиченості (близько 50 видів). Але сам видовий склад цього ярусу істотно змінюється. Зокрема, різко зростає кількість лучних злакових видів, що поодиноко траплялися у материнських фітоценозах, появилася значна кількість рудеральних видів, які є переважно однорічниками чи одно-дворічниками (злинка канадська (Erigeron canadensis L.) – 5-7 %, осот звичайний (Cirsium vulgare (Savi) Ten.), фалакролома однорічна (Phalacroloma annuum (L.) Pers.) та ін.). У дворічних незімкнених культурах загальне проективне покриття трав'яно-чагарничкового ярусу зростає до 65 % теж завдяки рудеральних видам. На трирічних зрубах трав'яно-чагарничковий ярус за проективним покриттям та видовим насиченням схожий як на дворічних. Для нього характерним є збереження певної кількості світлолюбних сільвантів, (їх сумарне проективне покриття не перевищує 6-7 %). У наступні роки, завдяки частковому відновленню підліску, підросту і зростанню впливу лісових культур, зі складу живого надґрунтового покриву поступово випадають світлолюбні рудеральні та лучні види і починається відновлення лісової рослинності. У віці 9-10 років крони лісових культур та природного поновлення практично змикаються (на 80-85 %). При цьому частка дуба звичайного (Quercus robur L.) становить 50 %, сосни звичайної (Pinus sylvestris L.) – 20 %, берези повислої (Betula pendula Roth.) – 15 %. Унаслідок змикання крон молодого деревостану та затінення поверхні ґрунту, проективне покриття трав'яно-чагарничкового ярусу зменшується до 60 %, а його видова насиченість – до 43-х видів, при цьому чітко проявляється динамічне відновлення популяцій типових лісових видів, унаслідок чого флористичний склад живого надґрунтового покриву досліджуваних фітоценозів практично повністю відновлюється.
Наведено основні положення з охорони біорізноманіття в Україні та розвитку лісової сертифікації з цього питання. Виявлено потребу у детальних дослідженнях щодо зміни видового складу рослин у процесі ...природних сукцесій у насадженнях різних деревних порід на лісотипологічній основі. Дослідження проведено у філіях ДП "Ліси України" у Житомирській області. Під час спостережень використано загальноприйняті методики у лісознавстві та геоботаніці. Встановлено, що частка проективного покриття рослин трав'яно-чагарничкового ярусу у перестійних дубових (130-140 років) насадженнях становить 70-80 %, тоді як у середньовікових культурах (50-60 років) – 65-70 %. Найпоширенішими видами, у цих дубових деревостанах є конвалія звичайна (Convallaria majalis L.), анемона дібровна (Anemone nemorosa L.), орляк звичайний (Pteridium aquilinum (L.) Kuhn), зірочник лісовий (Stellaria holostea L.) та осока гірська (Carex montana L.). Усі ці види добре відновлюються у лісових культур дуба звичайного після проведення суцільної рубки. З'ясовано, що у деревостанах обох вікових груп трапляється близько 12 видів рослин, які мають проективне покриття понад 1 %. Також у цих дубняках трапляються рослини, які занесено до Червоної книги України, зокрема лілія лісова (Lilium martagon L.) та любка дволиста (Platanthera bifolia (L.) Rich.). Встановлено, що у 50-60-річних культурах дуба звичайного відновлюється склад трав'яно-чагарничкового ярусу (39-48 видів) до тої кількості, яка була притаманна перестійним насадженням (42-52 видів). Виявлено, що у складі трав'яно-чагарничкового ярусу перестійних насаджень широко представлені види узлісь – 18,9 % та луків – 13,2 %, а у культурах дуба звичайного – лісові види – 69,2 %, лучні – 21,2 % і рудеральні – 9,6 %. Встановлено, що величина показника видової подібності Сьоренсена між рослинними угрупованнями перестійних дубових насаджень і середньовікових культур дуба звичайного достатньо висока – 0,86. Отримані матеріали можна використовувати для розроблення нормативних документів, які регулювали б лісогосподарську та лісозаготівельну діяльність, для зниження її впливу на стан лісових екосистем.
•The delay in in the onset of flowering and acorn production restrict oak tree improvement.•An increased rate of early growth may lead to shortening acorn production.•No genetic clustering was ...observed for precocity in young oak trees.•Rapid growth and early fruiting is potentially a great benefit for oak tree improvement.
The primary objective of this study was to evaluate the growth, genetic predisposition and potential for early fructification of pedunculate oak trees (Quercus robur L.) using two different planting stocks: Root Production Method (RPM®) and Cell Grown (CG). The second objective was to investigate the effect of crown clearance on acorn production. This study was undertaken between 2001 and 2016 at an experimental site at Castlearchdale in Northern Ireland initially comprising of 150 CG and 150 RPM® derived one-year old Q. robur seedlings. Both tree seedling groups were each subdivided into two groups of 75 trees based on height: CG1 (20–50 cm); CG2 (>50 cm); RPM® 1 (<76 cm) and RPM® 2 (>76 cm). Viable acorns were produced by each category of tree in the seventh year after planting: CG1 - 1 tree (1.3%); CG2 - 2 trees (2.7%); RPM®1 - 6 trees (8%) and RPM®2 - 12 trees (16%). The RPM® trees were significantly (p < 0.001) taller, thicker and more likely to show early fructification than CG trees. A weak but very highly significant correlation (r = 0.23, p < 0.001) was established between height at planting and early fructification for RPM® Q. robur trees eight years later. Crown clearance in year 14 after planting had no significant effect on acorn production in the following year within the oak tree population. The genetic analysis shows no obvious genetic groupings within the treatment groups nor genetic predisposition. A similar pattern was found for samples producing acorns versus those not producing acorns.
The potential of RPM® planting stock to enhance home grown seed production in Britain and Ireland is discussed in relation to fructification dynamics of oak trees, and physiological and climatic conditions.
Pedunculate oak is among the most economically important deciduous forest tree species in Europe and is also a host for many important ectomycorrhizal (ECM) fungi. The aim of this study was to ...analyse the ECM fungal community in a mature pedunculate oak stand near Morović, Serbia in spring and autumn. ECM fungi were determined by combining morpho-anatomical characterization of ectomycorrhizas with molecular analysis based on PCR amplification of the internal transcribed spacer region of fungal nuclear ribosomal DNA. The number of ECM fungal taxa and the number of different categories of fine roots were counted, diversity indices were calculated, and ECM fungi were classified into exploration types. Twenty-one ECM fungal taxa were recorded in the studied mature pedunculate oak stand, 19 in spring and 13 in autumn. ECM communities consisted of one dominant taxon and a larger number of rare taxa. Lactarius quietus was the most abundant ECM fungus in both seasons which made association with more than half of ECM root tips. At the stand near Morović, contact exploration type (ET) dominated, short-distance ET was less abundant, while medium-distance fringe ET and long-distance ET were rare in both seasons. The most pronounced difference between seasons is recorded in the number of ECM fungal taxa. The number of ECM fungal taxa and diversity indices recorded in the studied pedunculate oak stand were lower or similar compared to values obtained in stands of oak species across Europe.
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