Oak Pollen Research Articles

Elevated atmospheric CO2 alters the multi-element stoichiometry of pollen-bearing oak flowers, with possible negative effects on bees

Increasing atmospheric CO2 levels change the elemental composition in plants, altering their nutritional quality and affecting consumers and ecosystems. Ecological stoichiometry provides a framework for investigating how CO2-driven nutrient dilution in pollen affects bees by linking changes in pollen chemical element proportions to the nutritional needs of bees. We investigated the consequences of five years of Free Air CO2 Enrichment (FACE) in a mature oak-dominated temperate forest on the elemental composition of English oak (Quercus robur) pollen. We measured the concentrations and proportions of 12 elements (C, N, P, S, K, Na, Ca, Mg, Cu, Zn, Fe, and Mn) in Q. robur pollen-bearing flowers collected from the Birmingham Institute for Forest Research (BIFoR) FACE facility. An elevated CO2 (eCO2) level of 150 ppm above ambient significantly reduced the S, K, and Fe levels and altered the multi-element ratio, with different elements behaving differently. This shift in pollen multi-element composition may have subsequent cascading effects on higher trophic levels. To assess the impact on bees, we calculated the stoichiometric mismatch (a measure of the discrepancy between consumer needs and food quality) for two bee species, Osmia bicornis (red mason bee) and Apis mellifera (honey bee), that consume oak pollen in nature. We observed stoichiometric mismatches for P and S, in pollen under eCO2, which could negatively affect bees. We highlight the need for a comprehensive understanding of the changes in pollen multi-element stoichiometry under eCO2, which leads to nutrient limitations under climate change with consequences for bees.

Local spatiotemporal dynamics of particulate matter and oak pollen measured by machine learning aided optical particle counters

Conventional techniques for monitoring pollen currently have significant limitations in terms of labour, cost and the spatiotemporal resolution that can be achieved. Pollen monitoring networks across the world are generally sparse and are not able to fully represent the detailed characteristics of airborne pollen. There are few studies that observe concentrations on a local scale, and even fewer that do so in ecologically rich rural areas and close to emitting sources. Better understanding of these would be relevant to occupational risk assessments for public health, as well as ecology, biodiversity, and climate.We present a study using low-cost optical particle counters (OPCs) and the application of machine learning models to monitor particulate matter and pollen within a mature oak forest in the UK. We characterise the observed oak pollen concentrations, first during an OPC colocation period (6 days) for calibration purposes, then for a period (36 days) when the OPCs were distributed on an observational tower at different heights through the canopy. We assess the efficacy and usefulness of this method and discuss directions for future development, including the requirements for training data.The results show promise, with the derived pollen concentrations following the expected diurnal trends and interactions with meteorological variables. Quercus pollen concentrations appeared greatest when measured at the canopy height of the forest (20–30 m). Quercus pollen concentrations were lowest at the greatest measurement height that is above the canopy (40 m), which is congruent with previous studies of background pollen in urban environments. The attenuation of pollen concentrations as sources are depleted is also observed across the season and at different heights, with some evidence that the pollen concentrations persist later at the lowest level beneath the canopy (10 m) where catkins mature latest in the season compared to higher catkins.

Safety evaluation of the food enzyme glutaminase from the genetically modified Bacillus licheniformis strain NZYM-JQ.

The food enzyme glutaminase (l-glutamine amidohydrolase EC 3.5.1.2) is produced with the genetically modified Bacillus licheniformis strain NZYM-JQ by Novozymes A/S. The genetic modifications do not give rise to safety concerns. The production strain met the requirements for the qualified presumption of safety (QPS). The food enzyme is free from viable cells of the production organism and its DNA. The enzyme under assessment is intended to be used in six food manufacturing processes. Dietary exposure was estimated to be up to 0.148 mg TOS/kg body weight per day in European populations. Given the QPS status of the production strain and the absence of concern resulting from the food enzyme manufacturing process, toxicological studies were not considered necessary. A search was made for the similarity of the amino acid sequence to those of known allergens and one match with a pollen allergen was found. The Panel considered that the risk of allergic reactions by dietary exposure cannot be excluded, particularly for individuals sensitised to birch and oak pollen. The Panel concluded that the food enzyme does not give rise to safety concerns under the intended conditions of use.

T cells specific to multiple Bet v 1 peptides are highly cross-reactive toward the corresponding peptides from the homologous group of tree pollens.

Allergens from Fagales trees frequently cause spring allergy in Europe, North America, and some parts of Asia. The definition of the birch homologous group, which includes birch (Bet v), oak (Que a), alder (Aln g), hazel (Cor a), hornbeam (Car b), beech (Fag s), and chestnut (Cas s), is based on high allergen sequence identity and extensive IgE cross-reactivity. Clinical effect was seen during the alder/hazel, birch, and oak pollen seasons after treatment with tree SLIT-tablets containing only birch allergen extract. Here, we characterize T-cell reactivity with respect to epitope specificities and cross-reactivity toward various Bet v 1 family members, (PR-10/group 1 major allergens). This cross-reactivity may be part of the immunological basis of clinical effect or cross-protection when exposed to birch homologous tree species. T-cell lines were generated from 29 birch-allergic individuals through stimulation of peripheral blood mononuclear cells (PBMCs) with birch/Bet v or oak/Que a allergen extracts. T-cell responses to allergen extracts, purified group 1 allergens, and overlapping 20-mer peptides (Bet v 1, Aln g 1, Cor a 1, and Que a 1) were investigated by T-cell proliferation and cytokine production. Cross-reactivity was evaluated based on Pearson's correlations of response strength and further investigated by flow cytometry using tetramer staining for homologous peptide pairs. T-cell reactivity toward extracts and group 1 allergens from across the birch homologous group was observed for birch/Bet v as well as oak/Que a T-cell lines. T-cell lines responded to multiple Bet v 1 homologous peptides from Aln g 1 and Cor a 1 and a subset of Que a 1 peptides. Significant Pearson's correlations between frequently recognized peptides derived from Bet v 1 and the corresponding peptides derived from alder, hazel, and oak strongly supported the T-cell cross-reactivity toward these allergens. Cross-reactivity between birch and birch homologous peptides was confirmed by pMHCII tetramer staining. T cells from birch tree pollen allergic individuals respond to multiple trees within the birch homologous group in accordance with the level of sequence homology between Bet v 1 family members, (PR-10 allergens) from these allergen sources, confirming the basis for clinical cross-protection.

Pollen variability in Quercus L. species and relative systematic implications

This study aims to address one of the challenges related to the complexity of the Quercus L. genus, that is the identification of structural elements favouring the systematic identification of the oak pollen. Thus, in this contribution, we explored the variation of morphometric and chemical parameters in pollen samples collected from 47 different Quercus species and hybrids. Several qualitative (e.g., outline in polar view, class, aperture structures) and quantitative (e.g., diameter, exine and sporoderm thickness, autofluorescence, content in proteins and plant metabolites) features were evaluated by optic microscopy and spectrophotometric assays. Statistical analyses were also carried out to assess significant correlations and clustering effects among the studied taxa, based on phenotypical and biochemical data, to identify the parameters which could be useful for taxonomic discrimination at inter- and intra-specific level. Only few morphological traits showed the potentiality to be diagnostic, such as pollen diameter and outline in polar view. The intensity of pollen autofluorescence varied among the samples but it did not seem to correlate with protein, carotenoid, phenolic and flavonoid content. However, differences in protein and carotenoid levels were detected, suggesting them as possible taxonomic discriminants for oak pollen. Thus, our work represents a step forward in understanding morphology and biochemistry of oak pollen, constitutes an experimental set-up applicable in future systematic studies on other genera, and opens new perspectives for further molecular investigations on Quercus species.

Pollen characteristics used in determination and systematics of Quercus (Fagaceae): new data and verification of previous concepts

Abstract Quercus (oaks) is a large and important genus of woody angiosperms occurring in a wide range of environments and often occupying a dominant position in temperate forests of the Northern Hemisphere or being a minor component in some subtropical and tropical forests. A reliable determination of fossil dispersed oak pollen requires combined light, scanning electron (SEM) and transmission electron microscopy (TEM) studies and relevant comparative data on extant oak species. We provide SEM and TEM data on 22 extant Quercus spp., representing all sections of the genus. The main objectives of our study were to clarify the nature of the so-called geniculus, a characteristic equatorial bulge in the exine of the colpus found in many oak species, and to test previous hypotheses about the structural basic units of the exine in Quercus. Our ontogenetic study and oxidative experiment involving several Quercus spp. and one Trigonobalanus sp. resulted in a more accurate interpretation of the nature of the geniculus and exine elements, their different developmental states and, therefore, their more reliable application in the systematics and evolution of the genus Quercus and Fagaceae in general.

Investigation of Altitudinal and Longitudinal Variations of Pollen Grains of the Oak Species (The Genus Quercus L.) in Duhok Province Iraq

Pollen grains of 3 Iraqian oak (Quercus) species belongmg to section Quercus and section cerris growing naturally in Duhok province Iraq. Three altitudinal zones (500-1000 m, 1000-1500 m, 1500-2000 m) were examined by light microscope (LM) and scanning electron microscope (SEM). The main issue focused on in this study is to determine whether oak pollens have changed dimensionally and structurally according to both different latitudes and longitudes. Based on the averages obtained from seven variables, it has been demonstrated comparative data. The mean value, range (min.-max.), and standard deviation (SD) were calculated for polar axis(P), equatorial diameter (E), polar/equatorial ratio (P/E), apocolpium (AP), mesocolpiuin (ME), colpus length (CL) and exine (wall) thickness (ET). Mean values were assessed by the stattsticnl tests to compare the mean values for each variable. Pollen grains of all species are in monad, isopolar, radially symmetrical, their apertures are mostly tricolpate. Rarely 4-colporate as in Q.brantii and Q.libant, Overall mean polar length of Q.brantii, Q.infectoria subsp. Veneri and Q.libani were 24.34, 24.29, and 27.92 µm respectively. Pollen shape classes range from probate-spheroidal to sub-prolate at varying proportions for the species; Quercus brantii (P/E; 1.07 µm), Quercus infectoria (P/E;1.06 µm) and Quercus libani (P/E; 1.14 µm) According to pollen size classes, pollen grains of Q. brantii and Q. infectoria were 67% minute and 33% mediate, while in Q.libani are 100% mediate. Exine sculpturing pattern is gemmate-verrucate for all taxa

Live oak pollen as a source of atmospheric particles

Live oak pollen as a source of atmospheric particles

Oak Pollen Allergy in Korea.

Oak pollen allergy is common all over the world and an important cause of pollinosis. The molecular properties of some component allergens have been clearly characterized, while some of them are still waiting for characterization. Studies on some oak component allergens are neglected, possibly because of its high cross-reactivity to birch. However, the utilization of culprit allergen molecules is expected to increase the diagnostic sensitivity and efficacy of immunotherapy. Sensitization to oak pollen along with birch often causes pollen food allergy syndrome to fruits and vegetables. Acorn and wood dust from oak can cause allergic disease. We summarize the distribution and taxonomic classification of oak trees of allergenic importance. Molecular characteristics of the identified component allergens, cross-reactivity, and clinical aspects for diagnosis and immunotherapy are also described with an emphasis on Korean situations.

Modeling past and future spatiotemporal distributions of airborne allergenic pollen across the contiguous United States.

Exposures to airborne allergenic pollen have been increasing under the influence of changing climate. A modeling system incorporating pollen emissions and atmospheric transport and fate processes has been developed and applied to simulate spatiotemporal distributions of two major aeroallergens, oak and ragweed pollens, across the contiguous United States (CONUS) for both historical (year 2004) and future (year 2047) conditions. The transport and fate of pollen presented here is simulated using our adapted version of the Community Multiscale Air Quality (CMAQ) model. Model performance was evaluated using observed pollen counts at monitor stations across the CONUS for 2004. Our analysis shows that there is encouraging consistency between observed seasonal mean concentrations and corresponding simulated seasonal mean concentrations (oak: Pearson = 0.35, ragweed: Pearson = 0.40), and that the model was able to capture the statistical patterns of observed pollen concentration distributions in 2004 for most of the pollen monitoring stations. Simulation of pollen levels for a future year (2047) considered conditions corresponding to the RCP8.5 scenario. Modeling results show substantial regional variability both in the magnitude and directionality of changes in pollen metrics. Ragweed pollen season is estimated to start earlier and last longer for all nine climate regions of the CONUS, with increasing average pollen concentrations in most regions. The timing and magnitude of oak pollen season vary across the nine climate regions, with the largest increases in pollen concentrations expected in the Northeast region.

Oak pollen season in selected cities in Poland in 2022

Oak (Quercus sp.) is a common species in Poland. Que a 1, which triggers allergic reactions in spring, is the main oak allergen. The aim of the study was to compare the oak pollen season in 13 Polish cities in 2022. Pollen was monitored with the volumetric method. The analyses determined the annual sum of pollen grains, the length of the pollen season (using the 98% method), the highest peak pollen concentrations, the dates of maximum pollen concentrations, and the number of days with pollen concentrations above threshold values causing clinical allergy symptoms. The earliest onset of the oak pollen season was noted in Szczecin (April 11th), and the latest beginning was recorded in Lublin and Kielce (May 5th). The shortest and the longest pollen seasons were recorded in Cracow (22 days) and in Szczecin (48 days), respectively. The highest total daily concentration of pollen grains was recorded in Opole (5083) and the lowest value was noted in Bialystok (112) and Szczecin (328). The highest maximum concentration of oak pollen was recorded in Sosnowiec and Kielce (625 and 543 grains/m3, respectively), whereas the lowest values were noted in Bialystok and Szczecin (27 and 47 grains/m3, respectively). In most of the analyzed cities in Poland, the peak oak pollen release was recorded between May 7th and 12th. The highest risk of allergic reactions caused by oak pollen allergens was reported from Opole, Piotrkow Trybunalski, and Zielona Gora.

Differential Bacterial Community of Bee Bread and Bee Pollen Revealed by 16s rRNA High-Throughput Sequencing.

Simple SummaryGut symbionts play a crucial role in the nutrition provisioning of honeybees. However, the data on the bacterial communities of pollen collected by bees and bee bread are comparatively scarce. Therefore, the present study was designed to explore and identify the bacterial communities from them. The study reports that the bacterial diversity was significantly higher in the bee bread than in bee pollen. The higher bacterial diversity in the bee bread could presumably be due to factors such as storage period, processing of food, fermentation, and high sugar environment. The bacterial communities of bee bread possibly exhibit beneficial roles for honeybees such as polysaccharide degradation and nitrogen fixing.We investigated the bacterial community of bee bread and bee pollen samples using an approach through 16 s rRNA high-throughput sequencing. The results revealed a higher bacterial diversity in bee bread than in bee pollen as depicted in taxonomic profiling, as well as diversity indices such as the Shannon diversity index (3.7 to 4.8 for bee bread and 1.1 to 1.7 for bee pollen samples) and Simpson’s index (>0.9 for bee bread and 0.4–0.5 for bee pollen). Principal component analysis showed a distinct difference in bacterial communities. The higher bacterial diversity in the bee bread than bee pollen could presumably be due to factors such as storage period, processing of food, fermentation, and high sugar environment. However, no effect of the feed (rapeseed or oak pollen patties or even natural inflow) was indicated on the bacterial composition of bee bread, presumably because of the lack of restriction of foraged pollen inflow in the hive. The diverse bacterial profile of the bee bread could contribute to the nutritional provisioning as well as enhance the detoxification process; however, a thorough investigation of the functional role of individual bacteria genera remains a task for future studies.

Holocene upland and wetland dynamics in the Chihuahuan Desert, Cuatrociénegas Mexico

The Cuatrociénegas Basin, Coahuila MX, has the highest rate of endemism in North America and has been the source of a rich aridlands, paleoenvironmental history in the Chihuahuan Desert of North America. Understanding the recent past of the Cuatrociénegas Basin contextualizes how aridland terrestrial and wetland systems may respond to ongoing climate warming and the potential aridification in already water-limited regions. A 12.3 m long sediment core dated to ~13,500 cal yr BP was collected from Poza Cortador and examined for pollen to reconstruct the Holocene terrestrial and wetland history of the Basin. The terrestrial record indicates a transition from woodland to desert environments by ~7500 cal yr BP. This transition is characterized more by the decrease in conifer and oak pollen abundances relative to desert taxa rather than a sudden appearance of new pollen types. Wetlands appear more stable than the terrestrial record, possibly because of groundwater buffering of the wetland surface. Alternatively, there might be less obvious changes because of the overall pollen diversity of identified wetland pollen types selected in this study. Significant aridity in both the terrestrial and wetland environments is inferred between 5000 and 3000 cal yr BP based on poor pollen preservation. The record of the last 3000 cal yrs reflects the resilience of both the terrestrial and wetland systems to prolonged drought and provides hope that this unique system may have resiliency to some aspects of future climate change if the hydrologic connectivity can remain intact.

Oak and hornbeam pollen season in Kielce in 2021

The paper presents the characteristics of oak and hornbeam pollen seasons in Kielce in 2021. Aeropalinological measurements were carried out with the use of the volumetric method. The main oak pollen season lasted 35 days. The maximum concentration of oak pollen, i.e. 227 grains in 1 m3 of air, was recorded on May 20, and the seasonal pollen index was estimated at 1533. The hornbeam pollen season was longer, i.e. 56 days. The peak hornbeam pollen release was recorded on April 28, when 22 pollen grains in 1 m3 of air were noted, with the annual concentration sum of 207. The study also determined the effect of some meteorological factors on the concentration of pollen grains of the analyzed plant taxa. The meteorological parameters were found to exert the strongest effect on the dynamics of the hornbeam pollen season.

Sensitization profile to sawtooth oak component allergens and their clinical implications

ObjectiveThe component allergens from sawtooth oak, which is a main cause of tree pollinosis in Korea, have not been extensively characterized except Que ac 1. This study was undertaken to characterize the allergenic components from sawtooth oak pollen and investigate the diagnostic values of each component allergen.MethodsTranscriptomic analysis was performed to identify the birch pollen allergen homologues from sawtooth oak pollen. Recombinant Que ac 1, 2, 3, 6, 7, and 8 were produced in an E. coli expression system. IgE reactivity to each allergen was examined by ImmunoCAP and ELISA using the sera of 50 Korean tree pollinosis patients.ResultsSix birch pollen allergen homologues were identified using transcriptome analysis, as follows: Que ac 1 (54.8% identity to Bet v 1), Que ac 2 (79.7% to Bet v 2), Que ac 3 (24.9% to Bet v 3), 6 (71.3% to Bet v 6), Que ac 7 (80.9% to Bet v 7), and Que ac 8 (78.9% to Bet v 8). Que ac 1 sIgE was the most frequently recognized (84.0%), followed by Que ac 2 (12.0%), Que ac 3 (6.0%), and three other allergens (2.0% each). Que ac 1 was a dominant allergen affecting 83.7% of patients suffering from allergic rhinoconjunctivitis, and 92.9% of pollen food allergy syndrome patients.ConclusionFive novel IgE reactive components of sawtooth oak were characterized using transcriptome analysis. Que ac 1 is the single most important component allergen of sawtooth oak pollen.

How does feeding on different diets affect the life history traits of Neoseiulus californicus?

ABSTRACT We examined how feeding on different diets affects the life-history traits of Neoseiulus californicus using seven pollen grains (pistachio, walnut, date palm, wild almond, pomegranate, oak, and peach) as well as a natural prey (two-spotted spider mites (TSSM)). The pre-adult duration of individuals reared on TSSM was significantly longer, whereas duration on oak and peach pollen was shorter than all the others. Females fed on peach, wild almond, and walnut pollen showed low fecundity. The highest number of eggs was laid by the females reared on TSSM. When the mites were reared on pistachio pollen, the fecundity was higher compared with other pollen grains. The net reproductive rate (R 0) varied from 1.77 (on peach pollen) to 26.28 offspring (on TSSM). The cohort reared on pistachio pollen had the highest intrinsic rate of increase (r) as well as the finite rate of increase (λ); however they were insignificant to the values obtained for the cohort reared on the date palm, oak, and pomegranate pollen. Pistachio and date palm pollen provide commensurate nutritional effects on survivorship, development, and fecundity of N. californicus. Knowledge about the profitability of different pollens can be used to optimize rearing systems for phytoseiid predators.

Treatment Effect of the Tree Pollen SLIT-Tablet on Allergic Rhinoconjunctivitis During Oak Pollen Season

Birch, alder, hazel, and oak are members of the birch homologous group based on cross-reactivity toward the birch pollen allergen Betula verrucosa 1. Theoretically, allergy to these tree pollens may be treated by immunotherapy with one representative allergen extract. To evaluate post hoc whether treatment of birch pollen-induced allergic rhinoconjunctivitis with a standardized tree sublingual immunotherapy (SLIT)-tablet containing birch pollen extract reduces symptoms and symptom-relieving medication use during the oak pollen season (OPS). In a randomized, multinational, double-blind trial (EudraCT-2015-004821-15), 634 participants (ages 12-65 years) received daily tree SLIT-tablet (12 SQ-Bet) or placebo before and during tree pollen season (alder/hazel plus birch pollen season [BPS]). Symptom-relieving medication was allowed. The primary end point was the average total combined score (sum of rhinoconjunctivitis daily symptom score and daily medication score) during BPS. Outcomes during the OPS (excluding overlapping BPS days) were analyzed post hoc. Relative improvements in average total combined score, daily symptom score, and daily medication score with the tree SLIT-tablet versus placebo during the OPS were 25%, 22%, and 32%, respectively (all P < .001). Significant correlations were observed between birch and oak serum immunoglobulin E (sIgE) at baseline (r= 0.86) and between birch and oak IgG4 after treatment (r= 0.72). Oak sIgE and IgG4 kinetics in response to tree SLIT-tablet treatment were similar to birch. The tree SLIT-tablet leads to significant improvement of rhinoconjunctivitis outcomes during the OPS, supporting the clinical relevance of immunological cross-reactivity toward birch and oak allergens.

Allergy to oak pollen in North America

Background: Oak pollen is an important allergen in North America. The genus Quercus (oak) belongs to the family Fagaceae under the order Fagales. Objective: The objective of this article was to narratively review the oak pollen season, clinical and epidemiologic aspects of allergy to oak pollen, oak taxonomy, and oak allergen cross-reactivity, with a focus on the North American perspective. Methods: A PubMed literature review (no limits) was conducted. Publications related to oak pollen, oak-related allergic rhinitis with or without conjunctivitis, and oak-related allergic asthma were selected for review. Results: Oak species are common throughout the United States and contribute up to 50% to overall atmospheric pollen loads. Mean peak oak pollen counts can reach >2000 grains/m³. The start of the oak pollen season generally corresponds to the seasonal shift from winter to spring based on latitude and elevation, and may begin as early as mid February. The duration of the season can last > 100 days and, in general, is longer at lower latitudes. In the United States, ∼30% of individuals with allergy are sensitized to oak. The oak pollen season correlates with increased allergic rhinitis symptom-relieving medication use and asthma-related emergency department visits or hospitalizations. Oak falls within the birch homologous group. Extensive immunologic cross-reactivity has been demonstrated between oak pollen and birch pollen allergens, and, more specifically, their major allergens Que a 1 and Bet v 1. The cross-reactivity between oak and birch has implications for allergy immunotherapy (AIT) because guidelines suggest selecting one representative allergen within a homologous group for AIT, a principle that would apply to oak. Conclusion: Allergy to oak pollen is common in North America and has a substantial clinical impact. Oak pollen allergens are cross-reactive with birch pollen allergens, which may have implications for AIT.

Oak pollen concentration in the air of selected Polish cities in 2020

The study aims to compare the oak pollen season in selected Polish cities: Bialystok, Bydgoszcz, Cracow, Katowice, Piotrkow Trybunalski, Lublin, Olsztyn, Opole, Szczecin, Warsaw, and Wroclaw in 2020. Measurements were made using the volumetric method, with a Hirst-type sampler. Oak pollen season, defined as the period with 98% of the annual total catch, started between April 14th (in Opole) and April 25th (in Lublin). The season ended on June 1st at the latest; in Sosnowiec, Bydgoszcz, Olsztyn, and Bialystok. It lasted from 30 to 47 days (37 days on average). The maximum daily oak pollen concentrations were observed between April 24th and May 11th. The highest annual sum of oak pollen grains (SPI) was recorded in Lublin, while the lowest in Bialystok. The highest concentrations of 596 oak pollen grains/m3 were noted in Lublin on April 28th. The longest exposure to high concentrations of oak pollen (&gt; 91 grains/m3), lasting 12–13 days, was recorded in Lublin, Opole, and Wroclaw.

Did forest fires maintain mixed oak forests in southern Scandinavia? A dendrochronological speculation

In northern Europe, a long history of human exploitation effectively eliminated legacies of natural disturbances in mixed oak forests and we currently lack understanding of the role of natural disturbance factors in affecting oak regeneration into the forest canopies. We compiled dendrochronological, observational and paleochronological data from Southern Sweden to discuss the role of forest fires in oak (Quercus spp.) dynamics. We analyzed oak age structure and its growth dynamics in six southern Swedish forests, which experienced fires between 42 and 158 years prior to our sampling. Extending our analysis over longer time frames, we studied the relationship between sediment charcoal and oak pollen in an area of south-eastern Sweden, where oak has been a common canopy species. In three of the study sites, forest fires resulted in increased oak regeneration. Although fires were generally not associated with a wave of growth releases in surviving trees, the mean basal area growth rate of oaks increased by a range of 108% to 176%, following the fires. The overall pattern indicated that historical fires in oak-dominated forests were of low severity, did not kill canopy oaks, and yet provided a window of regeneration opportunities for that species. Post-fire sprouting of oak and an increase in oak seedling densities following modern prescribed fires are consistent with this explanation. Consistent with this conclusion were significant positive correlations between charcoal concentration and the oak pollen percentage in a site in southeastern Sweden. We discuss the co-occurrence of oak and pine in the historical southern Swedish landscape, as a possible analogy to eastern North American oak-pine forests. Modern conservation policies aimed at the preservation of oak in the southern Swedish landscape should consider the use of low severity fires to maintain natural oak regeneration.